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2015-09-18T09:10:39Z

Lmo: Lmo uploaded a new version of File:P915249.png

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|description={{en|1=Solid geology of the district.. From: Figure 2 in MERRITT, J W, AUTON, C A, CONNELL, E R, HALL, A M, and PEACOCK, J D. 2003. Cainozoic geology and landscape evolution of north-east Scotland. Memoir of the British Geological Survey, Sheets 66E, 67, 76E, 77, 86E, 87W, 87E, 95, 96W, 96E and 97 (Scotland).}}
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Nether Daugh, Kintore - locality, Cainozoic of north-east Scotland

2015-09-17T09:28:10Z

Lmo:

'''From: Merritt, J W, Auton, C A, Connell, E R, Hall, A M, and Peacock, J D. 2003. [[Cainozoic geology and landscape evolution of north-east Scotland. Memoir of the British Geological Survey, sheets 66E, 67, 76E, 77, 86E, 87W, 87E, 95, 96W, 96E and 97 (Scotland)|Cainozoic geology and landscape evolution of north-east Scotland]]. Memoir of the British Geological Survey, sheets 66E, 67, 76E, 77, 86E, 87W, 87E, 95, 96W, 96E and 97 (Scotland).'''
__FORCETOC__
= Nether Daugh, Kintore =
[[File:P915378.png|thumbnail|Glacial and glaciofluvial features and the distribution of glacigenic deposits on Sheet 76E Inverurie. P915378.]]
Fine-grained sediments, containing the remains of plants and insects, recovered from pits excavated in the floodplain of the River Don, provide an insight into the type of environmental change that affected river catchments in north-east Scotland during the late Holocene. In particular, they suggest that aggradation of fine-grained alluvial sediments, which infill abandoned river channels, may have resulted, at least in part, from soil erosion initiated by deforestation and the development of early agriculture.

[[File:P915324.png|left|thumbnail|Lithostratigraphy at the Nether Daugh site. P915324.]]
The Nether Daugh site (NJ 800 160) lies at the foot of a terrace, adjacent to an abandoned meander cut-off, in the Don valley east of Kintore, on Sheet 76E ([[Media:P915324.png|P915324]], [[Media:P915378.png|P915378]]). This part of the Don valley is infilled by at least 16.2 m of sandy silt, with up to 5 m of laminated micaceous brown and grey sandy silt, passing up into olive-green and olive-brown unlaminated silt. These silts underlie up to 4 m of sand and gravel, which is capped by up to 2 m of fine-grained alluvium and soil (Auton and Crofts, 1986; Aitken, 1991). The silts are interpreted as sediments that were laid down in a lake, ponded at the Mill of Dyce (see Site 18 [[Mill of Dyce - locality, Cainozoic of north-east Scotland|Mill of Dyce]]) and which drained away after 11 550 14C years BP (Auton and Crofts, 1986; Aitken, 1991, 1995). The uppermost parts of the silt sequence may contain organic matter, but its presence has not been confirmed.

BGS Borehole NJ 81 NW3 (Auton and Crofts, 1986) drilled at Nether Daugh proved 0.2 m of ‘peat’ approximately 2 m below the base of the fine-grained floodplain alluvium. Two further boreholes ([[Media:P915324.png|P915324]] boreholes 1 and 2) (NJ 8003 1600 and NJ 8002 1599, respectively), were drilled at the site in December 1986 (information from J Maizels and R Gunson, University of Aberdeen, 1986). Borehole 1 confirmed the presence of an organic interval, comprising 1.1 m of grey, organic mud, overlain by 0.5 m of grey sand with branches and twigs of ''Betula'', and overlain in turn by 1.6 m of grey, organic sand. Subsequently, two pits were dug by mechanical excavator, in February 1988, in order to obtain samples of the organic material for palaeoecological analyses.

The stratigraphy of the two pits and the three boreholes from the site are similar (Aitken, 1991) and is summarised in [[Media:P915324.png|P915324]]. Both pits contained an organic unit at least 10 to 20 cm thick, overlying fine-grained silty sand and overlain by 4.0 to 4.5 m of clay and grey pebbly sands. The organic remains in Pit 1 (NJ 8002 1597) comprised twigs, branches, bark, leaves and seeds in a matrix of grey, silty clay. The upper part of the organic unit in Pit 2 (NJ 8004 1603) contained a higher proportion of organic matter. It comprised woody peat, with thin sand laminations that contained plant macrofossils and insect fragments, again within a grey, silty clay matrix. These organic sediments are interpreted as part of a late Holocene channel fill succession (Aitken, 1991).

{| class="wikitable" style="float:right; margin-left: 10px;"
|+ style="caption-side:top;"|Pollen count from the Nether Daugh Pits
|-
!
! colspan="2"|Percentage total dry land pollen
|-
! ||Pit 1||Pit 2
|-
|''Betula''||15.4||13.2
|- valign="top"
| ''Pinus''||1.1||1.8
|- valign="top"
| ''Quercus''||0.6||0.9
|- valign="top"
| ''Alnus''||14.3||11.0
|-
|- valign="top"
| ''Corylus''/''Myrica''||12.0||11.0
|- valign="top"
| ''Salix''||2.3||1.3
|-
|- valign="top"
| Gramineae||26.3||30.4
|- valign="top"
| Cyperacea||15.6||26.0
|- valign="top"
| Ericales||9.4||6.4
|- valign="top"
| Caryophyllaceae||0.6||1.3
|- valign="top"
| ''Epilobium''||1.1||
|- valign="top"
| Umbelliferae||0.6||
|-
|- valign="top"
| ''Polypodium''||0.6||0.4
|-
|- valign="top"
| ''Sphagnum''||5.2||0.8
|- valign="top"
| ''Filicales''||3.1||3.4
|}

Although only bulk samples of the organic remains were obtained, pollen analysis, and 14C dating of the organic unit was undertaken. Its pollen content was similar in both pits (see table right) and indicated sparse vegetation. Non-arboreal pollen is dominant, particularly Gramineae and Cyperaceae, and to a lesser extent Ericales. However, ''Betula, Alnus ''and ''Corylus/Myrica ''were present in significant proportions. The environment was, therefore, dominated by grass with some heathland, perhaps on the valley sides. Cyperaceae, and possibly ''Myrica'', probably grew in the silted, abandoned channel, while some stands of birch, alder and possibly hazel woodland were present locally (Aitken, 1991).

A single sample from Pit 2 was separated into plant macrofossil and organic fractions for radiocarbon dating. The respective fractions yielded dates of 3855 ± 50 14C years BP (SRR–3718 i) and 4120 ± 50 14C years BP (SRR–3718 ii) (table below). The slight discrepancy between the two ages is attributed to the presence of reworked older organic residues in the silt.

{| class="wikitable"
|+ style="caption-side:top;"|Radiocarbon dates from Late-glacial sites in the district
|-
! Site||Grid reference||Laboratory number||Age (year BP)||Dated material and setting||Reference
|-
| Rothes cutting||NJ 277 498||Beta 8653||11 110 ± 70||peat under remobilised till||Appendix 1
|-
| Garral Hill, Keith||NJ 444 551||Q-104||10 808 ± 230||peat under remobilised till||Godwin and Willis (1959)
|-
| Garral Hill, Keith||NJ 444 551||Q-103||11 098 ± 235||peat under remobilised till||Godwin and Willis (1959)
|-
| Garral Hill, Keith||NJ 444 551||Q-102||11 308 ± 245||peat under remobilised till||Godwin and Willis (1959)
|-
| Garral Hill, Keith||NJ 444 551||Q-101||11 888 ± 225||peat under remobilised till||Godwin and Willis (1959)
|-
| Garral Hill, Keith||NJ 444 551||Q-100||11 358 ± 300||peat under remobilised till||Godwin and Willis (1959)
|-
| Woodhead, Fyvie||NJ 788 384||SRR-1723||10 780 ± 50||peat under remobilised till||Connell and Hall (1987)
|-
| Howe of Byth||NJ 822 571||SRR-4830||11320||peat beneath gravel||Hall et al. (1995)
|-
| Moss-side, Tarves||NJ 833 318||I-6969||12 200 ± 170||peat under remobilised till||Clapperton and Sugden (1977)
|-
| Loch of Park||NO 772 988||HEL-416||10 280 ± 220||kettlehole infill||Vasari and Vasari (1968)
|-
| Loch of Park||||HEL-417||11 900 ± 260||kettlehole infill||Vasari and Vasari (1968)
|-
| Mill of Dyce||NJ 8713 1496||SRR-762||11 550 ± 80||kettlehole infill||Harkness and Wilson (1979)
|-
| Mill of Dyce||NJ 8713 1496||SRR-763||11 640 ± 70||kettlehole infill||Harkness and Wilson (1979)
|-
| Glenbervie||NO 767 801||GX-14723||12 460 ± 130||peat under remobilised till||Appendix 1
|-
| Glenbervie||NO 767 801||SRR-3687a. (humic)||12 305 ± 50||peat under remobilised till||Appendix 1
|-
| Glenbervie||NO 767 801||SRR-368Th (humin)||12 340 ± 50||peat under remobilised till||Appendix 1
|-
| Brinzieshill Farm||NO 7936 7918||SRR-387||12 390 ± 100||peat under remobilised till||Auton et al. (2000)
|-
| Rothens||NJ 688 171||SRR-3803||10 680 ± 100||kettlehole infill||Appendix 1
|-
| Rothens||NJ 688 171||SRR-3804||11 640 ± 160||kettlehole infill||Appendix 1
|-
| Rothens||NJ 688 171||SRR-3805||11 760 ± 140||kettlehole infill||Appendix 1
|}

Palaeoentomology was carried out on a single 3.5 kg sample from Pit 2. The full list of Coleoptera is given in the table below. The limited beetle fauna describes a landscape consistent with that suggested by the pollen evidence. Both suggest that the organic unit developed in an abandoned former channel of the river. The plant debris created a wet, boggy surface with open pools of stagnant or only slowly moving water bordered by reed swamp and a ground layer of hygrophilous herbs and scrubby brush or woodland. There is some indication that this was located within a moorland landscape (Dinnin in Aitken, 1991). Some of the beetle species shed light on the interpretation of the channel fill and subsequent floodplain sedimentation. The leaf beetle ''Chrysolina fastuosa ''feeds on hemp and deadnettle, which are arable and cultivated land species. Furthermore, ''Selatosomus incanus ''(click beetle) and ''Trechus quadristriatus ''(ground beetle) are species of open ground, and are commonly found on arable land (Harde, 1981; Lindroth, 1985). These three species indicate the possibility of arable agriculture (Dinnin in Aitken, 1991).

{| class="wikitable"
|+ style="caption-side:top;"|Coleoptera from Nether Daugh (Pit 2)
|-
! Species||Head||Thorax||Left elytron||Right elytron||No.
|- valign="top"
| CARABIDAE||||||||||
|- valign="top"
| Trethus quadristriatus (Sch.)||||1||1||||1
|- valign="top"
| Bernbidion Maris (Pz.)||1||||||1||1
|- valign="top"
| Pterostithus strenuus (Pz.)||||1||||1||1
|- valign="top"
| Agonum fuliginosum (Pz.)||11||15||9||10||15
|- valign="top"
| Dromius sp.||||||1||||1
|- valign="top"
| DYTISCIDAE||||||||||
|- valign="top"
| Hygrotus sp.||1||||||||1
|- valign="top"
| Hydroporus palustris (L.)||4||3||3||3||4
|- valign="top"
| Hydroporus sp.||||1||||||1
|- valign="top"
| ''Agabus''/''Ilybius'' sp.||F||F||F||F||F
|- valign="top"
| Rhantus/Acilius sp.||||||F||F||F
|- valign="top"
| Colymbetes fustus (L.)||||||1||1||1
|- valign="top"
| HYDROPHILIDAE||||||||||
|- valign="top"
| Helophorus sp.||1||2||1||1||2
|- valign="top"
| Cercyon sp.||1||1||||||1
|- valign="top"
| Hydrobius fustipes (L.)||||||1||||1
|- valign="top"
| Laccobius minutus (L.)||1||1||4||3||4
|- valign="top"
| HYDRAENIDAE||||||||||
|- valign="top"
| Octhebius sp.||||||||1||1
|- valign="top"
| ''Hydraena riparia'' (Kug.)||1||1||1||1||1
|- valign="top"
| ''Limnebius'' sp.||||1||||||1
|- valign="top"
| STAPHYLINIDAE||||||||||
|- valign="top"
| ''Lesteva'' sp.||1||||||||1
|- valign="top"
| Stems comma (LeC.)||||||1||1||1
|- valign="top"
| ''Sterzus'' sp.||10||8||12||10||12
|- valign="top"
| ''Lathrobium ?brunnipes'' (Fab.)||1||2||2||2||2
|- valign="top"
| ''Lathrobium'' sp.||1||||1||1||1
|- valign="top"
| ''Gabrius'' sp.||1||||||||1
|- valign="top"
| ''Quedius'' spp.||||2||||1||2
|- valign="top"
| ''Taehyporus ?solutus'' (Erich.)||||||||1||1
|- valign="top"
| ''Taehinus corticinus'' (Gray.)||1||2||1||4||4
|- valign="top"
| ''T latitollis'' (Gray.)||3||3||4||7||7
|- valign="top"
| Aleocharinae gen. et sp. indet.||49||70||59||52||70
|- valign="top"
| SCARABAEIDAE||||||||||
|- valign="top"
| Aphodius sphacelatus (Pz.)||1||||1||||1
|- valign="top"
| SCIRTIDAE||||||||||
|- valign="top"
| Cyphon spp.||12||12||24||20||24
|- valign="top"
| ELMIDAE||||||||||
|- valign="top"
| Esolus parallelepipedus (Muller)||1||2||2||2||2
|- valign="top"
| ELATERIDAE||||||||||
|- valign="top"
| ''Selatosomus intanus'' (Gyn.)||||1||||1||1
|- valign="top"
| CANTHARIDAE||||||||||
|- valign="top"
| ''Cantharis'' sp.||2||||||1||2
|- valign="top"
| NITIDULIDAE||||||||||
|- valign="top"
| ''Meligethes'' sp.||||||1||||1
|- valign="top"
| CRYPTOPHAGIDAE||||||||||
|- valign="top"
| ''Atomaria Nesomela'' (Herbst.)||||||1||2||2
|- valign="top"
| LATHRIDIIDAE||||||||||
|- valign="top"
| ''Enicmus ?transversus'' (Oliv.)||||1||||||1
|- valign="top"
| CHRYSOMELIDAE||||||||||
|- valign="top"
| ''Donacia'' sp.||||||1||||1
|- valign="top"
| ''Plateumaris sericea'' (L.)||4||1||2||2||4
|- valign="top"
| ''Chrysolina'' ?''fastuosa'' (Scop.)||1||1||1||1||1
|- valign="top"
| ''Phyllotreta'' sp.||||||1||||1
|- valign="top"
| APIONIDAE||||||||||
|- valign="top"
| ''Apion'' sp.||1||2||1||||2
|- valign="top"
| CURCULIONIDAE||||||||||
|- valign="top"
| ''Phyllobius ?roboretanus'' (Gredler)||||1||1||1||1
|- valign="top"
| ''Barypeithes ?pyrenaeus'' (Seidlitz)||7||4||2||1||7
|- valign="top"
| ''Notaris ?acridulus'' (L.)||1||||||||1
|- valign="top"
| ''Limnobaris pilistriatus'' (Stephens)||1||2||2||1||2
|}

The presence of only a single Elmidae, ''Esolus parallelopipedus'', one of the commonest of British Elmids, is also significant. Analysis of sub-fossil assemblages from Warwickshire (Osborne, 1988) demonstrates that the distribution of even the rarest species of this genus are relicts of once widespread ranges. These beetles live on clasts in well-oxygenated water with stony or gravel beds. Osborne (1988) suggested that the local extinction of such species was caused by the influx of particulate sediment burying the coarse-grained river bed. He proposed that such valley fill was the result of soil erosion initiated by either deforestation or changes in land use management. The absence of Elmidae from the Nether Daugh site may have resulted from similar processes within the Don catchment.

Channel abandonment and aggradation of the floodplain probably represents the only significant geomorphological change of the River Don and its valley since early Holocene valley floor stabilisation. This alluvial aggradation probably occurred during the mid- to late Holocene, in a largely cleared landscape. There is limited evidence of arable activity, mainly indicated by the occurrence of certain Coleoptera.

The age of the organic sediments, at about 4000 14C years BP, corresponds with that of the earliest cereal grain found in north-east Scotland, from Balbridie, near Banchory (information from Aberdeen Art Gallery and Museums Environmental Archaeology Unit, 1989). Furthermore, Edwards (1978) and Edwards and Rowntree (1980) have shown that the late Neolithic and early Bronze Age was a period of human impact on vegetation in north-east Scotland, with large-scale forest clearance resulting in increased sedimentation into lochs on Deeside. There is no evidence for significant climatic changes that may have initiated alluviation (Lamb, 1977). Indeed it appears that Holocene climatic changes were subtle and may have had little effect on erosion except where vegetation cover was removed (Brown, 1987). Hence, the infilling of the channel at Nether Daugh, and the subsequent floodplain aggradation, may be partially a consequence of anthropogenic activity in the Don catchment.

== References ==
[[References, Cainozoic of north-east Scotland|Full reference list]]

[[Category:Grampian Highlands]]
[[Category: 4. Grampian Highlands]]

Crossbrae Farm, Turriff - locality, Cainozoic of north-east Scotland

2015-09-17T09:22:08Z

Lmo:

Knockhill Wood, Glenbervie - locality, Cainozoic of north-east Scotland

2015-09-17T09:19:26Z

Lmo:

'''From: Merritt, J W, Auton, C A, Connell, E R, Hall, A M, and Peacock, J D. 2003. [[Cainozoic geology and landscape evolution of north-east Scotland. Memoir of the British Geological Survey, sheets 66E, 67, 76E, 77, 86E, 87W, 87E, 95, 96W, 96E and 97 (Scotland)|Cainozoic geology and landscape evolution of north-east Scotland]]. Memoir of the British Geological Survey, sheets 66E, 67, 76E, 77, 86E, 87W, 87E, 95, 96W, 96E and 97 (Scotland).'''

= Knockhill Wood, Glenbervie =
[[File:P915380.png|thumbnail|Glacial and glaciofluvial features and the distribution of glacigenic deposits on Sheet 66E Banchory. P915380.]]
A Late-glacial (Windermere) Interstadial peat, intercalated between red-brown diamictons at Knockhill Wood, Glenbervie [[Media:P915380.png|(P915380)]], provides important evidence of the age of slope modification in Strathmore by landslipping. The 14C age, pollen spectra and plant macrofossils obtained from the peat, and its stratigraphical contacts suggest that the last movement occurred either during the Loch Lomond Stadial or when the climate ameliorated, during the earliest Holocene.

[[File:P915329.png|left|thumbnail|Location of Knockhill Wood site. P915329.]]
A composite organic deposit was discovered beneath reddish brown diamicton of the Mearns Drift Group during the resurvey of Sheet 66E Banchory in 1989. The deposits were located in a drainage ditch (NO 7667 8012) on the north-eastern side of a forestry track through Knockhill Wood, on the southern side of the valley of the Bervie Water, upstream of Glenbervie [[Media:P915329.png|(P915329)]]. The organic sediments consisted largely of peat, with subordinate layers of fine peaty sand and laminated clayey silt (see table below). They rested upon an unstratified bouldery till, also reddish brown in colour.

