Organic deposits, Quaternary, Cainozoic of north-east Scotland

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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).

Contributors: J F Aitken, D F Ball, D Gould, J D Hansom, R Holmes, R M W Musson and M A Paul.

Organic deposits[edit]

Peat[edit]

Deposits of basin peat in the district occur mostly within the sites of former lochans. Commonly, the peat contains tree boles and other woody fragments as well as the partially decomposed, acidic remains of sedges, reeds, rushes, Sphagnum and heather. Most raised peat mosses are a fraction of the original size because of their exploitation for fuel in historical times. Today, many deposits barely average even one metre in thickness, but they remain waterlogged and would partially regenerate in time. Many peaty hollows have been partly, if not completely infilled with boulders carted off the fields. Others have provided sites for dumping waste materials. Peat resources are discussed in Bulk mineral resources and the locality and extent of the main deposits are listed below.

Potential peat resources between Aberdeen and Elgin (based on Fraser, 1948)
Sheet Name Type of peat Condition (2) Altitude (m) Area (ha) Maximum thickness (m)
95 Broken Moan Basin 33% cut over 275 10 -
96W Aultmorehill Moss (1) Hill Unexploited 235 80 2.4
96W Old Fir Hill- Hill of Moss, Clashmadin Hill & Basin 25% cut over 235 60 4.3
96W Sheil Muir Moss Basin Mostly cut over 200 60
96W Hill of Ord Basin Mostly cut over 160 8
96E Moss of Clochforbie- Moss of Byth Basin All cut over, partly reclaimed 150 - -
96E Moss of Fishrie (1) Hill 25% removed 190 280 2.4
97 Moss of Bracklemore (1) Basin 50% disturbed by cutting 130 150 6.1
97 Windyheads Hill Basin All cut over 170 - -
97 Moss of Blackrigg Basin 75% cut over 90 30 4.9
97 Mosses of Skelmanae and Auchmacleddie Basin All cut over 90 100 4.3
97 Montsolie Basin All cut over 100 -
97 Mosses of Middlemuir (1) Basin 33% cut over 100 400 4.3 (3)
86E Cuminestown Hill and Basin 75% cut over 150 80 2.1
86E Moss of Swanford (1) Basin Mostly cut over 90 25 2.1
86E Mosses NE of Fyvie Basin All cut over 110 120 1.2
86E Mosses at Leet, Cairns and Heatherybanks Basin All cut over 110 40 2.4
86E Wartle Moss Basin Mostly cut over 120 100 -
86E Moss of Redhill Basin Mostly cut over 150 25 -
87W Mosses at Cowbog Hill & Basin 75% cut over 135 120 6.1
87W Mosses at Nittanshead Hill & Basin Mostly cut over 175 180 3.7
87W Craigculter Moss Basin 25% cut over 120 40 3.7
87W Mosses N of New Leeds Basin Mostly cut over 75 60 4.3
87W Mosses of Auchleuchries and Muirtack Basin All cut over 75 60 -
87W Moss of Dudwick Hill All disturbed by cutting 105 65 -
87W Mosses of Elrick and Annochie Basin All cut over 110 - -
87E Mosses of Crimond and Logie Basin 50% cut over 60 160 4.3
87E St Fergus Moss Basin 50% disturbed by cutting 45 220 6.1 (3)
87E Rora Moss Hill 50% cut over 55 400 2.7
87E Mosses of the Cruden Hills Hill & Basin 20% cut over 115 600 2.4 (3)
87E Moss of Kinmundy Basin Mostly cut over 75 55 4.3
87E Moss of Lochlundie Basin 70% disturbed by cutting 75 240 6.1
76E Skene Moss Basin 75% cut over 100 30 3.5 (3)
76E Mosses of Air and Lochside Basin 75% disturbed by cutting 100 60 4.3 (3)
76E Springhill Moss Basin 50% cut over 75 25 3.7
76E Luechar Moss Basin 90% cut over 75 35 -
76E Red Moss at Candyglirach Basin 66% cut over 75 240 3.0 (3)
76E Mosses of Blacknose and Lochmuir (1) Basin All disturbed by cutting 70 260 1.9
76E Hill of Fare Hill & Basin Wide area removed 250 10 4.6
77 Burreldale Moss Basin 75% cut over 150 120 4.3 (3)
77 Moss of Logierieve Basin All cut over 60 30 -
77 Moss of Pettymuck Basin All cut over 60 12 -
77 North Moss of Ardo Basin Mostly cut over 75 15 -
77 Mosses of Ardo, Wardhillock and Harestone Basin Extensively cut over 70 20 4.6
77 Red Moss between Belhelvie and Dyce Basin 60% cut over 90 200 3.7 (3)
77 Grandholm Moss Basin All cut over 70 20 -
(1) Deposit extends onto adjoining sheet.

(2) Refers to the condition of the peat evaluated at the time of Fraser's study: many of the deposits have been worked entensively on piecemeal basis since 1948. Cut over - indicates that the top layer of peat was partially or completely extracted; deeper layers remain intact.