{| class="wikitable"
|+ style="caption-side:top;"|Stratigraphy of the Knockhill Wood site
|-
! Unit||Lithology||Description||Thickness (m)||Depth (m)
|- valign="top"
| A||Landslipped till||'''Diamicton''', stiff, clayey, slightly sandy; moderate reddish brown, 'flecked' with red. Clasts angular to subangular, gravel including decomposed andesite. Slightly irregular gradational base||0.25||0.25
|- valign="top"
| B||Clayey silt||'''Clayey silt''', with sand laminae and thin wisps of peat. Light olive-grey to pale reddish brown. Sharp planar base||0.05||0.30
|- valign="top"
| C||Fibrous peat||'''Peat''', fibrous, compact, with pronounced colour banding on freshly exposed face. Colour ranges from moderate yellowish brown, through dusky yellowish brown to black. Slightly irregular base||0.51||0.81
|- valign="top"
| D||Clayey silt||'''Clayey silt''', micaceous, with fine sand and some peat fragments. Dark yellowish brown to moderate greyish red. Uneven base||0.07||0.88
|- valign="top"
| E||Fibrous peat||'''Peat''', fibrous, dark yellowish brown to dusky yellowish brown||0.10||0.98
|- valign="top"
| F||Silty peat||'''Peat''', silty, laminated, moderate grey||0.06||1.04
|- valign="top"
| G||Sand||'''Sand''', silty and clayey, medium- to coarse- grained, greyish red. Some small peat lenses incorporated towards the base||0.16||1.20
|- valign="top"
| H||Silty peat||'''Peat''', silty and clayey, moderate olive-grey||0.05||1.25
|- valign="top"
| I||Fibrous peat||'''Peat''', fibrous, dark yellowish brown to dusky yellowish brown||0.02||1.27
|- valign="top"
| J||Till||'''Diamicton''', firm, sandy and silty, moderate reddish brown. Clasts rounded to well rounded, large cobbles and boulders derived from Old Red sandstone conglomerates||0.15+||1.42
|}

[[File:P915330.png|left|thumbnail|Knockhill Wood exposure showing the relationship between the organic and glacigenic sediments. P915330.]]
The organic deposits are exposed along about 7 m of the ditch, and appear to form a wedge in the side of Knock Hill [[Media:P915330.png|(P915330)]]. They overlie bouldery till (unit J of table above) and are interstratified with clayey silts and sands. At the north-eastern end of the section, the upper part of the organic sequence (units B–F) is truncated by the overlying clayey diamicton of unit A. This diamicton is hard, but plastic, and apart from flecks of more vivid red clay, it shows little sign of internal stratification. Its base is slightly uneven and gradational over about 1 cm. Other sections lower down the hillside show that the basal till (unit J) reaches up to 8 m in thickness and varies laterally from being stiff and clayey, to friable and sandy. It rests on decomposed feldspathic andesite of the Montrose Volcanic Formation in a river cliff of the Bervie Water (NO 7642 8024).

[[File:P915331.png|thumbnail|Graphic log of the organic sequence at Knockhill Wood. P915331.]]
The base of unit A incorporates wisps and fragments of peat where it overlies the truncated stretch of the organic sequence. The organic sequence itself is penetrated to a depth of about 0.8 m by a vertical, downward-tapering crack filled with red-brown clayey diamicton [[Media:P915330.png|(P915330)]]. The crack is either an ice-wedge pseudomorph, or a vertical fracture that has opened up owing to down-slope gravitational movement. The latter explanation is perhaps more likely as there is no evidence of any reorientation of clasts within the fissure infill, as would be expected if it were of periglacial origin.

Six samples taken from a monolith [[Media:P915331.png|(P915331)]] for pollen analysis by M J C Walker (University of Wales, Lampeter, 1989), yielded relatively sparse assemblages. Only one hundred pollen grains were counted from each sample (see table below). The pollen assemblages suggest an open, essentially treeless landscape, dominated by grass and sedge, with a number of herbaceous taxa present (e.g. ''Compositae, Cruciferae, Rumex ''and ''Caryophyllaceae''). Tree pollen was sparse, although willow pollen was notable towards the bottom of the profile. The treeless nature of the landscape suggested by these assemblages is clearly indicative of interstadial or tundra climate, rather than warmer interglacial conditions.

{| class="wikitable"
|+ style="caption-side:top;"|Outline pollen count from Knockhill Wood
|-
! scope="row" colspan="2"|Sample||6||5||4||3||2||1
|-
! scope="row" colspan="2"|Depth (cm)
|25-30||45-50||57-67||81-84||97-104||104-107
|-
! scope="row" rowspan="2" |Trees
|''Betula'' (birch)||1||1||1||1||||
|- style="vertical-align:top;"rowspan="1"| rowspan="1"
|''Pinus'' (pine)||1||||||1||2||2
|-
! scope="row" rowspan="4" |Shrubs/ dwarf shrubs
|''Corylus'' (hazel)||||||||||1||
|-
|''Salix'' (willow)||1||1||||4||4||7
|-
|Ericaceae (heather)||2||1||||||||
|-
|''Empetrum'' (crowberry)||||1||3||||||
|-
! scope="row" rowspan="1" |Grass
|Gramineae||28||14||14||26||32||28
|-
! scope="row" rowspan="1" |Sedges
|Cyperaceae||54||75||65||34||34||34
|-
! scope="row" rowspan="9" |Herbaceous taxa
|Compositae: Liguilflorae (daisy)||||1||1||4||1||1
|-
|Compositae: Tubliflorae (daisy)||||||1||19||||
|-
|Caryophyllaceae (pinks)||||1||3||1||1||
|-
|Cruciferae (brassica)||||1||4||2||11||12
|-
|''Epilobium'' (willowherb)||||||||||1||1
|-
|''Ranunculus'' (buttercup)||||||||2||1||1
|-
|''Rumex'' (docks)||10||||3||2||3||8
|-
|''Thalictrum'' (meadow-rues)||||1||1||||4||
|-
|''Artemesia'' (mugworts)||1||||||||2||
|-
! scope="row" rowspan="2" |Aquatics
|''Myriophyllum'' (water-milfoils)||||1||||||||
|-
|''Potamogeton'' (pondweeds)||||||||3||1||
|-
! scope="row" rowspan="4" |Spores
|Filicales||||||5||10||11||7
|-
|''Lycopodium''||||4||||||||
|-
|''Lycopodium selago''||||1||||||||
|-
|''Sphagnum''||165||||||||||
|-
! scope="row" colspan="2"|Indeterminate
|2||2||3||4||3||6
|}

The climatic inferences from the pollen analyses were supported by the results of plant macrofossil analysis by M Field (Keele University, 1991) (see [[Media:P915331.png|P915331]] for sampling intervals). Sample B9 yielded 34 compressed ''Carex ''(sedge) fruits. Sample B10 yielded a well-preserved assemblage of macrofossils, but revealed the presence of only three taxa. A single seed of ''Viola ''sp. (violet), 81 compressed ''Carex ''fruits and hundreds of seeds of ''Monitia fontana ''subspecies ''fontana'', a herbaceous annual to perennial of the ‘Blinks’ family (Stace, 1991) were recorded. The latter form is widely distributed at present in northern Britain and reaches north-westwards into northern Scandinavia. It occurs in damp habitats and its occurrence with ''Carex ''suggests a damp open landscape.

An initial radiocarbon age (GX–14723) of 12 460 ± 130 14C years BP was obtained for an acid-washed bulk sample of the silty peat. A sample taken subsequently was pre-treated to separate the alkali soluble (humic) and alkali insoluble (humin) components for independent age measurement. This was undertaken in order to identify any younger contaminants not completely removed by the pre-treatment. An age of 12 305 ± 50 14C years BP was obtained for the humic component (SRR–3687a) and 12 340 ± 50 14C years BP for the humin component (SRR–3687b) (see table below). All of the radiocarbon dates indicate a Late-glacial Interstadial age for the lower part of the sequence. It is possible that the upper parts of the organic sequence may extend into the succeeding Loch Lomond Stadial, but at present, the evidence from the flora is inconclusive.

{| class="wikitable"
|+ style="caption-side:top;"|Radiocarbon dates from Late-glacial sites in the district
|-
! Site||Grid reference||Laboratory number||Age (year BP)||Dated material and setting||Reference
|-
| Rothes cutting||NJ 277 498||Beta 8653||11 110 ± 70||peat under remobilised till||Appendix 1
|-
| Garral Hill, Keith||NJ 444 551||Q-104||10 808 ± 230||peat under remobilised till||Godwin and Willis (1959)
|-
| Garral Hill, Keith||NJ 444 551||Q-103||11 098 ± 235||peat under remobilised till||Godwin and Willis (1959)
|-
| Garral Hill, Keith||NJ 444 551||Q-102||11 308 ± 245||peat under remobilised till||Godwin and Willis (1959)
|-
| Garral Hill, Keith||NJ 444 551||Q-101||11 888 ± 225||peat under remobilised till||Godwin and Willis (1959)
|-
| Garral Hill, Keith||NJ 444 551||Q-100||11 358 ± 300||peat under remobilised till||Godwin and Willis (1959)
|-
| Woodhead, Fyvie||NJ 788 384||SRR-1723||10 780 ± 50||peat under remobilised till||Connell and Hall (1987)
|-
| Howe of Byth||NJ 822 571||SRR-4830||11320||peat beneath gravel||Hall et al. (1995)
|-
| Moss-side, Tarves||NJ 833 318||I-6969||12 200 ± 170||peat under remobilised till||Clapperton and Sugden (1977)
|-
| Loch of Park||NO 772 988||HEL-416||10 280 ± 220||kettlehole infill||Vasari and Vasari (1968)
|-
| Loch of Park||||HEL-417||11 900 ± 260||kettlehole infill||Vasari and Vasari (1968)
|-
| Mill of Dyce||NJ 8713 1496||SRR-762||11 550 ± 80||kettlehole infill||Harkness and Wilson (1979)
|-
| Mill of Dyce||NJ 8713 1496||SRR-763||11 640 ± 70||kettlehole infill||Harkness and Wilson (1979)
|-
| Glenbervie||NO 767 801||GX-14723||12 460 ± 130||peat under remobilised till||Appendix 1
|-
| Glenbervie||NO 767 801||SRR-3687a. (humic)||12 305 ± 50||peat under remobilised till||Appendix 1
|-
| Glenbervie||NO 767 801||SRR-368Th (humin)||12 340 ± 50||peat under remobilised till||Appendix 1
|-
| Brinzieshill Farm||NO 7936 7918||SRR-387||12 390 ± 100||peat under remobilised till||Auton et al. (2000)
|-
| Rothens||NJ 688 171||SRR-3803||10 680 ± 100||kettlehole infill||Appendix 1
|-
| Rothens||NJ 688 171||SRR-3804||11 640 ± 160||kettlehole infill||Appendix 1
|-
| Rothens||NJ 688 171||SRR-3805||11 760 ± 140||kettlehole infill||Appendix 1
|}

The stratigraphical, sedimentological and palaeontological studies of the sequence at Knockhill Wood and the radiocarbon dates suggest that the organic sediments were laid down in a cool damp environment, during the Late-glacial (Windermere) Interstadial. The organic sequence overlies a basal bouldery lodgement till of probable main Late Devensian age, laid down on top of weathered andesite bedrock. The basal till is assigned to the Mill of Forest Till Formation. The origin of the overlying matrix-supported clayey diamicton is more problematic. Its compact structure and absence of well-developed internal stratification are typical attributes of lodgement or deforming-bed tills, rather than flow tills. No tills of Loch Lomond Stadial age are known from the district. Indeed, dating and palynological evidence from sites such as the Loch of Park indicate that the low ground was deglaciated throughout the Loch Lomond Stadial.

[[File:P915332.png|thumbnail|Postulated form of the landslip Knockhill Wood. P915332.]]
The upper diamicton has a gradational, but apparently conformable contact with the underlying organic sediments in the south-western part of the Knockhill Wood section, but it sharply truncates the upper part of the same sequence at the north-eastern (downslope) end of the exposure. This cross-cutting relationship, together with incorporation of fragments of peat in the till near the truncation surface, suggest that the diamicton has been emplaced as part of a landslip. The slip occurred by downslope movement along a gently curved, low-angle plane at the top of the laminated clayey silts [[Media:P915332.png|(P915332)]]. It is likely that slipping also occurred at the till/bedrock contact. If the tapering feature cutting the organic sequence is an ice-wedge cast, its presence would suggest that the movement probably occurred immediately following the Loch Lomond Stadial when rapid climatic amelioration took place.

== References ==
[[References, Cainozoic of north-east Scotland|Full reference list]]

[[Category:Grampian Highlands]]
[[Category: 4. Grampian Highlands]]

Knockhill Wood, Glenbervie - locality, Cainozoic of north-east Scotland

2015-09-17T08:58:28Z

Lmo:

'''From: Merritt, J W, Auton, C A, Connell, E R, Hall, A M, and Peacock, J D. 2003. [[Cainozoic geology and landscape evolution of north-east Scotland. Memoir of the British Geological Survey, sheets 66E, 67, 76E, 77, 86E, 87W, 87E, 95, 96W, 96E and 97 (Scotland)|Cainozoic geology and landscape evolution of north-east Scotland]]. Memoir of the British Geological Survey, sheets 66E, 67, 76E, 77, 86E, 87W, 87E, 95, 96W, 96E and 97 (Scotland).'''

= Knockhill Wood, Glenbervie =
[[File:P915380.png|thumbnail|Glacial and glaciofluvial features and the distribution of glacigenic deposits on Sheet 66E Banchory. P915380.]]
A Late-glacial (Windermere) Interstadial peat, intercalated between red-brown diamictons at Knockhill Wood, Glenbervie [[Media:P915380.png|(P915380)]], provides important evidence of the age of slope modification in Strathmore by landslipping. The 14C age, pollen spectra and plant macrofossils obtained from the peat, and its stratigraphical contacts suggest that the last movement occurred either during the Loch Lomond Stadial or when the climate ameliorated, during the earliest Holocene.

[[File:P915329.png|left|thumbnail|Location of Knockhill Wood site. P915329.]]
A composite organic deposit was discovered beneath reddish brown diamicton of the Mearns Drift Group during the resurvey of Sheet 66E Banchory in 1989. The deposits were located in a drainage ditch (NO 7667 8012) on the north-eastern side of a forestry track through Knockhill Wood, on the southern side of the valley of the Bervie Water, upstream of Glenbervie [[Media:P915329.png|(P915329)]]. The organic sediments consisted largely of peat, with subordinate layers of fine peaty sand and laminated clayey silt (see table below). They rested upon an unstratified bouldery till, also reddish brown in colour.

{| class="wikitable"
|+ style="caption-side:top;"|Stratigraphy of the Knockhill Wood site
|-
! Unit||Lithology||Description||Thickness (m)||Depth (m)
|- valign="top"
| A||Landslipped till||'''Diamicton''', stiff, clayey, slightly sandy; moderate reddish brown, 'flecked' with red. Clasts angular to subangular, gravel including decomposed andesite. Slightly irregular gradational base||0.25||0.25
|- valign="top"
| B||Clayey silt||'''Clayey silt''', with sand laminae and thin wisps of peat. Light olive-grey to pale reddish brown. Sharp planar base||0.05||0.30
|- valign="top"
| C||Fibrous peat||'''Peat''', fibrous, compact, with pronounced colour banding on freshly exposed face. Colour ranges from moderate yellowish brown, through dusky yellowish brown to black. Slightly irregular base||0.51||0.81
|- valign="top"
| D||Clayey silt||'''Clayey silt''', micaceous, with fine sand and some peat fragments. Dark yellowish brown to moderate greyish red. Uneven base||0.07||0.88
|- valign="top"
| E||Fibrous peat||'''Peat''', fibrous, dark yellowish brown to dusky yellowish brown||0.10||0.98
|- valign="top"
| F||Silty peat||'''Peat''', silty, laminated, moderate grey||0.06||1.04
|- valign="top"
| G||Sand||'''Sand''', silty and clayey, medium- to coarse- grained, greyish red. Some small peat lenses incorporated towards the base||0.16||1.20
|- valign="top"
| H||Silty peat||'''Peat''', silty and clayey, moderate olive-grey||0.05||1.25
|- valign="top"
| I||Fibrous peat||'''Peat''', fibrous, dark yellowish brown to dusky yellowish brown||0.02||1.27
|- valign="top"
| J||Till||'''Diamicton''', firm, sandy and silty, moderate reddish brown. Clasts rounded to well rounded, large cobbles and boulders derived from Old Red sandstone conglomerates||0.15+||1.42
|}

[[File:P915330.png|left|thumbnail|Knockhill Wood exposure showing the relationship between the organic and glacigenic sediments. P915330.]]
The organic deposits are exposed along about 7 m of the ditch, and appear to form a wedge in the side of Knock Hill [[Media:P915330.png|(P915330)]]. They overlie bouldery till (unit J of table above) and are interstratified with clayey silts and sands. At the north-eastern end of the section, the upper part of the organic sequence (units B–F) is truncated by the overlying clayey diamicton of unit A. This diamicton is hard, but plastic, and apart from flecks of more vivid red clay, it shows little sign of internal stratification. Its base is slightly uneven and gradational over about 1 cm. Other sections lower down the hillside show that the basal till (unit J) reaches up to 8 m in thickness and varies laterally from being stiff and clayey, to friable and sandy. It rests on decomposed feldspathic andesite of the Montrose Volcanic Formation in a river cliff of the Bervie Water (NO 7642 8024).

[[File:P915331.png|thumbnail|Graphic log of the organic sequence at Knockhill Wood. P915331.]]
The base of unit A incorporates wisps and fragments of peat where it overlies the truncated stretch of the organic sequence. The organic sequence itself is penetrated to a depth of about 0.8 m by a vertical, downward-tapering crack filled with red-brown clayey diamicton [[Media:P915330.png|(P915330)]]. The crack is either an ice-wedge pseudomorph, or a vertical fracture that has opened up owing to down-slope gravitational movement. The latter explanation is perhaps more likely as there is no evidence of any reorientation of clasts within the fissure infill, as would be expected if it were of periglacial origin.

Six samples taken from a monolith [[Media:P915331.png|(P915331)]] for pollen analysis by M J C Walker (University of Wales, Lampeter, 1989), yielded relatively sparse assemblages. Only one hundred pollen grains were counted from each sample (see table below). The pollen assemblages suggest an open, essentially treeless landscape, dominated by grass and sedge, with a number of herbaceous taxa present (e.g. ''Compositae, Cruciferae, Rumex ''and ''Caryophyllaceae''). Tree pollen was sparse, although willow pollen was notable towards the bottom of the profile. The treeless nature of the landscape suggested by these assemblages is clearly indicative of interstadial or tundra climate, rather than warmer interglacial conditions.

{| class="wikitable"
|+ style="caption-side:top;"|Outline pollen count from Knockhill Wood
|-
! scope="row" colspan="2"|Sample||6||5||4||3||2||1
|-
! scope="row" colspan="2"|Depth (cm)
|25-30||45-50||57-67||81-84||97-104||104-107
|-
! scope="row" rowspan="2" |Trees
|''Betula'' (birch)||1||1||1||1||||
|- style="vertical-align:top;"rowspan="1"| rowspan="1"
|''Pinus'' (pine)||1||||||1||2||2
|-
! scope="row" rowspan="4" |Shrubs/ dwarf shrubs
|''Corylus'' (hazel)||||||||||1||
|-
|''Salix'' (willow)||1||1||||4||4||7
|-
|Ericaceae (heather)||2||1||||||||
|-
|''Empetrum'' (crowberry)||||1||3||||||
|-
! scope="row" rowspan="1" |Grass
|Gramineae||28||14||14||26||32||28
|-
! scope="row" rowspan="1" |Sedges
|Cyperaceae||54||75||65||34||34||34
|-
! scope="row" rowspan="9" |Herbaceous taxa
|Compositae: Liguilflorae (daisy)||||1||1||4||1||1
|-
|Compositae: Tubliflorae (daisy)||||||1||19||||
|-
|Caryophyllaceae (pinks)||||1||3||1||1||
|-
|Cruciferae (brassica)||||1||4||2||11||12
|-
|''Epilobium'' (willowherb)||||||||||1||1
|-
|''Ranunculus'' (buttercup)||||||||2||1||1
|-
|''Rumex'' (docks)||10||||3||2||3||8
|-
|''Thalictrum'' (meadow-rues)||||1||1||||4||
|-
|''Artemesia'' (mugworts)||1||||||||2||
|-
! scope="row" rowspan="2" |Aquatics
|''Myriophyllum'' (water-milfoils)||||1||||||||
|-
|''Potamogeton'' (pondweeds)||||||||3||1||
|-
! scope="row" rowspan="4" |Spores
|Filicales||||||5||10||11||7
|-
|''Lycopodium''||||4||||||||
|-
|''Lycopodium selago''||||1||||||||
|-
|''Sphagnum''||165||||||||||
|-
! scope="row" colspan="2"|Indeterminate
|2||2||3||4||3||6
|}

The climatic inferences from the pollen analyses were supported by the results of plant macrofossil analysis by M Field (Keele University, 1991) (see [[Media:P915331.png|P915331]] for sampling intervals). Sample B9 yielded 34 compressed ''Carex ''(sedge) fruits. Sample B10 yielded a well-preserved assemblage of macrofossils, but revealed the presence of only three taxa. A single seed of ''Viola ''sp. (violet), 81 compressed ''Carex ''fruits and hundreds of seeds of ''Monitia fontana ''subspecies ''fontana'', a herbaceous annual to perennial of the ‘Blinks’ family (Stace, 1991) were recorded. The latter form is widely distributed at present in northern Britain and reaches north-westwards into northern Scandinavia. It occurs in damp habitats and its occurrence with ''Carex ''suggests a damp open landscape.

An initial radiocarbon age (GX–14723) of 12 460 ± 130 14C years BP was obtained for an acid-washed bulk sample of the silty peat. A sample taken subsequently was pre-treated to separate the alkali soluble (humic) and alkali insoluble (humin) components for independent age measurement. This was undertaken in order to identify any younger contaminants not completely removed by the pre-treatment. An age of 12 305 ± 50 14C years BP was obtained for the humic component (SRR–3687a) and 12 340 ± 50 14C years BP for the humin component (SRR–3687b) (see table below). All of the radiocarbon dates indicate a Late-glacial Interstadial age for the lower part of the sequence. It is possible that the upper parts of the organic sequence may extend into the succeeding Loch Lomond Stadial, but at present, the evidence from the flora is inconclusive.

{| class="wikitable"
|+ style="caption-side:top;"|Radiocarbon dates from Late-glacial sites in the district
|-
! Site||Grid reference||Laboratory number||Age (year BP)||Dated material and setting||Reference
|-
| Rothes cutting||NJ 277 498||Beta 8653||11 110 ± 70||peat under remobilised till||Appendix 1
|-
| Garral Hill, Keith||NJ 444 551||Q-104||10 808 ± 230||peat under remobilised till||Godwin and Willis (1959)
|-
| Garral Hill, Keith||NJ 444 551||Q-103||11 098 ± 235||peat under remobilised till||Godwin and Willis (1959)
|-
| Garral Hill, Keith||NJ 444 551||Q-102||11 308 ± 245||peat under remobilised till||Godwin and Willis (1959)
|-
| Garral Hill, Keith||NJ 444 551||Q-101||11 888 ± 225||peat under remobilised till||Godwin and Willis (1959)
|-
| Garral Hill, Keith||NJ 444 551||Q-100||11 358 ± 300||peat under remobilised till||Godwin and Willis (1959)
|-
| Woodhead, Fyvie||NJ 788 384||SRR-1723||10 780 ± 50||peat under remobilised till||Connell and Hall (1987)
|-
| Howe of Byth||NJ 822 571||SRR-4830||11320||peat beneath gravel||Hall et al. (1995)
|-
| Moss-side, Tarves||NJ 833 318||I-6969||12 200 ± 170||peat under remobilised till||Clapperton and Sugden (1977)
|-
| Loch of Park||NO 772 988||HEL-416||10 280 ± 220||kettlehole infill||Vasari and Vasari (1968)
|-
| Loch of Park||||HEL-417||11 900 ± 260||kettlehole infill||Vasari and Vasari (1968)
|-
| Mill of Dyce||NJ 8713 1496||SRR-762||11 550 ± 80||kettlehole infill||Harkness and Wilson (1979)
|-
| Mill of Dyce||NJ 8713 1496||SRR-763||11 640 ± 70||kettlehole infill||Harkness and Wilson (1979)
|-
| Glenbervie||NO 767 801||GX-14723||12 460 ± 130||peat under remobilised till||Appendix 1
|-
| Glenbervie||NO 767 801||SRR-3687a. (humic)||12 305 ± 50||peat under remobilised till||Appendix 1
|-
| Glenbervie||NO 767 801||SRR-368Th (humin)||12 340 ± 50||peat under remobilised till||Appendix 1
|-
| Brinzieshill Farm||NO 7936 7918||SRR-387||12 390 ± 100||peat under remobilised till||Auton et al. (2000)
|-
| Rothens||NJ 688 171||SRR-3803||10 680 ± 100||kettlehole infill||Appendix 1
|-
| Rothens||NJ 688 171||SRR-3804||11 640 ± 160||kettlehole infill||Appendix 1
|-
| Rothens||NJ 688 171||SRR-3805||11 760 ± 140||kettlehole infill||Appendix 1
|}

The stratigraphical, sedimentological and palaeontological studies of the sequence at Knockhill Wood and the radiocarbon dates suggest that the organic sediments were laid down in a cool damp environment, during the Late-glacial (Windermere) Interstadial. The organic sequence overlies a basal bouldery lodgement till of probable main Late Devensian age, laid down on top of weathered andesite bedrock. The basal till is assigned to the Mill of Forest Till Formation. The origin of the overlying matrix-supported clayey diamicton is more problematic. Its compact structure and absence of well-developed internal stratification are typical attributes of lodgement or deforming-bed tills, rather than flow tills. No tills of Loch Lomond Stadial age are known from the district. Indeed, dating and palynological evidence from sites such as the Loch of Park indicate that the low ground was deglaciated throughout the Loch Lomond Stadial.

[[File:P915332.png|thumbnail|Postulated form of the landslip Knockhill Wood. P915332.]]
The upper diamicton has a gradational, but apparently conformable contact with the underlying organic sediments in the south-western part of the Knockhill Wood section, but it sharply truncates the upper part of the same sequence at the north-eastern (downslope) end of the exposure. This cross-cutting relationship, together with incorporation of fragments of peat in the till near the truncation surface, suggest that the diamicton has been emplaced as part of a landslip. The slip occurred by downslope movement along a gently curved, low-angle plane at the top of the laminated clayey silts [[Media:P915332.png|(P915332)]]. It is likely that slipping also occurred at the till/bedrock contact. If the tapering feature cutting the organic sequence is an ice-wedge cast, its presence would suggest that the movement probably occurred immediately following the Loch Lomond Stadial when rapid climatic amelioration took place.

== References ==
[[References, Cainozoic of north-east Scotland|Full reference list]]

[[Category:Grampian Highlands]]
[[Category: 4. Grampian Highlands]]

Knockhill Wood, Glenbervie - locality, Cainozoic of north-east Scotland

2015-09-17T08:06:31Z

Lmo:

'''From: Merritt, J W, Auton, C A, Connell, E R, Hall, A M, and Peacock, J D. 2003. [[Cainozoic geology and landscape evolution of north-east Scotland. Memoir of the British Geological Survey, sheets 66E, 67, 76E, 77, 86E, 87W, 87E, 95, 96W, 96E and 97 (Scotland)|Cainozoic geology and landscape evolution of north-east Scotland]]. Memoir of the British Geological Survey, sheets 66E, 67, 76E, 77, 86E, 87W, 87E, 95, 96W, 96E and 97 (Scotland).'''

= Knockhill Wood, Glenbervie =
[[File:P915380.png|thumbnail|Glacial and glaciofluvial features and the distribution of glacigenic deposits on Sheet 66E Banchory. P915380.]]
A Late-glacial (Windermere) Interstadial peat, intercalated between red-brown diamictons at Knockhill Wood, Glenbervie [[Media:P915380.png|(P915380)]], provides important evidence of the age of slope modification in Strathmore by landslipping. The 14C age, pollen spectra and plant macrofossils obtained from the peat, and its stratigraphical contacts suggest that the last movement occurred either during the Loch Lomond Stadial or when the climate ameliorated, during the earliest Holocene.

[[File:P915329.png|left|thumbnail|Location of Knockhill Wood site. P915329.]]
A composite organic deposit was discovered beneath reddish brown diamicton of the Mearns Drift Group during the resurvey of Sheet 66E Banchory in 1989. The deposits were located in a drainage ditch (NO 7667 8012) on the north-eastern side of a forestry track through Knockhill Wood, on the southern side of the valley of the Bervie Water, upstream of Glenbervie [[Media:P915329.png|(P915329)]]. The organic sediments consisted largely of peat, with subordinate layers of fine peaty sand and laminated clayey silt (see table below). They rested upon an unstratified bouldery till, also reddish brown in colour.

{| class="wikitable"
|+ style="caption-side:top;"|Stratigraphy of the Knockhill Wood site
|-
! Unit||Lithology||Description||Thickness (m)||Depth (m)
|- valign="top"
| A||Landslipped till||'''Diamicton''', stiff, clayey, slightly sandy; moderate reddish brown, 'flecked' with red. Clasts angular to subangular, gravel including decomposed andesite. Slightly irregular gradational base||0.25||0.25
|- valign="top"
| B||Clayey silt||'''Clayey silt''', with sand laminae and thin wisps of peat. Light olive-grey to pale reddish brown. Sharp planar base||0.05||0.30
|- valign="top"
| C||Fibrous peat||'''Peat''', fibrous, compact, with pronounced colour banding on freshly exposed face. Colour ranges from moderate yellowish brown, through dusky yellowish brown to black. Slightly irregular base||0.51||0.81
|- valign="top"
| D||Clayey silt||'''Clayey silt''', micaceous, with fine sand and some peat fragments. Dark yellowish brown to moderate greyish red. Uneven base||0.07||0.88
|- valign="top"
| E||Fibrous peat||'''Peat''', fibrous, dark yellowish brown to dusky yellowish brown||0.10||0.98
|- valign="top"
| F||Silty peat||'''Peat''', silty, laminated, moderate grey||0.06||1.04
|- valign="top"
| G||Sand||'''Sand''', silty and clayey, medium- to coarse- grained, greyish red. Some small peat lenses incorporated towards the base||0.16||1.20
|- valign="top"
| H||Silty peat||'''Peat''', silty and clayey, moderate olive-grey||0.05||1.25
|- valign="top"
| I||Fibrous peat||'''Peat''', fibrous, dark yellowish brown to dusky yellowish brown||0.02||1.27
|- valign="top"
| J||Till||'''Diamicton''', firm, sandy and silty, moderate reddish brown. Clasts rounded to well rounded, large cobbles and boulders derived from Old Red sandstone conglomerates||0.15+||1.42
|}

[[File:P915330.png|thumbnail|Knockhill Wood exposure showing the relationship between the organic and glacigenic sediments. P915330.]]
The organic deposits are exposed along about 7 m of the ditch, and appear to form a wedge in the side of Knock Hill [[Media:P915330.png|(P915330)]]. They overlie bouldery till (unit J of table above) and are interstratified with clayey silts and sands. At the north-eastern end of the section, the upper part of the organic sequence (units B–F) is truncated by the overlying clayey diamicton of unit A. This diamicton is hard, but plastic, and apart from flecks of more vivid red clay, it shows little sign of internal stratification. Its base is slightly uneven and gradational over about 1 cm. Other sections lower down the hillside show that the basal till (unit J) reaches up to 8 m in thickness and varies laterally from being stiff and clayey, to friable and sandy. It rests on decomposed feldspathic andesite of the Montrose Volcanic Formation in a river cliff of the Bervie Water (NO 7642 8024).

The base of unit A incorporates wisps and fragments of peat where it overlies the truncated stretch of the organic sequence. The organic sequence itself is penetrated to a depth of about 0.8 m by a vertical, downward-tapering crack filled with red-brown clayey diamicton [[Media:P915330.png|(P915330)]]. The crack is either an ice-wedge pseudomorph, or a vertical fracture that has opened up owing to down-slope gravitational movement. The latter explanation is perhaps more likely as there is no evidence of any reorientation of clasts within the fissure infill, as would be expected if it were of periglacial origin.

[[File:P915331.png|left|thumbnail|Graphic log of the organic sequence at Knockhill Wood. P915331.]]
[[File:P915315.png|thumbnail|Schematic stratigraphical relationships in the Sandford Bay area. P915315.]]
Six samples taken from a monolith [[Media:P915331.png|(P915331)]] for pollen analysis by M J C Walker (University of Wales, Lampeter, 1989), yielded relatively sparse assemblages. Only one hundred pollen grains were counted from each sample [[Media:P915315.png|(P915315)]]. The pollen assemblages suggest an open, essentially treeless landscape, dominated by grass and sedge, with a number of herbaceous taxa present (e.g. ''Compositae, Cruciferae, Rumex ''and ''Caryophyllaceae''). Tree pollen was sparse, although willow pollen was notable towards the bottom of the profile. The treeless nature of the landscape suggested by these assemblages is clearly indicative of interstadial or tundra climate, rather than warmer interglacial conditions.

The climatic inferences from the pollen analyses were supported by the results of plant macrofossil analysis by M Field (Keele University, 1991) (see [[Media:P915331.png|P915331]] for sampling intervals). Sample B9 yielded 34 compressed ''Carex ''(sedge) fruits. Sample B10 yielded a well-preserved assemblage of macrofossils, but revealed the presence of only three taxa. A single seed of ''Viola ''sp. (violet), 81 compressed ''Carex ''fruits and hundreds of seeds of ''Monitia fontana ''subspecies ''fontana'', a herbaceous annual to perennial of the ‘Blinks’ family (Stace, 1991) were recorded. The latter form is widely distributed at present in northern Britain and reaches north-westwards into northern Scandinavia. It occurs in damp habitats and its occurrence with ''Carex ''suggests a damp open landscape.

An initial radiocarbon age (GX–14723) of 12 460 ± 130 14C years BP was obtained for an acid-washed bulk sample of the silty peat. A sample taken subsequently was pre-treated to separate the alkali soluble (humic) and alkali insoluble (humin) components for independent age measurement. This was undertaken in order to identify any younger contaminants not completely removed by the pre-treatment. An age of 12 305 ± 50 14C years BP was obtained for the humic component (SRR–3687a) and 12 340 ± 50 14C years BP for the humin component (SRR–3687b) (see table below). All of the radiocarbon dates indicate a Late-glacial Interstadial age for the lower part of the sequence. It is possible that the upper parts of the organic sequence may extend into the succeeding Loch Lomond Stadial, but at present, the evidence from the flora is inconclusive.

{| class="wikitable"
|+ style="caption-side:top;"|Radiocarbon dates from Late-glacial sites in the district
|-
! Site||Grid reference||Laboratory number||Age (year BP)||Dated material and setting||Reference
|-
| Rothes cutting||NJ 277 498||Beta 8653||11 110 ± 70||peat under remobilised till||Appendix 1
|-
| Garral Hill, Keith||NJ 444 551||Q-104||10 808 ± 230||peat under remobilised till||Godwin and Willis (1959)
|-
| Garral Hill, Keith||NJ 444 551||Q-103||11 098 ± 235||peat under remobilised till||Godwin and Willis (1959)
|-
| Garral Hill, Keith||NJ 444 551||Q-102||11 308 ± 245||peat under remobilised till||Godwin and Willis (1959)
|-
| Garral Hill, Keith||NJ 444 551||Q-101||11 888 ± 225||peat under remobilised till||Godwin and Willis (1959)
|-
| Garral Hill, Keith||NJ 444 551||Q-100||11 358 ± 300||peat under remobilised till||Godwin and Willis (1959)
|-
| Woodhead, Fyvie||NJ 788 384||SRR-1723||10 780 ± 50||peat under remobilised till||Connell and Hall (1987)
|-
| Howe of Byth||NJ 822 571||SRR-4830||11320||peat beneath gravel||Hall et al. (1995)
|-
| Moss-side, Tarves||NJ 833 318||I-6969||12 200 ± 170||peat under remobilised till||Clapperton and Sugden (1977)
|-
| Loch of Park||NO 772 988||HEL-416||10 280 ± 220||kettlehole infill||Vasari and Vasari (1968)
|-
| Loch of Park||||HEL-417||11 900 ± 260||kettlehole infill||Vasari and Vasari (1968)
|-
| Mill of Dyce||NJ 8713 1496||SRR-762||11 550 ± 80||kettlehole infill||Harkness and Wilson (1979)
|-
| Mill of Dyce||NJ 8713 1496||SRR-763||11 640 ± 70||kettlehole infill||Harkness and Wilson (1979)
|-
| Glenbervie||NO 767 801||GX-14723||12 460 ± 130||peat under remobilised till||Appendix 1
|-
| Glenbervie||NO 767 801||SRR-3687a. (humic)||12 305 ± 50||peat under remobilised till||Appendix 1
|-
| Glenbervie||NO 767 801||SRR-368Th (humin)||12 340 ± 50||peat under remobilised till||Appendix 1
|-
| Brinzieshill Farm||NO 7936 7918||SRR-387||12 390 ± 100||peat under remobilised till||Auton et al. (2000)
|-
| Rothens||NJ 688 171||SRR-3803||10 680 ± 100||kettlehole infill||Appendix 1
|-
| Rothens||NJ 688 171||SRR-3804||11 640 ± 160||kettlehole infill||Appendix 1
|-
| Rothens||NJ 688 171||SRR-3805||11 760 ± 140||kettlehole infill||Appendix 1
|}

The stratigraphical, sedimentological and palaeontological studies of the sequence at Knockhill Wood and the radiocarbon dates suggest that the organic sediments were laid down in a cool damp environment, during the Late-glacial (Windermere) Interstadial. The organic sequence overlies a basal bouldery lodgement till of probable main Late Devensian age, laid down on top of weathered andesite bedrock. The basal till is assigned to the Mill of Forest Till Formation. The origin of the overlying matrix-supported clayey diamicton is more problematic. Its compact structure and absence of well-developed internal stratification are typical attributes of lodgement or deforming-bed tills, rather than flow tills. No tills of Loch Lomond Stadial age are known from the district. Indeed, dating and palynological evidence from sites such as the Loch of Park indicate that the low ground was deglaciated throughout the Loch Lomond Stadial.

[[File:P915332.png|thumbnail|Postulated form of the landslip Knockhill Wood. P915332.]]
The upper diamicton has a gradational, but apparently conformable contact with the underlying organic sediments in the south-western part of the Knockhill Wood section, but it sharply truncates the upper part of the same sequence at the north-eastern (downslope) end of the exposure. This cross-cutting relationship, together with incorporation of fragments of peat in the till near the truncation surface, suggest that the diamicton has been emplaced as part of a landslip. The slip occurred by downslope movement along a gently curved, low-angle plane at the top of the laminated clayey silts [[Media:P915332.png|(P915332)]]. It is likely that slipping also occurred at the till/bedrock contact. If the tapering feature cutting the organic sequence is an ice-wedge cast, its presence would suggest that the movement probably occurred immediately following the Loch Lomond Stadial when rapid climatic amelioration took place.