(3) Cross-section of moss and representative peat profile in Glentworth and Muir (1963).

Glacial and glaciofluvial features and the distribution of glacigenic deposits on Sheet 77 Aberdeen. P915379.
Glacial and glaciofluvial features and the distribution of glacigenic deposits on Sheet 87W Ellon. P915376.

Many basins are ice-scoured hollows in bedrock, such as Harestone Moss (NJ 932 195), which is underlain by ultra-basic igneous rocks north-east of Belhelvie (P915379), and those formed on granite around New Pitsligo and Strichen (P915376), which contain significant resources of peat. Many small basins are kettleholes in glaciofluvial sands and gravels or morainic deposits, such as large parts of Red Moss (NJ 747 014) and Leuchar Moss (NJ 788 047), on Sheet 76E Inverurie. The majority of basins, however, are ice-moulded hollows in till; abundant examples occur on Sheet 76E, for example Skene Moss (NJ 757 107) and Braigies Moss (NJ 758 047). They are also common on Sheet 87W Ellon (for example the Moss of Belnagoak (NJ 880 428) and Elrick Moss (NJ 954 418)), on Sheet 86E Turriff (for example between Cuminestown and the Ythan gorge) and on Sheet 77 Aberdeen (for example Burreldale Moss (NJ 829 239) and several mosses in the vicinity of Westfield (NJ 946 207)). Deposits of peat rest on raised marine and glaciomarine clays within hollows between Kinloss and Lossiemouth on Sheet 95 Elgin.

Glacial and glaciofluvial features and the distribution of glacigenic deposits on Sheet 87E Peterhead. P915377.

Some of the most extensive spreads of low-lying blanket peat in the district rest on particularly clayey and impermeable deposits of till, such as those of the Banffshire Coast Drift Group beneath Rora Moss (NK 045 515) and St Fergus Moss (NK 055 536) (P915377), and several mosses around New Pitsligo (P915376). Peat has developed on stiff red till of the Logie-Buchan Drift Group at Lochlundie Moss, 5 km south-west of Cruden Bay on Sheet 87E Peterhead.

Glacial and glaciofluvial features and the distribution of glacigenic deposits on Sheet 97 Fraserburgh. P915374.

Hill peat is most extensive on the granite outcrops in the south of the district, where tree roots and stumps, particularly of Scots pine, are very common. Blanket peat covers parts of Bennachie and the Hill of Fare on Sheet 76E Inverurie and on hilly areas underlain by the Mount Battock granite on Sheet 66E Banchory, where it is relatively thick and widespread. For example, up to 4 m of peat overlying decomposed granite is exposed beside a forestry track on the south-west side of Kerloch (NO 697 879). Other spreads include those on the flaggy quartzites forming the Hill of Stonyslacks, 8 km south of Buckie on Sheet 95 Elgin, and the Moss of Fishrie, on Old Red Sandstone sandstones and shales between Gardenstown and New Byth, on Sheet 96E Banff. Small spreads occur on Bracklamore and Windyheads hills to the south of Pennan, on Sheet 97 Fraserburgh, which are formed of Old Red Sandstone breccias and conglomerates.

Glacial and glaciofluvial features and the distribution of tills in the Elgin district. P915371.

Blanket hill peat is also widespread on the relatively high ground of central Buchan formed by the ‘Buchan Ridge’ and the Hill of Longhaven, which lie to the south-west of Peterhead (P915377). This ground is either underlain by the clayey, kaolinitic deposits of the Buchan Gravels Formation, or on bedrock that has commonly decomposed to sandy kaolinitic clay.

Correlation of lithostratigraphical units in north-east Scotland. P915347.

Woody peat deposits probably developed extensively around the coasts of north-east Scotland in the early to mid-Holocene, prior to the ‘Main Postglacial’ marine transgression, when most were destroyed by coastal erosion. However, some deposits have survived in sheltered situations, such as beneath the alluvium of the Water of Philorth, 3 km southeast of Fraserburgh (P915374; Philorth valley). Remnants of this so-called Boreal forest are exposed on the foreshore in Burghead Bay at low tide (P915371). Remnants of older peat deposits formed during the Windermere Interstadial are more sparse (P915347; table below; Rothens, Mill of Dyce, Loch of Park, Glenbervie, Howe of Byth). Deposits of early Devensian age or older are even rarer (Crossbrae, Moss of Cruden, Burn of Benholm).

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

Shell marl[edit]

Glacial and glaciofluvial features and the distribution of tills in the Elgin district. P915371.

Thin, discontinuous spreads of freshwater shell marl interbedded with basin peat and fluviatile silt overlie raised marine deposits around Loch Spynie, 4 km north-north-east of Elgin (P915371)). A 35 cm-thick bed of shell marl resting on Late-glacial marine clay was formerly visible in a brick pit situated in another alluvial depression at Gilston (NJ 206 662), nearby.

References[edit]

Full reference list