== References ==
[[References, Cainozoic of north-east Scotland|Full reference list]]

{| class="wikitable"
|+ style="caption-side:top;"|Outline pollen count from Knockhill Wood
|-
! Sample||||6||5||4||3||2||1
|-
| '''Depth (cm)'''||||25-30||45-50||57-67||81-84||97-104||104-107
|-
| '''Trees'''||''Betula'' (birch)||1||1||1||1||||
|-
| ||''Pinus'' (pine)||1||||||1||2||2
|-
| '''Shrubs/ dwarf shrubs'''||''Corylus'' (hazel)||||||||||1||
|-
| ||''Salix'' (willow)||1||1||||4||4||7
|-
| ||Ericaceae (heather)||2||1||||||||
|-
| ||''Empetrum'' (crowberry)||||1||3||||||
|-
| '''Grass'''||Gramineae||28||14||14||26||32||28
|-
| '''Sedges'''||Cyperaceae||54||75||65||34||34||34
|-
| '''Herbaceous taxa'''||Compositae: Liguilflorae (daisy)||||1||1||4||1||1
|-
| ||Compositae: Tubliflorae (daisy)||||||1||19||||
|-
| ||Caryophyllaceae (pinks)||||1||3||1||1||
|-
| ||Cruciferae (brassica)||||1||4||2||11||12
|-
| ||''Epilobium'' (willowherb)||||||||||1||1
|-
| ||''Ranunculus'' (buttercup)||||||||2||1||1
|-
| ||''Rumex'' (docks)||10||||3||2||3||8
|-
| ||''Thalictrum'' (meadow-rues)||||1||1||||4||
|-
| ||''Artemesia'' (mugworts)||1||||||||2||
|-
| '''Aquatics'''||''Myriophyllum'' (water-milfoils)||||1||||||||
|-
| ||''Potamogeton'' (pondweeds)||||||||3||1||
|-
| '''Spores'''||Filicales||||||5||10||11||7
|-
| ||''Lycopodium''||||4||||||||
|-
| ||''Lycopodium selago''||||1||||||||
|-
| ||''Sphagnum''||165||||||||||
|-
| '''Indeterminate'''||||2||2||3||4||3||6
|}

[[Category:Grampian Highlands]]
[[Category: 4. Grampian Highlands]]

Category:Grampian Highlands

2015-09-17T07:51:11Z

Lmo:

Many of the articles in this category are derived from the following BGS publications:
::[[British regional geology: Grampian Highlands|Grampian Highlands regional guide]]
::[[Cainozoic geology and landscape evolution of north-east Scotland. Memoir of the British Geological Survey, sheets 66E, 67, 76E, 77, 86E, 87W, 87E, 95, 96W, 96E and 97 (Scotland)|Cainozoic geology and landscape evolution of north-east Scotland]]

<gallery mode=packed heights ="150px">

File:P749349.jpg|[[British regional geology: Grampian Highlands|Link]]
File:P915245.jpg|[[Cainozoic geology and landscape evolution of north-east Scotland. Memoir of the British Geological Survey, sheets 66E, 67, 76E, 77, 86E, 87W, 87E, 95, 96W, 96E and 97 (Scotland)|Link]]

</gallery>

[[Category: Geological regions of Scotland]]

[[Category:Geological regions of Scotland]]

Category:Grampian Highlands

2015-09-17T07:50:26Z

Lmo:

Many of the articles in this category are derived from the following BGS publications:
::[[British regional geology: Grampian Highlands|Grampian Highlands regional guide]]
::[[Cainozoic geology and landscape evolution of north-east Scotland. Memoir of the British Geological Survey, sheets 66E, 67, 76E, 77, 86E, 87W, 87E, 95, 96W, 96E and 97 (Scotland)|Cainozoic geology and landscape evolution of north-east Scotland]]

<gallery left mode=packed heights ="150px">

File:P749349.jpg|[[British regional geology: Grampian Highlands|Link]]
File:P915245.jpg|[[Cainozoic geology and landscape evolution of north-east Scotland. Memoir of the British Geological Survey, sheets 66E, 67, 76E, 77, 86E, 87W, 87E, 95, 96W, 96E and 97 (Scotland)|Link]]

</gallery>

[[Category: Geological regions of Scotland]]

[[Category:Geological regions of Scotland]]

Category:Grampian Highlands

2015-09-17T07:48:44Z

Lmo:

Many of the articles in this category are derived from the following BGS publications:
::[[British regional geology: Grampian Highlands|Grampian Highlands regional guide]],
::[[Cainozoic geology and landscape evolution of north-east Scotland. Memoir of the British Geological Survey, sheets 66E, 67, 76E, 77, 86E, 87W, 87E, 95, 96W, 96E and 97 (Scotland)|Cainozoic geology and landscape evolution of north-east Scotland]]

<gallery mode=packed heights ="150px">

File:P749349.jpg|[[British regional geology: Grampian Highlands|Link]]
File:P915245.jpg|[[Cainozoic geology and landscape evolution of north-east Scotland. Memoir of the British Geological Survey, sheets 66E, 67, 76E, 77, 86E, 87W, 87E, 95, 96W, 96E and 97 (Scotland)|Link]]

</gallery>

[[Category: Geological regions of Scotland]]

[[Category:Geological regions of Scotland]]

Cainozoic geology and landscape evolution of north-east Scotland - important localities

2015-09-16T12:22:49Z

Lmo:

Cainozoic of north-east Scotland, introduction

2015-09-16T11:01:29Z

Lmo:

Cainozoic of north-east Scotland, introduction

2015-09-16T11:00:40Z

Lmo:

Cainozoic of north-east Scotland, introduction

2015-09-16T10:57:58Z

Lmo: /* Introduction */

Results of shallow geophysical surveys, Cainozoic of north-east Scotland

2015-09-16T10:56:41Z

Lmo: /* Ground probing radar traverses */

'''From: Merritt, J W, Auton, C A, Connell, E R, Hall, A M, and Peacock, J D. 2003. [[Cainozoic geology and landscape evolution of north-east Scotland. Memoir of the British Geological Survey, sheets 66E, 67, 76E, 77, 86E, 87W, 87E, 95, 96W, 96E and 97 (Scotland)|Cainozoic geology and landscape evolution of north-east Scotland]]. Memoir of the British Geological Survey, sheets 66E, 67, 76E, 77, 86E, 87W, 87E, 95, 96W, 96E and 97 (Scotland).'''

= Results of shallow geophysical surveys =
During surveys of the Cainozoic deposits in north-east Scotland various shallow geophysical techniques have been used to provide data on the nature, thickness and lateral extent of concealed sedimentary units ([[Cainozoic geology and landscape evolution of north-east Scotland. Memoir of the British Geological Survey, sheets 66E, 67, 76E, 77, 86E, 87W, 87E, 95, 96W, 96E and 97 (Scotland)#Two Applied geology|Applied geology]]). Interpretation of electrical conductivity and resistivity measurements, in particular, has also provided insights into the lateral heterogeneity typical of the surface deposits of the district.

== Conductivity survey ==
[[File:P915334.png|left|thumbnail|Location of published sand and gravel resource assessment sheets and administrative areas in north-east Scotland. P915334.]]
[[File:P915337.png|thumbnail|Houff or Ury area. P915337.]]
The methods employed and the results from a conductivity survey in the vicinity of the Houff of Ury (NO 856 889), near Stonehaven, and the resistivity soundings from the Inverurie–Stonehaven sand and gravel assessment area (MAR 148 on [[Media:P915334.png|P915334]]), are fully described in Auton et al. (1988) and Auton (1992). Both techniques provided insights into the three dimensional distribution of workable deposits of sand and gravel, augmenting the surface mapping information. For example, interpretation of a contoured plot of ground conductivity values in the Houff of Ury area ([[Media:P915337.png|P915337]] a), in conjunction with detailed geological mapping, resulted in a 60 per cent reduction in the estimated extent of sand and gravel, compared with that recorded during the primary geological survey of the area in 1884. It also led to the recognition of minor, but notable amounts of workable sand and gravel ([[Media:P915337.png|P915337]] b) concealed beneath thin till overburden.

== Resistivity surveys ==
Forty three resistivity depth soundings were taken at 25 sites during the Inverurie–Stonehaven sand and gravel resource survey. The soundings, together with data obtained from 173 sample points (trial pits, exposures and boreholes) were used to characterise the Quaternary sequences in the area. Eight of the resistivity sites were positioned close to sample points to allow calibration of resistivity values. The calibrated results enhanced extrapolation of the nature and thickness of deposits between sample points, particularly in the major river valleys, where the full thickness of water saturated material was commonly not proved by pitting and shallow drilling.

[[File:P915338.png|thumbnail|Frequency distribution of interpreted resistivity values from the Banchory-Stonehaven area. P915338.]]
The soundings also provided data on the typical range of resistivities for each type of Quaternary deposit encountered [[Media:P915338.png|(P915338)]]. For example, resistivity values for ‘clayey’ materials, such as till and hummocky glacial deposits, were low, ranging from about 18 to 300 ohm m, whereas values for sand and gravel were high, ranging from 400 to 10 000 ohm m. The range of resistivity values obtained from 44 soundings taken in the adjacent Strachan-Auchenblae–Catterline assessment area (Auton et al., 1990) was somewhat larger. Values of 175 to 700 ohm m were obtained for tills, and 10 000 to 17 000 ohm m for sands and gravels of the East Grampian Drift Group in the Strachan area; values of 150 to 900 ohm m (till) and 300 to 6000 ohm m (sand and gravel) were recorded for deposits of the Mearns Drift Group, between Auchenblae and Catterline.

Differences between the ranges of values obtained from the two assessment areas were probably, in part, a reflection of moisture content, particularly in the permeable, sandy Quaternary strata, at the time of survey. The Inverurie–Stonehaven soundings were taken when the ground was wet, in early spring, whereas the Strachan–Auchenblae–Catterline soundings were made when the ground was dry, at the end of a notably dry summer. The resistivity values for tills of the East Grampian and Mearns drift groups are very similar in the Strachan–Auchenblae–Catterline area, and comparable to many of those recorded from tills in the Inverurie–Stonehaven area. The resistivity values from sands and gravels of the Mearns Drift Group are generally lower than those from the East Grampian Drift Group and probably reflect the finer grained and more silty nature of the former deposits.

The resistivity contrast between permeable sand and gravel, and less permeable deposits (till, glaciolacustrine silt and clay) was evident in both assessment surveys allowing clear subdivision of the Quaternary sequences, based on their geophysical signature. However, the contrast between Quaternary deposits and bedrock was generally less evident and in places accurate rockhead depth was difficult to determine without nearby borehole control. The resistivity values obtained for the Quaternary sediments in north-east Scotland are generally much higher than those in southern Britain (Auton, 1992). This reflects, in part, the crystalline or sandy nature of the resistant bedrock parent material, incorporated in the Quaternary deposits of the district, and also the high proportion of boulders and cobbles in the sediments. In southern England, in particular, much of the fine-grained material in glacigenic sediments is derived from mudstone bedrock and large clasts are normally less numerous.

== Ground probing radar traverses ==
The two ground probing radar (GPR) traverses (Greenwood and Raines, 1994), each about 750 m in length, were undertaken in the Houff of Ury area (sited on [[Media:P915337.png|P915337]] a). They provided data on the lateral extent and sedimentary architecture of the Quaternary deposits beyond what could be gleaned from surface mapping, conductivity measurements and the sinking of boreholes and trial pits (Greenwood et al., 1995). Gently inclined reflectors were interpreted as corresponding with large-scale foreset bedding typical of glaciofluvial deltaic deposits within the Drumlithie Sand and Gravel Formation in the area. These deltas form rounded and flat-topped mounds. Organised, quiet, layered patterns of reflectors, are thought to be typical of flat-lying glaciolacustrine deposits (Ury Silts Formation) infilling shallow ice-scoured rock basins. The glaciolacustrine sediments typically comprise silty, fine-grained sand and sandy silt. Multiple diffractions, typical of pebble and cobble gravel, were seen beneath topographic highs. These correspond to gravelly deltaic topset beds; the gently inclined reflectors indicating foreset bedding are developed on the flanks of the topographic highs. Lower amplitude diffraction patterns, indicating sediments containing scattered boulders and cobbles, were seen to be characteristic of till overlying Dalradian metamorphic bedrock.

[[File:P915339.png|left|thumbnail|Buchan Ridge. Location of GPR traverses and resistivity soundings and interpreted GPR profile. P915339.]]
Four GPR traverses ([[Media:P915339.png|P915339]] a) were made across the type area of the Buchan Ridge Gravel Member at Moss of Cruden, during 1994, to image the internal geometry of the deposit and the form of its basal contact with the underlying bedrock. A short traverse was also undertaken along a track through a forestry plantation at Moss of Auquharney (NJ 023 397), some 150 m south of the type area. The resulting profiles (Greenwood and Raines, 1994), together with data from trial pits, boreholes, and resistivity soundings provided important evidence bearing on the origin of the gravel ([[Palaeogene and Neogene deposits, Cainozoic of north-east Scotland|Palaeogene and Neogene deposits]]; Site 14 [[Moss of Cruden - locality, Cainozoic of north-east Scotland|Moss of Cruden]]).

The most informative GPR profile (line 1) is almost coincident with the pitting transect A1–A of Hall and Jarvis (1994, fig.3), across the northern slope of the ridge at Moss of Cruden. Part of the north-west to south-east profile, (162–364 m) is shown in [[Media:P915339.png|P915339]] b. The series of shallow-dipping, well-ordered reflections (without diffractions) indicates undisturbed Palaeogene to Neogene gravel (Buchan Ridge Gravel Member), with low-angle cross-stratification dipping towards the axis of the ridge. Farther up-slope (276–342 m), the GPR reflectors are distorted by diffractions that may indicate periglacial and glacitectonic disturbance of the upper part of the gravel. The profile shows the cross-stratified gravel unit thinning north-westwards, confirming that its feather edge rests on weathered Lower Cretaceous sandstone and Caledonian granitic bedrock.

The Cretaceous Moreseat Sandstone, which is largely decomposed to soft sandy silt and silty sand, is characterised by a diminution in radar reflectivity. This was only clearly imaged toward the north-western end of the profile (Greenwood et al.,1995, fig.5, 80–100 m). The resistivity depth probes and radar indicate that around 25 m of Buchan Ridge Gravel lies beneath the crest of the ridge, infilling a channel running parallel to the line of the ridge.

[[File:P915340.png|thumbnail|Buchan Ridge resistivity model. P915340.]]
Interpretation of resistivity data from Moss of Cruden has allowed modelling of resistivity values for parts of the sequence encountered in the GPR profile 1 [[Media:P915340.png|(P915340)]]. The topsoil is characterised by high resistivity values (2675–5940 ohm m) and the upper parts of the Buchan Ridge Gravel display a range of lower resistivities (447–2534 ohm m). This is thought to be due, in part, to variations in the proportions of kaolinised granitic clasts throughout the unit, the presence of interbeds of clayey pebbly sand (known from the upper part of the gravel sequence in Borehole NK 04 SW3) and the disturbance of bedding, indicated by distorted diffractions in the GPR profile. A layer, about 10 m thick, displaying relatively uniform low resistivities (307–355 ohm m) occurs below the ‘disturbed’ gravel at sounding sites MOSS and M1-285; it reaches the surface at M1-225. Its uniform resistivity response is taken to indicate that this gravel (with its shallow-dipping, well-ordered GPR reflections) is little disturbed and generally contains more kaolinitic material, in the form of decomposed granite cobbles and as fine-grained matrix, than the overlying ‘disturbed’ material. The absence of the latter in sounding M1-225, suggests that the upper ‘disturbed’ units are only well preserved where the gravel is thickest (towards the crest of the ridge); they have probably been removed on the flanks of the ridge by glacial erosion.

The presence of Moreseat Sandstone, infilling a topographic depression in deeply decomposed granite bedrock (between M1-225 and MOSS), is suggested by a 120 ohm m layer at the base of sounding M1-285 and corroborated by the trial pitting results reported by Hall and Jarvis (1994). A value of 120 ohm m is lower than might be expected for sandstone, but is comparable to values of 76–97 ohm m obtained for decomposed Devonian sandy siltstone from the Stonehaven–Auchenblae area (Auton et al., 1990). The very low resistivity (22 ohm m) layer from about 112 to 95 m above OD in sounding M-225, corresponds to grussified granitic bedrock recorded at the bottom of trial pit 15 in Hall and Jarvis (1994, fig.3). Similar (29.5 ohm m) deeply weathered material, some 23 m thick, overlies fresh granite bedrock (3640 ohm m) in sounding MOSS on the ridge crest.

Five GPR traverses were also made (in 1994) across the type area of the Windy Hills Gravel Member (Greenwood et al., 1995). The interpreted GPR data are incorporated in the description of the [[Windyhills - locality, Cainozoic of north-east Scotland|Windy Hills]] site (see also [[Palaeogene and Neogene deposits, Cainozoic of north-east Scotland|Palaeogene and Neogene deposits]]).

== References ==
[[References, Cainozoic of north-east Scotland|Full reference list]]

[[Category:Grampian Highlands]]

Results of shallow geophysical surveys, Cainozoic of north-east Scotland

2015-09-16T10:55:10Z

Lmo: /* Ground probing radar traverses */

'''From: Merritt, J W, Auton, C A, Connell, E R, Hall, A M, and Peacock, J D. 2003. [[Cainozoic geology and landscape evolution of north-east Scotland. Memoir of the British Geological Survey, sheets 66E, 67, 76E, 77, 86E, 87W, 87E, 95, 96W, 96E and 97 (Scotland)|Cainozoic geology and landscape evolution of north-east Scotland]]. Memoir of the British Geological Survey, sheets 66E, 67, 76E, 77, 86E, 87W, 87E, 95, 96W, 96E and 97 (Scotland).'''

= Results of shallow geophysical surveys =
During surveys of the Cainozoic deposits in north-east Scotland various shallow geophysical techniques have been used to provide data on the nature, thickness and lateral extent of concealed sedimentary units ([[Cainozoic geology and landscape evolution of north-east Scotland. Memoir of the British Geological Survey, sheets 66E, 67, 76E, 77, 86E, 87W, 87E, 95, 96W, 96E and 97 (Scotland)#Two Applied geology|Applied geology]]). Interpretation of electrical conductivity and resistivity measurements, in particular, has also provided insights into the lateral heterogeneity typical of the surface deposits of the district.

== Conductivity survey ==
[[File:P915334.png|left|thumbnail|Location of published sand and gravel resource assessment sheets and administrative areas in north-east Scotland. P915334.]]
[[File:P915337.png|thumbnail|Houff or Ury area. P915337.]]
The methods employed and the results from a conductivity survey in the vicinity of the Houff of Ury (NO 856 889), near Stonehaven, and the resistivity soundings from the Inverurie–Stonehaven sand and gravel assessment area (MAR 148 on [[Media:P915334.png|P915334]]), are fully described in Auton et al. (1988) and Auton (1992). Both techniques provided insights into the three dimensional distribution of workable deposits of sand and gravel, augmenting the surface mapping information. For example, interpretation of a contoured plot of ground conductivity values in the Houff of Ury area ([[Media:P915337.png|P915337]] a), in conjunction with detailed geological mapping, resulted in a 60 per cent reduction in the estimated extent of sand and gravel, compared with that recorded during the primary geological survey of the area in 1884. It also led to the recognition of minor, but notable amounts of workable sand and gravel ([[Media:P915337.png|P915337]] b) concealed beneath thin till overburden.

== Resistivity surveys ==
Forty three resistivity depth soundings were taken at 25 sites during the Inverurie–Stonehaven sand and gravel resource survey. The soundings, together with data obtained from 173 sample points (trial pits, exposures and boreholes) were used to characterise the Quaternary sequences in the area. Eight of the resistivity sites were positioned close to sample points to allow calibration of resistivity values. The calibrated results enhanced extrapolation of the nature and thickness of deposits between sample points, particularly in the major river valleys, where the full thickness of water saturated material was commonly not proved by pitting and shallow drilling.

[[File:P915338.png|thumbnail|Frequency distribution of interpreted resistivity values from the Banchory-Stonehaven area. P915338.]]
The soundings also provided data on the typical range of resistivities for each type of Quaternary deposit encountered [[Media:P915338.png|(P915338)]]. For example, resistivity values for ‘clayey’ materials, such as till and hummocky glacial deposits, were low, ranging from about 18 to 300 ohm m, whereas values for sand and gravel were high, ranging from 400 to 10 000 ohm m. The range of resistivity values obtained from 44 soundings taken in the adjacent Strachan-Auchenblae–Catterline assessment area (Auton et al., 1990) was somewhat larger. Values of 175 to 700 ohm m were obtained for tills, and 10 000 to 17 000 ohm m for sands and gravels of the East Grampian Drift Group in the Strachan area; values of 150 to 900 ohm m (till) and 300 to 6000 ohm m (sand and gravel) were recorded for deposits of the Mearns Drift Group, between Auchenblae and Catterline.

Differences between the ranges of values obtained from the two assessment areas were probably, in part, a reflection of moisture content, particularly in the permeable, sandy Quaternary strata, at the time of survey. The Inverurie–Stonehaven soundings were taken when the ground was wet, in early spring, whereas the Strachan–Auchenblae–Catterline soundings were made when the ground was dry, at the end of a notably dry summer. The resistivity values for tills of the East Grampian and Mearns drift groups are very similar in the Strachan–Auchenblae–Catterline area, and comparable to many of those recorded from tills in the Inverurie–Stonehaven area. The resistivity values from sands and gravels of the Mearns Drift Group are generally lower than those from the East Grampian Drift Group and probably reflect the finer grained and more silty nature of the former deposits.

The resistivity contrast between permeable sand and gravel, and less permeable deposits (till, glaciolacustrine silt and clay) was evident in both assessment surveys allowing clear subdivision of the Quaternary sequences, based on their geophysical signature. However, the contrast between Quaternary deposits and bedrock was generally less evident and in places accurate rockhead depth was difficult to determine without nearby borehole control. The resistivity values obtained for the Quaternary sediments in north-east Scotland are generally much higher than those in southern Britain (Auton, 1992). This reflects, in part, the crystalline or sandy nature of the resistant bedrock parent material, incorporated in the Quaternary deposits of the district, and also the high proportion of boulders and cobbles in the sediments. In southern England, in particular, much of the fine-grained material in glacigenic sediments is derived from mudstone bedrock and large clasts are normally less numerous.

== Ground probing radar traverses ==
The two ground probing radar (GPR) traverses (Greenwood and Raines, 1994), each about 750 m in length, were undertaken in the Houff of Ury area (sited on [[Media:P915337.png|P915337]] a). They provided data on the lateral extent and sedimentary architecture of the Quaternary deposits beyond what could be gleaned from surface mapping, conductivity measurements and the sinking of boreholes and trial pits (Greenwood et al., 1995). Gently inclined reflectors were interpreted as corresponding with large-scale foreset bedding typical of glaciofluvial deltaic deposits within the Drumlithie Sand and Gravel Formation in the area. These deltas form rounded and flat-topped mounds. Organised, quiet, layered patterns of reflectors, are thought to be typical of flat-lying glaciolacustrine deposits (Ury Silts Formation) infilling shallow ice-scoured rock basins. The glaciolacustrine sediments typically comprise silty, fine-grained sand and sandy silt. Multiple diffractions, typical of pebble and cobble gravel, were seen beneath topographic highs. These correspond to gravelly deltaic topset beds; the gently inclined reflectors indicating foreset bedding are developed on the flanks of the topographic highs. Lower amplitude diffraction patterns, indicating sediments containing scattered boulders and cobbles, were seen to be characteristic of till overlying Dalradian metamorphic bedrock.

[[File:P915339.png|thumbnail|Buchan Ridge. Location of GPR traverses and resistivity soundings and interpreted GPR profile. P915339.]]
Four GPR traverses ([[Media:P915339.png|P915339]] a) were made across the type area of the Buchan Ridge Gravel Member at Moss of Cruden, during 1994, to image the internal geometry of the deposit and the form of its basal contact with the underlying bedrock. A short traverse was also undertaken along a track through a forestry plantation at Moss of Auquharney (NJ 023 397), some 150 m south of the type area. The resulting profiles (Greenwood and Raines, 1994), together with data from trial pits, boreholes, and resistivity soundings provided important evidence bearing on the origin of the gravel ([[Palaeogene and Neogene deposits, Cainozoic of north-east Scotland|Palaeogene and Neogene deposits]]; Site 14 [[Moss of Cruden - locality, Cainozoic of north-east Scotland|Moss of Cruden]]).

The most informative GPR profile (line 1) is almost coincident with the pitting transect A1–A of Hall and Jarvis (1994, fig.3), across the northern slope of the ridge at Moss of Cruden. Part of the north-west to south-east profile, (162–364 m) is shown in [[Media:P915339.png|P915339]] b. The series of shallow-dipping, well-ordered reflections (without diffractions) indicates undisturbed Palaeogene to Neogene gravel (Buchan Ridge Gravel Member), with low-angle cross-stratification dipping towards the axis of the ridge. Farther up-slope (276–342 m), the GPR reflectors are distorted by diffractions that may indicate periglacial and glacitectonic disturbance of the upper part of the gravel. The profile shows the cross-stratified gravel unit thinning north-westwards, confirming that its feather edge rests on weathered Lower Cretaceous sandstone and Caledonian granitic bedrock.

The Cretaceous Moreseat Sandstone, which is largely decomposed to soft sandy silt and silty sand, is characterised by a diminution in radar reflectivity. This was only clearly imaged toward the north-western end of the profile (Greenwood et al.,1995, fig.5, 80–100 m). The resistivity depth probes and radar indicate that around 25 m of Buchan Ridge Gravel lies beneath the crest of the ridge, infilling a channel running parallel to the line of the ridge.

[[File:P915340.png|thumbnail|Buchan Ridge resistivity model. P915340.]]
Interpretation of resistivity data from Moss of Cruden has allowed modelling of resistivity values for parts of the sequence encountered in the GPR profile 1 [[Media:P915340.png|(P915340)]]. The topsoil is characterised by high resistivity values (2675–5940 ohm m) and the upper parts of the Buchan Ridge Gravel display a range of lower resistivities (447–2534 ohm m). This is thought to be due, in part, to variations in the proportions of kaolinised granitic clasts throughout the unit, the presence of interbeds of clayey pebbly sand (known from the upper part of the gravel sequence in Borehole NK 04 SW3) and the disturbance of bedding, indicated by distorted diffractions in the GPR profile. A layer, about 10 m thick, displaying relatively uniform low resistivities (307–355 ohm m) occurs below the ‘disturbed’ gravel at sounding sites MOSS and M1-285; it reaches the surface at M1-225. Its uniform resistivity response is taken to indicate that this gravel (with its shallow-dipping, well-ordered GPR reflections) is little disturbed and generally contains more kaolinitic material, in the form of decomposed granite cobbles and as fine-grained matrix, than the overlying ‘disturbed’ material. The absence of the latter in sounding M1-225, suggests that the upper ‘disturbed’ units are only well preserved where the gravel is thickest (towards the crest of the ridge); they have probably been removed on the flanks of the ridge by glacial erosion.

The presence of Moreseat Sandstone, infilling a topographic depression in deeply decomposed granite bedrock (between M1-225 and MOSS), is suggested by a 120 ohm m layer at the base of sounding M1-285 and corroborated by the trial pitting results reported by Hall and Jarvis (1994). A value of 120 ohm m is lower than might be expected for sandstone, but is comparable to values of 76–97 ohm m obtained for decomposed Devonian sandy siltstone from the Stonehaven–Auchenblae area (Auton et al., 1990). The very low resistivity (22 ohm m) layer from about 112 to 95 m above OD in sounding M-225, corresponds to grussified granitic bedrock recorded at the bottom of trial pit 15 in Hall and Jarvis (1994, fig.3). Similar (29.5 ohm m) deeply weathered material, some 23 m thick, overlies fresh granite bedrock (3640 ohm m) in sounding MOSS on the ridge crest.

Five GPR traverses were also made (in 1994) across the type area of the Windy Hills Gravel Member (Greenwood et al., 1995). The interpreted GPR data are incorporated in the description of the [[Windyhills - locality, Cainozoic of north-east Scotland|Windy Hills]] site (see also [[Palaeogene and Neogene deposits, Cainozoic of north-east Scotland|Palaeogene and Neogene deposits]]).

== References ==
[[References, Cainozoic of north-east Scotland|Full reference list]]

[[Category:Grampian Highlands]]

Results of shallow geophysical surveys, Cainozoic of north-east Scotland

2015-09-16T10:43:08Z

Lmo: /* Resistivity surveys */

'''From: Merritt, J W, Auton, C A, Connell, E R, Hall, A M, and Peacock, J D. 2003. [[Cainozoic geology and landscape evolution of north-east Scotland. Memoir of the British Geological Survey, sheets 66E, 67, 76E, 77, 86E, 87W, 87E, 95, 96W, 96E and 97 (Scotland)|Cainozoic geology and landscape evolution of north-east Scotland]]. Memoir of the British Geological Survey, sheets 66E, 67, 76E, 77, 86E, 87W, 87E, 95, 96W, 96E and 97 (Scotland).'''

= Results of shallow geophysical surveys =
During surveys of the Cainozoic deposits in north-east Scotland various shallow geophysical techniques have been used to provide data on the nature, thickness and lateral extent of concealed sedimentary units ([[Cainozoic geology and landscape evolution of north-east Scotland. Memoir of the British Geological Survey, sheets 66E, 67, 76E, 77, 86E, 87W, 87E, 95, 96W, 96E and 97 (Scotland)#Two Applied geology|Applied geology]]). Interpretation of electrical conductivity and resistivity measurements, in particular, has also provided insights into the lateral heterogeneity typical of the surface deposits of the district.

== Conductivity survey ==
[[File:P915334.png|left|thumbnail|Location of published sand and gravel resource assessment sheets and administrative areas in north-east Scotland. P915334.]]
[[File:P915337.png|thumbnail|Houff or Ury area. P915337.]]
The methods employed and the results from a conductivity survey in the vicinity of the Houff of Ury (NO 856 889), near Stonehaven, and the resistivity soundings from the Inverurie–Stonehaven sand and gravel assessment area (MAR 148 on [[Media:P915334.png|P915334]]), are fully described in Auton et al. (1988) and Auton (1992). Both techniques provided insights into the three dimensional distribution of workable deposits of sand and gravel, augmenting the surface mapping information. For example, interpretation of a contoured plot of ground conductivity values in the Houff of Ury area ([[Media:P915337.png|P915337]] a), in conjunction with detailed geological mapping, resulted in a 60 per cent reduction in the estimated extent of sand and gravel, compared with that recorded during the primary geological survey of the area in 1884. It also led to the recognition of minor, but notable amounts of workable sand and gravel ([[Media:P915337.png|P915337]] b) concealed beneath thin till overburden.

== Resistivity surveys ==
Forty three resistivity depth soundings were taken at 25 sites during the Inverurie–Stonehaven sand and gravel resource survey. The soundings, together with data obtained from 173 sample points (trial pits, exposures and boreholes) were used to characterise the Quaternary sequences in the area. Eight of the resistivity sites were positioned close to sample points to allow calibration of resistivity values. The calibrated results enhanced extrapolation of the nature and thickness of deposits between sample points, particularly in the major river valleys, where the full thickness of water saturated material was commonly not proved by pitting and shallow drilling.

[[File:P915338.png|thumbnail|Frequency distribution of interpreted resistivity values from the Banchory-Stonehaven area. P915338.]]
The soundings also provided data on the typical range of resistivities for each type of Quaternary deposit encountered [[Media:P915338.png|(P915338)]]. For example, resistivity values for ‘clayey’ materials, such as till and hummocky glacial deposits, were low, ranging from about 18 to 300 ohm m, whereas values for sand and gravel were high, ranging from 400 to 10 000 ohm m. The range of resistivity values obtained from 44 soundings taken in the adjacent Strachan-Auchenblae–Catterline assessment area (Auton et al., 1990) was somewhat larger. Values of 175 to 700 ohm m were obtained for tills, and 10 000 to 17 000 ohm m for sands and gravels of the East Grampian Drift Group in the Strachan area; values of 150 to 900 ohm m (till) and 300 to 6000 ohm m (sand and gravel) were recorded for deposits of the Mearns Drift Group, between Auchenblae and Catterline.

Differences between the ranges of values obtained from the two assessment areas were probably, in part, a reflection of moisture content, particularly in the permeable, sandy Quaternary strata, at the time of survey. The Inverurie–Stonehaven soundings were taken when the ground was wet, in early spring, whereas the Strachan–Auchenblae–Catterline soundings were made when the ground was dry, at the end of a notably dry summer. The resistivity values for tills of the East Grampian and Mearns drift groups are very similar in the Strachan–Auchenblae–Catterline area, and comparable to many of those recorded from tills in the Inverurie–Stonehaven area. The resistivity values from sands and gravels of the Mearns Drift Group are generally lower than those from the East Grampian Drift Group and probably reflect the finer grained and more silty nature of the former deposits.

The resistivity contrast between permeable sand and gravel, and less permeable deposits (till, glaciolacustrine silt and clay) was evident in both assessment surveys allowing clear subdivision of the Quaternary sequences, based on their geophysical signature. However, the contrast between Quaternary deposits and bedrock was generally less evident and in places accurate rockhead depth was difficult to determine without nearby borehole control. The resistivity values obtained for the Quaternary sediments in north-east Scotland are generally much higher than those in southern Britain (Auton, 1992). This reflects, in part, the crystalline or sandy nature of the resistant bedrock parent material, incorporated in the Quaternary deposits of the district, and also the high proportion of boulders and cobbles in the sediments. In southern England, in particular, much of the fine-grained material in glacigenic sediments is derived from mudstone bedrock and large clasts are normally less numerous.

== Ground probing radar traverses ==
The two ground probing radar (GPR) traverses (Greenwood and Raines, 1994), each about 750 m in length, were undertaken in the Houff of Ury area (sited on P915337 a). They provided data on the lateral extent and sedimentary architecture of the Quaternary deposits beyond what could be gleaned from surface mapping, conductivity measurements and the sinking of boreholes and trial pits (Greenwood et al., 1995). Gently inclined reflectors were interpreted as corresponding with large-scale foreset bedding typical of glaciofluvial deltaic deposits within the Drumlithie Sand and Gravel Formation in the area. These deltas form rounded and flat-topped mounds. Organised, quiet, layered patterns of reflectors, are thought to be typical of flat-lying glaciolacustrine deposits (Ury Silts Formation) infilling shallow ice-scoured rock basins. The glaciolacustrine sediments typically comprise silty, fine-grained sand and sandy silt. Multiple diffractions, typical of pebble and cobble gravel, were seen beneath topographic highs. These correspond to gravelly deltaic topset beds; the gently inclined reflectors indicating foreset bedding are developed on the flanks of the topographic highs. Lower amplitude diffraction patterns, indicating sediments containing scattered boulders and cobbles, were seen to be characteristic of till overlying Dalradian metamorphic bedrock.

Four GPR traverses (P915339 a) were made across the type area of the Buchan Ridge Gravel Member at Moss of Cruden, during 1994, to image the internal geometry of the deposit and the form of its basal contact with the underlying bedrock. A short traverse was also undertaken along a track through a forestry plantation at Moss of Auquharney (NJ 023 397), some 150 m south of the type area. The resulting profiles (Greenwood and Raines, 1994), together with data from trial pits, boreholes, and resistivity soundings provided important evidence bearing on the origin of the gravel (Chapter 4; Appendix 1Site 14).

The most informative GPR profile (line 1) is almost coincident with the pitting transect A1–A of Hall and Jarvis (1994, fig.3), across the northern slope of the ridge at Moss of Cruden. Part of the north-west to south-east profile, (162–364 m) is shown in P915339 b. The series of shallow-dipping, well-ordered reflections (without diffractions) indicates undisturbed Palaeogene to Neogene gravel (Buchan Ridge Gravel Member), with low-angle cross-stratification dipping towards the axis of the ridge. Farther up-slope (276–342 m), the GPR reflectors are distorted by diffractions that may indicate periglacial and glacitectonic disturbance of the upper part of the gravel. The profile shows the cross-stratified gravel unit thinning north-westwards, confirming that its feather edge rests on weathered Lower Cretaceous sandstone and Caledonian granitic bedrock.

The Cretaceous Moreseat Sandstone, which is largely decomposed to soft sandy silt and silty sand, is characterised by a diminution in radar reflectivity. This was only clearly imaged toward the north-western end of the profile (Greenwood et al.,1995, fig.5, 80–100 m). The resistivity depth probes and radar indicate that around 25 m of Buchan Ridge Gravel lies beneath the crest of the ridge, infilling a channel running parallel to the line of the ridge.

Interpretation of resistivity data from Moss of Cruden has allowed modelling of resistivity values for parts of the sequence encountered in the GPR profile 1 (P915340). The topsoil is characterised by high resistivity values (2675–5940 ohm m) and the upper parts of the Buchan Ridge Gravel display a range of lower resistivities (447–2534 ohm m). This is thought to be due, in part, to variations in the proportions of kaolinised granitic clasts throughout the unit, the presence of interbeds of clayey pebbly sand (known from the upper part of the gravel sequence in Borehole NK 04 SW3) and the disturbance of bedding, indicated by distorted diffractions in the GPR profile. A layer, about 10 m thick, displaying relatively uniform low resistivities (307–355 ohm m) occurs below the ‘disturbed’ gravel at sounding sites MOSS and M1-285; it reaches the surface at M1-225. Its uniform resistivity response is taken to indicate that this gravel (with its shallow-dipping, well-ordered GPR reflections) is little disturbed and generally contains more kaolinitic material, in the form of decomposed granite cobbles and as fine-grained matrix, than the overlying ‘disturbed’ material. The absence of the latter in sounding M1-225, suggests that the upper ‘disturbed’ units are only well preserved where the gravel is thickest (towards the crest of the ridge); they have probably been removed on the flanks of the ridge by glacial erosion.

The presence of Moreseat Sandstone, infilling a topographic depression in deeply decomposed granite bedrock (between M1-225 and MOSS), is suggested by a 120 ohm m layer at the base of sounding M1-285 and corroborated by the trial pitting results reported by Hall and Jarvis (1994). A value of 120 ohm m is lower than might be expected for sandstone, but is comparable to values of 76–97 ohm m obtained for decomposed Devonian sandy siltstone from the Stonehaven–Auchenblae area (Auton et al., 1990). The very low resistivity (22 ohm m) layer from about 112 to 95 m above OD in sounding M-225, corresponds to grussified granitic bedrock recorded at the bottom of trial pit 15 in Hall and Jarvis (1994, fig.3). Similar (29.5 ohm m) deeply weathered material, some 23 m thick, overlies fresh granite bedrock (3640 ohm m) in sounding MOSS on the ridge crest.

Five GPR traverses were also made (in 1994) across the type area of the Windy Hills Gravel Member (Greenwood et al., 1995). The interpreted GPR data are incorporated in the description of the Windy Hills site given in Appendix 1 (see also Chapter 4).

== References ==
[[References, Cainozoic of north-east Scotland|Full reference list]]

[[Category:Grampian Highlands]]

Results of shallow geophysical surveys, Cainozoic of north-east Scotland

2015-09-16T10:42:05Z

Lmo: /* Conductivity survey */

'''From: Merritt, J W, Auton, C A, Connell, E R, Hall, A M, and Peacock, J D. 2003. [[Cainozoic geology and landscape evolution of north-east Scotland. Memoir of the British Geological Survey, sheets 66E, 67, 76E, 77, 86E, 87W, 87E, 95, 96W, 96E and 97 (Scotland)|Cainozoic geology and landscape evolution of north-east Scotland]]. Memoir of the British Geological Survey, sheets 66E, 67, 76E, 77, 86E, 87W, 87E, 95, 96W, 96E and 97 (Scotland).'''

= Results of shallow geophysical surveys =
During surveys of the Cainozoic deposits in north-east Scotland various shallow geophysical techniques have been used to provide data on the nature, thickness and lateral extent of concealed sedimentary units ([[Cainozoic geology and landscape evolution of north-east Scotland. Memoir of the British Geological Survey, sheets 66E, 67, 76E, 77, 86E, 87W, 87E, 95, 96W, 96E and 97 (Scotland)#Two Applied geology|Applied geology]]). Interpretation of electrical conductivity and resistivity measurements, in particular, has also provided insights into the lateral heterogeneity typical of the surface deposits of the district.

== Conductivity survey ==
[[File:P915334.png|left|thumbnail|Location of published sand and gravel resource assessment sheets and administrative areas in north-east Scotland. P915334.]]
[[File:P915337.png|thumbnail|Houff or Ury area. P915337.]]
The methods employed and the results from a conductivity survey in the vicinity of the Houff of Ury (NO 856 889), near Stonehaven, and the resistivity soundings from the Inverurie–Stonehaven sand and gravel assessment area (MAR 148 on [[Media:P915334.png|P915334]]), are fully described in Auton et al. (1988) and Auton (1992). Both techniques provided insights into the three dimensional distribution of workable deposits of sand and gravel, augmenting the surface mapping information. For example, interpretation of a contoured plot of ground conductivity values in the Houff of Ury area ([[Media:P915337.png|P915337]] a), in conjunction with detailed geological mapping, resulted in a 60 per cent reduction in the estimated extent of sand and gravel, compared with that recorded during the primary geological survey of the area in 1884. It also led to the recognition of minor, but notable amounts of workable sand and gravel ([[Media:P915337.png|P915337]] b) concealed beneath thin till overburden.

== Resistivity surveys ==
Forty three resistivity depth soundings were taken at 25 sites during the Inverurie–Stonehaven sand and gravel resource survey. The soundings, together with data obtained from 173 sample points (trial pits, exposures and boreholes) were used to characterise the Quaternary sequences in the area. Eight of the resistivity sites were positioned close to sample points to allow calibration of resistivity values. The calibrated results enhanced extrapolation of the nature and thickness of deposits between sample points, particularly in the major river valleys, where the full thickness of water saturated material was commonly not proved by pitting and shallow drilling.

The soundings also provided data on the typical range of resistivities for each type of Quaternary deposit encountered (P915338). For example, resistivity values for ‘clayey’ materials, such as till and hummocky glacial deposits, were low, ranging from about 18 to 300 ohm m, whereas values for sand and gravel were high, ranging from 400 to 10 000 ohm m. The range of resistivity values obtained from 44 soundings taken in the adjacent Strachan-Auchenblae–Catterline assessment area (Auton et al., 1990) was somewhat larger. Values of 175 to 700 ohm m were obtained for tills, and 10 000 to 17 000 ohm m for sands and gravels of the East Grampian Drift Group in the Strachan area; values of 150 to 900 ohm m (till) and 300 to 6000 ohm m (sand and gravel) were recorded for deposits of the Mearns Drift Group, between Auchenblae and Catterline.

Differences between the ranges of values obtained from the two assessment areas were probably, in part, a reflection of moisture content, particularly in the permeable, sandy Quaternary strata, at the time of survey. The Inverurie–Stonehaven soundings were taken when the ground was wet, in early spring, whereas the Strachan–Auchenblae–Catterline soundings were made when the ground was dry, at the end of a notably dry summer. The resistivity values for tills of the East Grampian and Mearns drift groups are very similar in the Strachan–Auchenblae–Catterline area, and comparable to many of those recorded from tills in the Inverurie–Stonehaven area. The resistivity values from sands and gravels of the Mearns Drift Group are generally lower than those from the East Grampian Drift Group and probably reflect the finer grained and more silty nature of the former deposits.

The resistivity contrast between permeable sand and gravel, and less permeable deposits (till, glaciolacustrine silt and clay) was evident in both assessment surveys allowing clear subdivision of the Quaternary sequences, based on their geophysical signature. However, the contrast between Quaternary deposits and bedrock was generally less evident and in places accurate rockhead depth was difficult to determine without nearby borehole control. The resistivity values obtained for the Quaternary sediments in north-east Scotland are generally much higher than those in southern Britain (Auton, 1992). This reflects, in part, the crystalline or sandy nature of the resistant bedrock parent material, incorporated in the Quaternary deposits of the district, and also the high proportion of boulders and cobbles in the sediments. In southern England, in particular, much of the fine-grained material in glacigenic sediments is derived from mudstone bedrock and large clasts are normally less numerous.

== Ground probing radar traverses ==
The two ground probing radar (GPR) traverses (Greenwood and Raines, 1994), each about 750 m in length, were undertaken in the Houff of Ury area (sited on P915337 a). They provided data on the lateral extent and sedimentary architecture of the Quaternary deposits beyond what could be gleaned from surface mapping, conductivity measurements and the sinking of boreholes and trial pits (Greenwood et al., 1995). Gently inclined reflectors were interpreted as corresponding with large-scale foreset bedding typical of glaciofluvial deltaic deposits within the Drumlithie Sand and Gravel Formation in the area. These deltas form rounded and flat-topped mounds. Organised, quiet, layered patterns of reflectors, are thought to be typical of flat-lying glaciolacustrine deposits (Ury Silts Formation) infilling shallow ice-scoured rock basins. The glaciolacustrine sediments typically comprise silty, fine-grained sand and sandy silt. Multiple diffractions, typical of pebble and cobble gravel, were seen beneath topographic highs. These correspond to gravelly deltaic topset beds; the gently inclined reflectors indicating foreset bedding are developed on the flanks of the topographic highs. Lower amplitude diffraction patterns, indicating sediments containing scattered boulders and cobbles, were seen to be characteristic of till overlying Dalradian metamorphic bedrock.

Four GPR traverses (P915339 a) were made across the type area of the Buchan Ridge Gravel Member at Moss of Cruden, during 1994, to image the internal geometry of the deposit and the form of its basal contact with the underlying bedrock. A short traverse was also undertaken along a track through a forestry plantation at Moss of Auquharney (NJ 023 397), some 150 m south of the type area. The resulting profiles (Greenwood and Raines, 1994), together with data from trial pits, boreholes, and resistivity soundings provided important evidence bearing on the origin of the gravel (Chapter 4; Appendix 1Site 14).

The most informative GPR profile (line 1) is almost coincident with the pitting transect A1–A of Hall and Jarvis (1994, fig.3), across the northern slope of the ridge at Moss of Cruden. Part of the north-west to south-east profile, (162–364 m) is shown in P915339 b. The series of shallow-dipping, well-ordered reflections (without diffractions) indicates undisturbed Palaeogene to Neogene gravel (Buchan Ridge Gravel Member), with low-angle cross-stratification dipping towards the axis of the ridge. Farther up-slope (276–342 m), the GPR reflectors are distorted by diffractions that may indicate periglacial and glacitectonic disturbance of the upper part of the gravel. The profile shows the cross-stratified gravel unit thinning north-westwards, confirming that its feather edge rests on weathered Lower Cretaceous sandstone and Caledonian granitic bedrock.

The Cretaceous Moreseat Sandstone, which is largely decomposed to soft sandy silt and silty sand, is characterised by a diminution in radar reflectivity. This was only clearly imaged toward the north-western end of the profile (Greenwood et al.,1995, fig.5, 80–100 m). The resistivity depth probes and radar indicate that around 25 m of Buchan Ridge Gravel lies beneath the crest of the ridge, infilling a channel running parallel to the line of the ridge.

Interpretation of resistivity data from Moss of Cruden has allowed modelling of resistivity values for parts of the sequence encountered in the GPR profile 1 (P915340). The topsoil is characterised by high resistivity values (2675–5940 ohm m) and the upper parts of the Buchan Ridge Gravel display a range of lower resistivities (447–2534 ohm m). This is thought to be due, in part, to variations in the proportions of kaolinised granitic clasts throughout the unit, the presence of interbeds of clayey pebbly sand (known from the upper part of the gravel sequence in Borehole NK 04 SW3) and the disturbance of bedding, indicated by distorted diffractions in the GPR profile. A layer, about 10 m thick, displaying relatively uniform low resistivities (307–355 ohm m) occurs below the ‘disturbed’ gravel at sounding sites MOSS and M1-285; it reaches the surface at M1-225. Its uniform resistivity response is taken to indicate that this gravel (with its shallow-dipping, well-ordered GPR reflections) is little disturbed and generally contains more kaolinitic material, in the form of decomposed granite cobbles and as fine-grained matrix, than the overlying ‘disturbed’ material. The absence of the latter in sounding M1-225, suggests that the upper ‘disturbed’ units are only well preserved where the gravel is thickest (towards the crest of the ridge); they have probably been removed on the flanks of the ridge by glacial erosion.

The presence of Moreseat Sandstone, infilling a topographic depression in deeply decomposed granite bedrock (between M1-225 and MOSS), is suggested by a 120 ohm m layer at the base of sounding M1-285 and corroborated by the trial pitting results reported by Hall and Jarvis (1994). A value of 120 ohm m is lower than might be expected for sandstone, but is comparable to values of 76–97 ohm m obtained for decomposed Devonian sandy siltstone from the Stonehaven–Auchenblae area (Auton et al., 1990). The very low resistivity (22 ohm m) layer from about 112 to 95 m above OD in sounding M-225, corresponds to grussified granitic bedrock recorded at the bottom of trial pit 15 in Hall and Jarvis (1994, fig.3). Similar (29.5 ohm m) deeply weathered material, some 23 m thick, overlies fresh granite bedrock (3640 ohm m) in sounding MOSS on the ridge crest.

Five GPR traverses were also made (in 1994) across the type area of the Windy Hills Gravel Member (Greenwood et al., 1995). The interpreted GPR data are incorporated in the description of the Windy Hills site given in Appendix 1 (see also Chapter 4).

== References ==
[[References, Cainozoic of north-east Scotland|Full reference list]]

[[Category:Grampian Highlands]]

Results of shallow geophysical surveys, Cainozoic of north-east Scotland

2015-09-16T10:39:06Z

Lmo: /* Results of shallow geophysical surveys */

'''From: Merritt, J W, Auton, C A, Connell, E R, Hall, A M, and Peacock, J D. 2003. [[Cainozoic geology and landscape evolution of north-east Scotland. Memoir of the British Geological Survey, sheets 66E, 67, 76E, 77, 86E, 87W, 87E, 95, 96W, 96E and 97 (Scotland)|Cainozoic geology and landscape evolution of north-east Scotland]]. Memoir of the British Geological Survey, sheets 66E, 67, 76E, 77, 86E, 87W, 87E, 95, 96W, 96E and 97 (Scotland).'''

= Results of shallow geophysical surveys =
During surveys of the Cainozoic deposits in north-east Scotland various shallow geophysical techniques have been used to provide data on the nature, thickness and lateral extent of concealed sedimentary units ([[Cainozoic geology and landscape evolution of north-east Scotland. Memoir of the British Geological Survey, sheets 66E, 67, 76E, 77, 86E, 87W, 87E, 95, 96W, 96E and 97 (Scotland)#Two Applied geology|Applied geology]]). Interpretation of electrical conductivity and resistivity measurements, in particular, has also provided insights into the lateral heterogeneity typical of the surface deposits of the district.

== Conductivity survey ==
The methods employed and the results from a conductivity survey in the vicinity of the Houff of Ury (NO 856 889), near Stonehaven, and the resistivity soundings from the Inverurie–Stonehaven sand and gravel assessment area (MAR 148 on P915334), are fully described in Auton et al. (1988) and Auton (1992). Both techniques provided insights into the three dimensional distribution of workable deposits of sand and gravel, augmenting the surface mapping information. For example, interpretation of a contoured plot of ground conductivity values in the Houff of Ury area (P915337 a), in conjunction with detailed geological mapping, resulted in a 60 per cent reduction in the estimated extent of sand and gravel, compared with that recorded during the primary geological survey of the area in 1884. It also led to the recognition of minor, but notable amounts of workable sand and gravel (P915337 b) concealed beneath thin till overburden.

== Resistivity surveys ==
Forty three resistivity depth soundings were taken at 25 sites during the Inverurie–Stonehaven sand and gravel resource survey. The soundings, together with data obtained from 173 sample points (trial pits, exposures and boreholes) were used to characterise the Quaternary sequences in the area. Eight of the resistivity sites were positioned close to sample points to allow calibration of resistivity values. The calibrated results enhanced extrapolation of the nature and thickness of deposits between sample points, particularly in the major river valleys, where the full thickness of water saturated material was commonly not proved by pitting and shallow drilling.

The soundings also provided data on the typical range of resistivities for each type of Quaternary deposit encountered (P915338). For example, resistivity values for ‘clayey’ materials, such as till and hummocky glacial deposits, were low, ranging from about 18 to 300 ohm m, whereas values for sand and gravel were high, ranging from 400 to 10 000 ohm m. The range of resistivity values obtained from 44 soundings taken in the adjacent Strachan-Auchenblae–Catterline assessment area (Auton et al., 1990) was somewhat larger. Values of 175 to 700 ohm m were obtained for tills, and 10 000 to 17 000 ohm m for sands and gravels of the East Grampian Drift Group in the Strachan area; values of 150 to 900 ohm m (till) and 300 to 6000 ohm m (sand and gravel) were recorded for deposits of the Mearns Drift Group, between Auchenblae and Catterline.

Differences between the ranges of values obtained from the two assessment areas were probably, in part, a reflection of moisture content, particularly in the permeable, sandy Quaternary strata, at the time of survey. The Inverurie–Stonehaven soundings were taken when the ground was wet, in early spring, whereas the Strachan–Auchenblae–Catterline soundings were made when the ground was dry, at the end of a notably dry summer. The resistivity values for tills of the East Grampian and Mearns drift groups are very similar in the Strachan–Auchenblae–Catterline area, and comparable to many of those recorded from tills in the Inverurie–Stonehaven area. The resistivity values from sands and gravels of the Mearns Drift Group are generally lower than those from the East Grampian Drift Group and probably reflect the finer grained and more silty nature of the former deposits.

The resistivity contrast between permeable sand and gravel, and less permeable deposits (till, glaciolacustrine silt and clay) was evident in both assessment surveys allowing clear subdivision of the Quaternary sequences, based on their geophysical signature. However, the contrast between Quaternary deposits and bedrock was generally less evident and in places accurate rockhead depth was difficult to determine without nearby borehole control. The resistivity values obtained for the Quaternary sediments in north-east Scotland are generally much higher than those in southern Britain (Auton, 1992). This reflects, in part, the crystalline or sandy nature of the resistant bedrock parent material, incorporated in the Quaternary deposits of the district, and also the high proportion of boulders and cobbles in the sediments. In southern England, in particular, much of the fine-grained material in glacigenic sediments is derived from mudstone bedrock and large clasts are normally less numerous.

== Ground probing radar traverses ==
The two ground probing radar (GPR) traverses (Greenwood and Raines, 1994), each about 750 m in length, were undertaken in the Houff of Ury area (sited on P915337 a). They provided data on the lateral extent and sedimentary architecture of the Quaternary deposits beyond what could be gleaned from surface mapping, conductivity measurements and the sinking of boreholes and trial pits (Greenwood et al., 1995). Gently inclined reflectors were interpreted as corresponding with large-scale foreset bedding typical of glaciofluvial deltaic deposits within the Drumlithie Sand and Gravel Formation in the area. These deltas form rounded and flat-topped mounds. Organised, quiet, layered patterns of reflectors, are thought to be typical of flat-lying glaciolacustrine deposits (Ury Silts Formation) infilling shallow ice-scoured rock basins. The glaciolacustrine sediments typically comprise silty, fine-grained sand and sandy silt. Multiple diffractions, typical of pebble and cobble gravel, were seen beneath topographic highs. These correspond to gravelly deltaic topset beds; the gently inclined reflectors indicating foreset bedding are developed on the flanks of the topographic highs. Lower amplitude diffraction patterns, indicating sediments containing scattered boulders and cobbles, were seen to be characteristic of till overlying Dalradian metamorphic bedrock.

Four GPR traverses (P915339 a) were made across the type area of the Buchan Ridge Gravel Member at Moss of Cruden, during 1994, to image the internal geometry of the deposit and the form of its basal contact with the underlying bedrock. A short traverse was also undertaken along a track through a forestry plantation at Moss of Auquharney (NJ 023 397), some 150 m south of the type area. The resulting profiles (Greenwood and Raines, 1994), together with data from trial pits, boreholes, and resistivity soundings provided important evidence bearing on the origin of the gravel (Chapter 4; Appendix 1Site 14).

The most informative GPR profile (line 1) is almost coincident with the pitting transect A1–A of Hall and Jarvis (1994, fig.3), across the northern slope of the ridge at Moss of Cruden. Part of the north-west to south-east profile, (162–364 m) is shown in P915339 b. The series of shallow-dipping, well-ordered reflections (without diffractions) indicates undisturbed Palaeogene to Neogene gravel (Buchan Ridge Gravel Member), with low-angle cross-stratification dipping towards the axis of the ridge. Farther up-slope (276–342 m), the GPR reflectors are distorted by diffractions that may indicate periglacial and glacitectonic disturbance of the upper part of the gravel. The profile shows the cross-stratified gravel unit thinning north-westwards, confirming that its feather edge rests on weathered Lower Cretaceous sandstone and Caledonian granitic bedrock.

The Cretaceous Moreseat Sandstone, which is largely decomposed to soft sandy silt and silty sand, is characterised by a diminution in radar reflectivity. This was only clearly imaged toward the north-western end of the profile (Greenwood et al.,1995, fig.5, 80–100 m). The resistivity depth probes and radar indicate that around 25 m of Buchan Ridge Gravel lies beneath the crest of the ridge, infilling a channel running parallel to the line of the ridge.

Interpretation of resistivity data from Moss of Cruden has allowed modelling of resistivity values for parts of the sequence encountered in the GPR profile 1 (P915340). The topsoil is characterised by high resistivity values (2675–5940 ohm m) and the upper parts of the Buchan Ridge Gravel display a range of lower resistivities (447–2534 ohm m). This is thought to be due, in part, to variations in the proportions of kaolinised granitic clasts throughout the unit, the presence of interbeds of clayey pebbly sand (known from the upper part of the gravel sequence in Borehole NK 04 SW3) and the disturbance of bedding, indicated by distorted diffractions in the GPR profile. A layer, about 10 m thick, displaying relatively uniform low resistivities (307–355 ohm m) occurs below the ‘disturbed’ gravel at sounding sites MOSS and M1-285; it reaches the surface at M1-225. Its uniform resistivity response is taken to indicate that this gravel (with its shallow-dipping, well-ordered GPR reflections) is little disturbed and generally contains more kaolinitic material, in the form of decomposed granite cobbles and as fine-grained matrix, than the overlying ‘disturbed’ material. The absence of the latter in sounding M1-225, suggests that the upper ‘disturbed’ units are only well preserved where the gravel is thickest (towards the crest of the ridge); they have probably been removed on the flanks of the ridge by glacial erosion.

The presence of Moreseat Sandstone, infilling a topographic depression in deeply decomposed granite bedrock (between M1-225 and MOSS), is suggested by a 120 ohm m layer at the base of sounding M1-285 and corroborated by the trial pitting results reported by Hall and Jarvis (1994). A value of 120 ohm m is lower than might be expected for sandstone, but is comparable to values of 76–97 ohm m obtained for decomposed Devonian sandy siltstone from the Stonehaven–Auchenblae area (Auton et al., 1990). The very low resistivity (22 ohm m) layer from about 112 to 95 m above OD in sounding M-225, corresponds to grussified granitic bedrock recorded at the bottom of trial pit 15 in Hall and Jarvis (1994, fig.3). Similar (29.5 ohm m) deeply weathered material, some 23 m thick, overlies fresh granite bedrock (3640 ohm m) in sounding MOSS on the ridge crest.

Five GPR traverses were also made (in 1994) across the type area of the Windy Hills Gravel Member (Greenwood et al., 1995). The interpreted GPR data are incorporated in the description of the Windy Hills site given in Appendix 1 (see also Chapter 4).

== References ==
[[References, Cainozoic of north-east Scotland|Full reference list]]

[[Category:Grampian Highlands]]

Sand and gravel resources, Sheet 67 Stonehaven, Cainozoic of north-east Scotland

2015-09-16T10:32:30Z

Lmo:

Sand and gravel resources, Sheet 66E Banchory, Cainozoic of north-east Scotland

2015-09-16T10:29:04Z

Lmo:

'''From: Merritt, J W, Auton, C A, Connell, E R, Hall, A M, and Peacock, J D. 2003. [[Cainozoic geology and landscape evolution of north-east Scotland. Memoir of the British Geological Survey, sheets 66E, 67, 76E, 77, 86E, 87W, 87E, 95, 96W, 96E and 97 (Scotland)|Cainozoic geology and landscape evolution of north-east Scotland]]. Memoir of the British Geological Survey, sheets 66E, 67, 76E, 77, 86E, 87W, 87E, 95, 96W, 96E and 97 (Scotland).'''
__FORCETOC__
= Sheet 66E Banchory =
[[File:P915380.png|thumbnail|Glacial and glaciofluvial features and the distribution of glacigenic deposits on Sheet 66E Banchory. P915380.]]
The principal resources of the northern part of Sheet 66E [[Media:P915380.png|(P915380)]] occur within glaciofluvial and alluvial deposits in the valleys of the River Dee, Burn of Sheeoch and Burn of Canny. Extensive spreads of sand and gravel are also present in the valley of the Water of Feugh, in the vicinity of Strachan. Minor resources occur within terraced alluvial deposits and moundy glaciofluvial deposits in Glen Dye and as flat-lying spreads of sand, in a small lake basin near Lochhead of Leys (NO 695 979) and in a larger basin around Loch of Park (NJ 770 990).

Some potentially workable coarse aggregate, mixed with bouldery diamicton, is present within the moundy glacial deposits forming moraines to the north and east of Loch of Park. Similar morainic sediments also occur in the valleys of the Water of Aven, the Burn of Melmannoch, the Burn of Knock, and on the southern side of the valley of the Water of Feugh, in the vicinity of Powlair (NO 620 912). All are potential sources of low-grade aggregate. Discrete areas of deeply decomposed granitic bedrock, around Loch of Park, Powlair and the upper reaches of Garrol Burn also constitute sources of aggregate suitable for use as fill and road base.

In the southern part of Sheet 66E, the main spreads of sand and gravel form moundy topography on the northern margin of Strathmore, notably between Auchenblae and Drumlithie, and around Fettercairn. Less attractive deposits are present beneath the floodplains of the Bervie Water, Luther Water, Black Burn, Devilly Burn and Burn of Cauldcots, as well as in the discontinuous terraced spreads on the sides of the valleys. Deeply weathered exposures of Lower Devonian conglomerate north of the Glen of Drumtochty, constitute a resource of cobbly gravel which, in places, exceeds 3 m in thickness.

The sand and gravel resources in the Dee valley, downstream of Banchory and within the valley of the Burn of Sheeoch, were evaluated as part of Mineral Assessment Report 148. Those in the vicinity of Strachan and in Strathmore were included in MAR 149. The sands and gravels that crop out in the south-west corner of Sheet 66E have not been assessed in detail. They are described in Carroll (1995d).

The kettled terraces that flank the Dee, between Banchory and the eastern margin of Sheet 66E, contain extensive resources of well stratified gravel and sand, lying above the water table; they average 7.4 m in thickness. Gravelly deposits, beneath negligible overburden are also present underlying the floodplain; they average 10.4 m in thickness. The terraced glaciofluvial gravels have been worked to a depth of greater than 10 m in Park Quarry, near Gallow Hill (NO 806 978), where they merge into mounds and ridges of ice-contact gravel. The upper part of the sequence at Park Quarry is described in Brown (1993); nearby boreholes indicate that the workable material reaches a thickness of between 15.8 and 19.7 m.

The discontinuous spreads of glaciofluvial sand and gravel in the valley of the Burn of Sheeoch form flat-topped mounds and sinuous esker ridges trending north-eastwards. The sediments underlying the flat-topped mounds are typified by the coarsening upward deltaic sequence that was formerly exposed in Lochton Pit (NO 752 929). Up to 5.4 m of sandy gravel was recorded overlying laminated glaciolacustrine silt and clay in the floor of the pit; the uppermost parts of the Lochton sequence are described in Brown (1994). The esker deposits are characterised by interdigitating sequences of poorly sorted gravel, fine-grained sand and laminated silt and clay. They are more heterogeneous and hence less attractive sources of aggregate than some of the deltaic deposits.

[[File:P220858.jpg|left|thumbnail|Topset gravels overlying sandy deltaic foresets in the Lochton Sand and Gravel Formation, Cammie Wood, Feughside. P220858.]]
The most extensive spreads of sand and gravel in the valley of the Water of Feugh underlie the floodplain and river terraces upstream of Heugh-head (NO 687 928). Much of this material lies close to or below the water table, but mounds and kettled terraces on the southern side of the river valley, upstream of its confluence with the Burn of Knock, contain thick deposits of potentially workable sand and gravel. These deposits are typified by the glaciofluvial deltaic sediments exposed in the working pit at Cammie Wood (NO 695 920), where 12.8 m of sand and gravel occurs above the water table [[Media:P220858.jpg|(P220858)]]. The deposits coarsen upwards, from pebbly sand with partings of silt and clay into cross-bedded, fining-upward graded units of sandy gravel. The sandy gravel is overlain by up to 3 m of subhorizontally bedded coarse gravel that was laid down as the topset beds of the former ice-contact delta. The top of the sequence at Cammie Wood is described further in Brown (1994). Similar upward-coarsening sequences characterise many of the moundy glaciofluvial deposits between Scolly’s Cross (NO 642 877) and Pitdelphin Farm (NO 654 912), and also those forming large kames in the valley of the Devilly Burn, near Clatterin’ Brig (NO 665 782), in the southern part of Sheet 66E.

Small but attractive resources of coarse gravel, lying above the water table are present within esker systems in the vicinity of Strachan. Gravels forming the esker ridges, have been worked in pits north of Waulkmill (NO 647 923) and near Templeton (NO 671 916); however, significant unworked resources are present, within discontinuous esker ridges between Powlair and Greendams (NO 649 901).

The sands and gravels that form the undulating topography between Auchenblae and Drumlithie, and around Fettercairn, were laid down by meltwaters draining between ice in Strathmore and ice in the upland area to the north, which retreated north-westwards. These deposits characteristically occur as coarsening-upward sequences, which were laid down as deltas and fans into bodies of standing water between the two ice masses. The sands and gravels commonly contain thin waste partings of laminated silt and clay and some workable deposits (notably those south-east of Drumlithie) extend beneath a thin overburden of sandy ‘flow till’. These glaciofluvial sediments are assigned to the Drumlithie Sand and Gravel Formation of the [[Mearns Drift Group, Quaternary lithostratigraphy, Cainozoic of north-east Scotland|Mearns Drift Group]]. They contain a mixed assemblage of clasts with tough granitic and psammitic pebbles being derived from igneous and metamorphic terrain to the north and less resistant clasts of sandstone and andesitic volcanic rocks derived from the Old Red Sandstone succession in Strathmore.

The most laterally extensive resources lying above the water table in the vicinity of Auchenblae, occur as flat-topped mounds. These deposits were worked in a large pit at Drumsleed (NO 733 776), where 5 m of sandy gravel was formerly exposed, overlying 13 m of pebbly sand. Exposures in other disused workings indicate that some of the nearby flat-topped deposits are much thinner, and range in composition from clayey gravel, to medium- and coarse-grained sand. Farther to the east, the glaciofluvial deposits become more hummocky and form a series of east-trending ridges that are extensively dissected by glacial drainage channels. The workable deposits of sand and gravel within the ridges range from 1.8 m to over 23.1 m in thickness, and have a similar range of grading characteristics to the deposits forming the flat-topped mounds.

The discontinuous spreads of sand and gravel beneath the floodplains of the Bervie Water, Luther Water, Black Burn, Devilly Burn and Burn of Cauldcots are relatively unattractive sources of aggregate as most lie beneath the water table. However, the last two named burns dissect extensive deposits of sand and gravel of the Drumlithie Sand and Gravel Formation that form moundy and terraced spreads around Fettercairn. None of these deposits has been assessed in detail, but notable resources are thought to occur on the lower flanks of Tor Hill, between Thornhill (NO 630 725) and Fettercairn, around Stankeye (NO 643 745), Kincardine Castle (NO 671 751), and at Nether Thainston (NO 634 750).

Sands and gravels lying above the water table are present within ice-contact glaciofluvial sequences in two areas at the eastern edge of Sheet 66E. Significant resources of gravel and coarse-grained sand have been worked in several small pits in the valley of the Cowie Water, around Snob Cott (NO 801 885). They also extend downstream on to the adjoining Sheet 67 Stonehaven. The surrounding moundy glacial deposits have also been worked on a small scale, though the resource is commonly thin, bouldery and laterally discontinuous.

Mounds and ridges of ice-contact sand and gravel on the eastern side of the valley drained by the Carron Water, and the Forthie Water between Brenzieshill (NO 799 792) and Pitdrichie (NO 795 825), have been worked for gravel in several places. The deposits forming the Bridge of Fiddes Esker are largely worked out, whereas up to 18.7 m of gravel was recorded in 1989 from active workings in an esker ridge near Pitdrichie. In contrast, the Little Wards Esker, which forms a discontinuous ridge, extending south-south-westwards for a distance of 1.5 km from the vicinity of Bridgend (NO 803 789), had only been exploited in small piecemeal workings at the time of the assessment. Noteworthy resources were also present within the more extensive glaciofluvial spreads, but the deposits are generally thinner and more sandy than those forming the eskers.

[[File:P915336.png|thumbnail|Composition of workable gravel deposits south of Aberdeen. P915336.]]
The gravels in the northern portion of Sheet 66E are of similar composition to most of those in the southern part of Sheet 76E, to the north. Clasts of granite and felsite (microgranite) predominate [[Media:P915336.png|(P915336)]]. Most are derived from the Mount Battock Granite, which forms the high ground between the catchments of the Dee, Bervie Water, Carron Water and Cowie Water. Psammitic clasts become more numerous within the glaciofluvial and alluvial gravels in the Dee valley, downstream of Banchory and significant numbers of pebbles of basic igneous rocks are present in gravels forming south-east-trending eskers in the vicinity of Strachan.

The glaciofluvial deposits of the Drumlithie Sand and Gravel Formation in the southern part of Sheet 66E contain a high proportion of quartzite and andesite pebbles, many of which have been reworked from local Devonian conglomerates. Some granitic clasts are also present, but the gravels contain a much higher proportion of deleterious material than those in the northern part of Sheet 66E. The friable clasts, which are mainly Devonian mudstone and sandstone pebbles, significantly reduce the strength of the aggregate and its suitability for use in concrete and road construction (see aggregate test results below).

End-use suitability data are only available for the sand and gravel resources in the valley of the River Dee downstream of Banchory, the valley of Burn of Sheeoch, and the sandy lacustrine sediments near Lochhead of Leys and Loch of Park. The glaciofluvial deposits, downstream of Banchory appear to be suitable for most end uses and as ‘all in’ concrete aggregate. The resources in the valley of the Burn of Sheeoch are more variable, with the glaciofluvial sheet deposits near Mains of Blairydrine (NO 742 943) being the most attractive as a source of fine aggregate for asphalt, plaster, mortar and concrete. Some of the lacustrine sediments are also suitable for use as asphalt, plaster, mortar and concrete sand, but the deposits are generally rather thin and variable.

== References ==
[[References, Cainozoic of north-east Scotland|Full reference list]]

[[Category:Grampian Highlands]]

Sand and gravel resources, Sheet 66E Banchory, Cainozoic of north-east Scotland

2015-09-16T10:26:52Z

Lmo:

'''From: Merritt, J W, Auton, C A, Connell, E R, Hall, A M, and Peacock, J D. 2003. [[Cainozoic geology and landscape evolution of north-east Scotland. Memoir of the British Geological Survey, sheets 66E, 67, 76E, 77, 86E, 87W, 87E, 95, 96W, 96E and 97 (Scotland)|Cainozoic geology and landscape evolution of north-east Scotland]]. Memoir of the British Geological Survey, sheets 66E, 67, 76E, 77, 86E, 87W, 87E, 95, 96W, 96E and 97 (Scotland).'''
__FORCETOC__
= Sheet 66E Banchory =
[[File:P915380.png|thumbnail|Glacial and glaciofluvial features and the distribution of glacigenic deposits on Sheet 66E Banchory. P915380.]]
The principal resources of the northern part of Sheet 66E [[Media:P915380.png|(P915380)]] occur within glaciofluvial and alluvial deposits in the valleys of the River Dee, Burn of Sheeoch and Burn of Canny. Extensive spreads of sand and gravel are also present in the valley of the Water of Feugh, in the vicinity of Strachan. Minor resources occur within terraced alluvial deposits and moundy glaciofluvial deposits in Glen Dye and as flat-lying spreads of sand, in a small lake basin near Lochhead of Leys (NO 695 979) and in a larger basin around Loch of Park (NJ 770 990).

Some potentially workable coarse aggregate, mixed with bouldery diamicton, is present within the moundy glacial deposits forming moraines to the north and east of Loch of Park. Similar morainic sediments also occur in the valleys of the Water of Aven, the Burn of Melmannoch, the Burn of Knock, and on the southern side of the valley of the Water of Feugh, in the vicinity of Powlair (NO 620 912). All are potential sources of low-grade aggregate. Discrete areas of deeply decomposed granitic bedrock, around Loch of Park, Powlair and the upper reaches of Garrol Burn also constitute sources of aggregate suitable for use as fill and road base.

In the southern part of Sheet 66E, the main spreads of sand and gravel form moundy topography on the northern margin of Strathmore, notably between Auchenblae and Drumlithie, and around Fettercairn. Less attractive deposits are present beneath the floodplains of the Bervie Water, Luther Water, Black Burn, Devilly Burn and Burn of Cauldcots, as well as in the discontinuous terraced spreads on the sides of the valleys. Deeply weathered exposures of Lower Devonian conglomerate north of the Glen of Drumtochty, constitute a resource of cobbly gravel which, in places, exceeds 3 m in thickness.

The sand and gravel resources in the Dee valley, downstream of Banchory and within the valley of the Burn of Sheeoch, were evaluated as part of Mineral Assessment Report 148. Those in the vicinity of Strachan and in Strathmore were included in MAR 149. The sands and gravels that crop out in the south-west corner of Sheet 66E have not been assessed in detail. They are described in Carroll (1995d).

The kettled terraces that flank the Dee, between Banchory and the eastern margin of Sheet 66E, contain extensive resources of well stratified gravel and sand, lying above the water table; they average 7.4 m in thickness. Gravelly deposits, beneath negligible overburden are also present underlying the floodplain; they average 10.4 m in thickness. The terraced glaciofluvial gravels have been worked to a depth of greater than 10 m in Park Quarry, near Gallow Hill (NO 806 978), where they merge into mounds and ridges of ice-contact gravel. The upper part of the sequence at Park Quarry is described in Brown (1993); nearby boreholes indicate that the workable material reaches a thickness of between 15.8 and 19.7 m.

The discontinuous spreads of glaciofluvial sand and gravel in the valley of the Burn of Sheeoch form flat-topped mounds and sinuous esker ridges trending north-eastwards. The sediments underlying the flat-topped mounds are typified by the coarsening upward deltaic sequence that was formerly exposed in Lochton Pit (NO 752 929). Up to 5.4 m of sandy gravel was recorded overlying laminated glaciolacustrine silt and clay in the floor of the pit; the uppermost parts of the Lochton sequence are described in Brown (1994). The esker deposits are characterised by interdigitating sequences of poorly sorted gravel, fine-grained sand and laminated silt and clay. They are more heterogeneous and hence less attractive sources of aggregate than some of the deltaic deposits.

[[File:P220858.jpg|left|thumbnail|Topset gravels overlying sandy deltaic foresets in the Lochton Sand and Gravel Formation, Cammie Wood, Feughside. P220858.]]
The most extensive spreads of sand and gravel in the valley of the Water of Feugh underlie the floodplain and river terraces upstream of Heugh-head (NO 687 928). Much of this material lies close to or below the water table, but mounds and kettled terraces on the southern side of the river valley, upstream of its confluence with the Burn of Knock, contain thick deposits of potentially workable sand and gravel. These deposits are typified by the glaciofluvial deltaic sediments exposed in the working pit at Cammie Wood (NO 695 920), where 12.8 m of sand and gravel occurs above the water table [[Media:P220858.jpg|(P220858)]]. The deposits coarsen upwards, from pebbly sand with partings of silt and clay into cross-bedded, fining-upward graded units of sandy gravel. The sandy gravel is overlain by up to 3 m of subhorizontally bedded coarse gravel that was laid down as the topset beds of the former ice-contact delta. The top of the sequence at Cammie Wood is described further in Brown (1994). Similar upward-coarsening sequences characterise many of the moundy glaciofluvial deposits between Scolly’s Cross (NO 642 877) and Pitdelphin Farm (NO 654 912), and also those forming large kames in the valley of the Devilly Burn, near Clatterin’ Brig (NO 665 782), in the southern part of Sheet 66E.

Small but attractive resources of coarse gravel, lying above the water table are present within esker systems in the vicinity of Strachan. Gravels forming the esker ridges, have been worked in pits north of Waulkmill (NO 647 923) and near Templeton (NO 671 916); however, significant unworked resources are present, within discontinuous esker ridges between Powlair and Greendams (NO 649 901).

The sands and gravels that form the undulating topography between Auchenblae and Drumlithie, and around Fettercairn, were laid down by meltwaters draining between ice in Strathmore and ice in the upland area to the north, which retreated north-westwards. These deposits characteristically occur as coarsening-upward sequences, which were laid down as deltas and fans into bodies of standing water between the two ice masses. The sands and gravels commonly contain thin waste partings of laminated silt and clay and some workable deposits (notably those south-east of Drumlithie) extend beneath a thin overburden of sandy ‘flow till’. These glaciofluvial sediments are assigned to the Drumlithie Sand and Gravel Formation of the Mearns Drift Group (see Chapter 8). They contain a mixed assemblage of clasts with tough granitic and psammitic pebbles being derived from igneous and metamorphic terrain to the north and less resistant clasts of sandstone and andesitic volcanic rocks derived from the Old Red Sandstone succession in Strathmore.

The most laterally extensive resources lying above the water table in the vicinity of Auchenblae, occur as flat-topped mounds. These deposits were worked in a large pit at Drumsleed (NO 733 776), where 5 m of sandy gravel was formerly exposed, overlying 13 m of pebbly sand. Exposures in other disused workings indicate that some of the nearby flat-topped deposits are much thinner, and range in composition from clayey gravel, to medium- and coarse-grained sand. Farther to the east, the glaciofluvial deposits become more hummocky and form a series of east-trending ridges that are extensively dissected by glacial drainage channels. The workable deposits of sand and gravel within the ridges range from 1.8 m to over 23.1 m in thickness, and have a similar range of grading characteristics to the deposits forming the flat-topped mounds.

The discontinuous spreads of sand and gravel beneath the floodplains of the Bervie Water, Luther Water, Black Burn, Devilly Burn and Burn of Cauldcots are relatively unattractive sources of aggregate as most lie beneath the water table. However, the last two named burns dissect extensive deposits of sand and gravel of the Drumlithie Sand and Gravel Formation that form moundy and terraced spreads around Fettercairn. None of these deposits has been assessed in detail, but notable resources are thought to occur on the lower flanks of Tor Hill, between Thornhill (NO 630 725) and Fettercairn, around Stankeye (NO 643 745), Kincardine Castle (NO 671 751), and at Nether Thainston (NO 634 750).

Sands and gravels lying above the water table are present within ice-contact glaciofluvial sequences in two areas at the eastern edge of Sheet 66E. Significant resources of gravel and coarse-grained sand have been worked in several small pits in the valley of the Cowie Water, around Snob Cott (NO 801 885). They also extend downstream on to the adjoining Sheet 67 Stonehaven. The surrounding moundy glacial deposits have also been worked on a small scale, though the resource is commonly thin, bouldery and laterally discontinuous.

Mounds and ridges of ice-contact sand and gravel on the eastern side of the valley drained by the Carron Water, and the Forthie Water between Brenzieshill (NO 799 792) and Pitdrichie (NO 795 825), have been worked for gravel in several places. The deposits forming the Bridge of Fiddes Esker are largely worked out, whereas up to 18.7 m of gravel was recorded in 1989 from active workings in an esker ridge near Pitdrichie. In contrast, the Little Wards Esker, which forms a discontinuous ridge, extending south-south-westwards for a distance of 1.5 km from the vicinity of Bridgend (NO 803 789), had only been exploited in small piecemeal workings at the time of the assessment. Noteworthy resources were also present within the more extensive glaciofluvial spreads, but the deposits are generally thinner and more sandy than those forming the eskers.

[[File:P915336.png|thumbnail|Composition of workable gravel deposits south of Aberdeen. P915336.]]
The gravels in the northern portion of Sheet 66E are of similar composition to most of those in the southern part of Sheet 76E, to the north. Clasts of granite and felsite (microgranite) predominate [[Media:P915336.png|(P915336)]]. Most are derived from the Mount Battock Granite, which forms the high ground between the catchments of the Dee, Bervie Water, Carron Water and Cowie Water. Psammitic clasts become more numerous within the glaciofluvial and alluvial gravels in the Dee valley, downstream of Banchory and significant numbers of pebbles of basic igneous rocks are present in gravels forming south-east-trending eskers in the vicinity of Strachan.

The glaciofluvial deposits of the Drumlithie Sand and Gravel Formation in the southern part of Sheet 66E contain a high proportion of quartzite and andesite pebbles, many of which have been reworked from local Devonian conglomerates. Some granitic clasts are also present, but the gravels contain a much higher proportion of deleterious material than those in the northern part of Sheet 66E. The friable clasts, which are mainly Devonian mudstone and sandstone pebbles, significantly reduce the strength of the aggregate and its suitability for use in concrete and road construction (see aggregate test results below).

End-use suitability data are only available for the sand and gravel resources in the valley of the River Dee downstream of Banchory, the valley of Burn of Sheeoch, and the sandy lacustrine sediments near Lochhead of Leys and Loch of Park. The glaciofluvial deposits, downstream of Banchory appear to be suitable for most end uses and as ‘all in’ concrete aggregate. The resources in the valley of the Burn of Sheeoch are more variable, with the glaciofluvial sheet deposits near Mains of Blairydrine (NO 742 943) being the most attractive as a source of fine aggregate for asphalt, plaster, mortar and concrete. Some of the lacustrine sediments are also suitable for use as asphalt, plaster, mortar and concrete sand, but the deposits are generally rather thin and variable.

== References ==
[[References, Cainozoic of north-east Scotland|Full reference list]]

[[Category:Grampian Highlands]]

Sand and gravel resources, Sheet 86E Turriff, Cainozoic of north-east Scotland

2015-09-16T10:21:28Z

Lmo: /* Sheet 86E Turriff */

Sand and gravel resources, Sheet 87E Peterhead, Cainozoic of north-east Scotland

2015-09-16T10:20:27Z

Lmo:

Sand and gravel resources, Sheet 77 Aberdeen, Cainozoic of north-east Scotland

2015-09-16T10:17:50Z

Lmo:

Sand and gravel resources, Sheet 77 Aberdeen, Cainozoic of north-east Scotland

2015-09-16T10:16:12Z

Lmo: /* Sheet 77 Aberdeen */

Sand and gravel resources, Sheet 77 Aberdeen, Cainozoic of north-east Scotland

2015-09-16T10:15:42Z

Lmo:

Sand and gravel resources, Sheet 76E Inverurie, Cainozoic of north-east Scotland

2015-09-16T09:30:36Z

Lmo:

Sand and gravel resources, Sheet 87E Peterhead, Cainozoic of north-east Scotland

2015-09-16T09:27:27Z

Lmo:

Sand and gravel resources, Sheet 87E Peterhead, Cainozoic of north-east Scotland

2015-09-16T09:25:27Z

Lmo: /* Sheet 87E Peterhead */

Sand and gravel resources, Sheet 87E Peterhead, Cainozoic of north-east Scotland

2015-09-16T09:24:16Z

Lmo:

Sand and gravel resources, Sheet 87W Ellon, Cainozoic of north-east Scotland

2015-09-16T08:55:07Z

Lmo:

Sand and gravel resources, Sheet 86E Turriff, Cainozoic of north-east Scotland

2015-09-16T08:52:33Z

Lmo:

Sand and gravel resources, Sheet 86E Turriff, Cainozoic of north-east Scotland

2015-09-16T08:49:50Z

Lmo:

Sand and gravel resources, Sheet 97 Fraserburgh, Cainozoic of north-east Scotland

2015-09-16T08:43:44Z

Lmo: /* Sheet 97 Fraserburgh */

Sand and gravel resources, Sheet 97 Fraserburgh, Cainozoic of north-east Scotland

2015-09-16T08:43:21Z

Lmo: /* Sheet 97 Fraserburgh */

Sand and gravel resources, Sheet 97 Fraserburgh, Cainozoic of north-east Scotland

2015-09-16T08:41:51Z

Lmo:

Sand and gravel resources, Sheet 96E Banff, Cainozoic of north-east Scotland

2015-09-16T08:39:25Z

Lmo:

Sand and gravel resources, Sheet 96W Portsoy, Cainozoic of north-east Scotland

2015-09-16T08:37:29Z

Lmo:

Sand and gravel resources, Sheet 95 Elgin, Cainozoic of north-east Scotland

2015-09-16T08:28:54Z

Lmo: /* Sheet 95 Elgin */

Sand and gravel resources, Sheet 95 Elgin, Cainozoic of north-east Scotland

2015-09-16T08:27:38Z

Lmo:

Aggregate testing results, Cainozoic of north-east Scotland

2015-09-15T13:32:01Z

Lmo:

Aggregate testing results, Cainozoic of north-east Scotland

2015-09-15T13:29:48Z

Lmo:

Aggregate testing results, Cainozoic of north-east Scotland

2015-09-15T13:28:17Z

Lmo:

Aggregate testing results, Cainozoic of north-east Scotland

2015-09-15T13:20:17Z

Lmo:

History of sand and gravel resource appraisal, Cainozoic of north-east Scotland

2015-09-15T13:03:56Z

Lmo:

History of sand and gravel resource appraisal, Cainozoic of north-east Scotland

2015-09-15T13:02:46Z

Lmo:

History of sand and gravel resource appraisal, Cainozoic of north-east Scotland

2015-09-15T13:01:34Z

Lmo:

History of sand and gravel resource appraisal, Cainozoic of north-east Scotland

2015-09-15T12:59:52Z

Lmo:

History of sand and gravel resource appraisal, Cainozoic of north-east Scotland

2015-09-15T12:59:12Z

Lmo:

Burn of Benholm - locality, Cainozoic of north-east Scotland

2015-09-15T12:55:11Z

Lmo:

'''From: Merritt, J W, Auton, C A, Connell, E R, Hall, A M, and Peacock, J D. 2003. [[Cainozoic geology and landscape evolution of north-east Scotland. Memoir of the British Geological Survey, sheets 66E, 67, 76E, 77, 86E, 87W, 87E, 95, 96W, 96E and 97 (Scotland)|Cainozoic geology and landscape evolution of north-east Scotland]]. Memoir of the British Geological Survey, sheets 66E, 67, 76E, 77, 86E, 87W, 87E, 95, 96W, 96E and 97 (Scotland).'''
__FORCETOC__
= Burn of Benholm =
The shelly pebbly clays and peat lenses exposed beneath the Mill of Forest Till at the Burn of Benholm, provide new insights into the glacial history of eastern Scotland prior to the Late Devensian. The peat lenses are remnants of an Early Devensian interstadial deposit of OIS 5c or 5a age. Amino-acid ratios indicate that shells in the underlying clays are of OIS 9 age or older, and the fabric and composition of the shelly sediments are consistent with their emplacement as glacially deformed rafts of marine sediment. The rafts were transported onshore when Scandinavian ice occupied the North Sea basin, during a pre-Late Devensian glacial episode.

[[File:P915381.png|left|thumbnail|Glacial and glaciofluvial features and the distribution of glacigenic deposits on Sheet 67 Stonehaven. P915381.]]
[[File:P220762.jpg|thumbnail|Sheared lens of the Burn of Benholm Peat Bed within olive grey shelly clay and diamicton. P220762.]]
Exposures in the banks of the Burn of Benholm, 14 km north of Montrose [[Media:P915381.png|(P915381)]], have for many years revealed a Quaternary sequence that includes a dark grey clay containing fragmentary marine shells, overlain by reddish brown till. In one exposure lenses of peat and organic silt intervened between the units [[Media:P220762.jpg|(P220762)]]; most of the lenses were incorporated within the red till, near to its base (Campbell, 1934; Donner, 1960, 1979).

Particular controversy has focused on the age and origin of the shelly clay and on the age and biostratigraphical significance of the peat lenses (Gordon, 1993d). The shelly clay has been interpreted as a till deposited by ice moving onshore, at a time when Scottish and Scandinavian ice sheets coalesced in the North Sea basin (Campbell, 1934; Bremner, 1938; Donner, 1960). More recently, Sutherland (1981) proposed that the shelly sediment is an in situ cold water marine deposit formed as a result of significant isostatic loading during an Early Devensian glaciation.

[[File:P915333.png|thumbnail|Excavations and measured sections at the Burn of Benholm. P915333.]]
A pollen assemblage from peat collected by Campbell was subsequently described by Bremner (1943) as containing thermophilous tree pollen, and interpreted by him as indicating an interglacial environment. Later pollen analyses of the peat lenses, however, showed spectra dominated by non-arboreal types representing herb communities (Donner, 1960, 1979). This suggested an interstadial, rather than interglacial origin for the peat, which Donner (1960) initially interpreted as being of Late-glacial (Windermere) Interstadial age. He also proposed that the overlying red till was emplaced by landslipping, or gelifluction during the Loch Lomond Stadial a comparable origin to that proposed here for the Knockhill Wood succession (see above). A sample of the Burn of Benholm peat (Hel–1098) subsequently yielded a radiocarbon age of greater than 42 000 BP, which led Donner (1979) to reinterpret its age as being Early or Middle Devensian and the red till as being of the Main Late Devensian glaciation.

Because of the conflicting interpretations of the origin of the shelly clay and of the palaeoenvironmental conditions represented by the pollen in the peat deposits, a reinvestigation of the deposits at Burn of Benholm has been undertaken recently (Auton et al., 2000). The work included new excavations ([[Media:P915333.png|(P915333)]] adjacent to the stream sections first described by Campbell. One of these, trial pit BBP 4, revealed a new exposure of peat lenses beneath the base of the red till.

The Burn of Benholm site (NO 795 691) comprises a series of stream sections and trial pits at about 45 m OD along the Burn of Benholm. The lithostratigraphy is summarised in the table below. The sections and trial pits clearly show the Mill of Forest Till overlying Benholm Clay Formation in the manner described by Campbell (1934). In some of the exposures a sharp, undulating contact, varying from subhorizontal to steeply dipping, occurs between the two formations. In other sections, such as BBP 2, a zone of shearing and churning occurs with red-brown till mixed with a more gravelly unit at the top of the Benholm Clay. In trial pit BBP 4 sheared and folded lenses of peat and sandy silt occur within this gravelly unit. In section RC 1 deformed units of Mill of Forest Till and the underlying Birnie Gravel abut a knoll of andesite bedrock.

{| class="wikitable"
|+ style="caption-side:top;"|Lithostratigraphy in the vicinity of the Burn of Benholm.
|-
! Lithostratigraphical unit||Lithology||Typical thickness (m)
|- valign="top"
| Drumlithie Sand and Gravel Formation (1)||Rounded cobble gravel||up to 1.20
|- valign="top"
| Mill of Forest Till Formation (1)||Stiff, moderate reddish brown, sandy clayey stony diamicton, containing clasts derived from the Devonian bedrock of Strathmore||up to 1.30
|- valign="top"
| Burn of Benholm Peat Bed (2)||Peat and humic clay as sheared lenses in overlying till and underlying clay||up to 0.15
|- valign="top"
| Benholm Clay Formation (2)||Stiff, olive-grey, calcareous, silty clay and clayey diamicton; with well dispersed clasts and fragments of marine shells, including Arctica islandica (L.). Clasts include basalt, gneiss, troctolite, limestone (including chalk), shale, flint and jet, as well as Lower Old Red Sandstone lithologies||up to 3.00
|- valign="top"
| Birnie Gravel Formation (3)||Moderate brown, clayey gravel||up to 3.00
|- valign="top"
| Bedrock||Andesite||
|-
|colspan="3"|(1) Mearns Drift Group, (2) Logie-Buchan Drift Group, (3) East Grampian Drift Group
|}

Clast orientations measured from the Mill of Forest Till all display tightly clustered fabrics suggesting subglacial deposition and indicate a north-easterly to east-north-easterly direction of ice movement. In contrast, eastwardly dipping stratification and north-westwardly dipping sheared contacts within the Benholm Clay, together with clasts of Mesozoic and Palaeozoic rocks are compatible with glacitectonic transport of the unit from offshore.

A sparse assemblage of fragmentary bivalve molluscs (some of which are ‘polished’ and striated) has been recovered from the Benholm Clay Formation. The assemblage included ''Arctica islandica, Macoma balthica, Cersatoderma edule ''and ''Mya ''sp. and is of boreal to low arctic aspect, but suggests no particular age other than, broadly ‘Late Pleistocene’. Samples from the Benholm Clay have also yielded rich palynomorph assemblages, which were completely dominated by Early Carboniferous, Early and Late Cretaceous and Palaeogene forms (Harland, 1993). This reworked material was probably derived from the North Sea basin. Small numbers of Quaternary dinoflagellate cysts were also recorded. Two main taxa were recognised: ''Protoperidinium ''sp. and ''Bitectatodinium tepikiense''. Both are indicative of north-temperate to arctic, cold-water marine environments, possibly in close proximity to ice (Harland, 1983; Dale, 1985). A sparse assemblage of agglutinating foraminifera was found in two samples from the clay (Wilkinson, 1993). All of the foraminifera are considered to be reworked and, although their age is unknown, it is unlikely that they are younger than Palaeogene. The paucity of indigenous microfossils and the abundance of reworked material are consistent with interpretation of the clay as a former offshore deposit, reworked and transported onshore by ice.

Pollen analyses were carried out by M J C Walker on four samples of organic material from the Burn of Benholm Peat Bed exposed in Trial Pit BBP 4 and are reported fully in Auton et al. (2000). The pollen spectra in all four samples are broadly similar and are comparable to those reported by Donner (1960, 1979), although a wider range of taxa has been recorded. Collectively, the pollen evidence points to an open tundra vegetation of damp heath and grassland, with patches of low scrub, and isolated stands of tree birch probably in more sheltered localities. This confirms the view that the site probably does not contain an interglacial record; rather, it represents an interstadial episode with summer temperatures slightly below those of the present day.

A distinctive feature of the pollen spectra is the occurrence of a number of grains resembling ''Bruckenthalia spiculifolia''. ''Bruckenthalia ''pollen has been found at a number of interglacial sites in north-west Europe (e.g. Turner, 1970; Menke and Behre, 1973; Phillips, 1976; Hall, 1980), although the species appears to be more typically associated with Early Weichselian to Early Devensian Interstadial deposits (Whittington, 1994). Indeed, ''Bruckenthalia spiculifolia ''has been cited as a biostratigraphical marker for Early Weichselian Interstadials (Pons et al., 1992). Bruckenthalia has also been found at the Crossbrae Farm and Camp Fauld (Moss of Cruden) sites described above, which may also be of Early Devensian age (Whittington et al., 1993, 1998; Whittington, 1994).

Three sets of ‘total’ amino-acid D/L (D-alloisoleucene: L-isoleucene) ratios have been determined on fragmentary shells of ''Arctica islandica ''collected from the Benholm Clay Formation in section RC 1. They are 0.37 (AAL 2950), 0.37 and 0.38 (AAL 2952) and 0.34 ± 0.024 (LOND 400). The third analysis (Lond 400) is regarded as the most accurate.

[[File:P915347.png|centre|600px|thumbnail|Correlation of lithostratigraphical units in north-east Scotland. P915347.]]
Conventional radiocarbon dating was carried out on a single bulk sample taken from a lens of the Burn of Benholm Peat in the upper part of the Benholm Clay Formation, between 2.0 and 2.3 m depth in trial pit BBP 4. The acid-insoluble residue was subdivided into its alkali soluble (humic) and alkali insoluble (humin) components for independent age measurement. The humic carbon sample, SRR–5201a, gave a radiocarbon age of greater than 50 850 14C years BP; the humin sample, SRR–5201b, one of greater than 50 600 14C years BP. Both dates are older than the upper limit of the radiocarbon chronology and provide a minimum (Mid-Devensian) age for the Benholm Peat.

[[File:P915280.png|thumbnail|Quaternary stratigraphy of the central North Sea. P915280.]]
The interstadial affinity of the pollen, the presence of ''Bruckenthalia spiculifolia ''and infinite radiocarbon dates from the Burn of Benholm Peat Bed, all suggest that the peat lenses are remnants of an Early Devensian interstadial deposit of OIS 5c or 5a age or older [[Media:P915347.png|(P915347)]].

Amino-acid ratios from the fragments of ''Arctica islandica ''suggest that the shells within the Benholm Clay Formation are of OIS 9 age or older. The fabric and composition of these shelly sediments are consistent with their emplacement as immature deformation till, formed by partial homogenisation of glacially transported rafts of marine sediment. The amino-acid ratios suggest that this till was deposited by ice during a post-OIS 9/11 glaciation. It may be derived from offshore sediments within the Coal Pit Formation, which is of probable Saalian to Weichselian age (Stoker et al., 1985), or from the Ling Bank Formation (which contains an interval of Holsteinian age), or correlate with a till within the Fisher Formation, of supposed Saalian age (Gatliff et al., 1994) [[Media:P915280.png|(P915280)]]. Folded and sheared contacts between the shelly deposits, the peat lenses and the Mill of Forest Till indicate that the fossiliferous sediments were glacitectonised during the Main Late Devensian glaciation, when ice from within Strathmore overrode the site from the south-west.

== References ==
[[References, Cainozoic of north-east Scotland|Full reference list]]

[[Category:Grampian Highlands]]
[[Category: 4. Grampian Highlands]]