OR/14/029 Modelled surfaces/volumes: Difference between revisions
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| | |+ Table 2. Bedrock units modelled in GSI3D-GOCAD | ||
| Lexicon code | | Lexicon code | ||
| Name | | Name |
Revision as of 11:41, 6 March 2015
Geological units modelled
In total, 64 superficial and artificial geological units were modelled (including mass movement deposits). Table 1 lists the units in broad stratigraphic order together with the BGS stratigraphic lexicon code for each (see https://www.bgs.ac.uk/lexicon/) and lithology. Standard BGS map colours have been used for all superficial units in the model (Figure 2). These should be referred to when viewing images of the model in this report. Note that the Head and Clay-with-flints deposits are known to be polycyclic, and in the case of the latter, its formation is likely to have started as early as the Pliocene.
Inferred age | LEXICON CODE | Full name | Lithology |
Holocene deposits and artificially modified ground | slip | Landslide deposits | Mass movement deposits; variable composition, dependent on the nature of the upslope material |
wgr | Worked Ground | Artificially lowered area, or void, through man-made excavation, e.g. a gravel pit | |
mgr | Made Ground | Artificially raised areas, variable composition | |
wmgr | Worked & Made Ground | Area of artificial cut and fill, e.g. a backfilled quarry, variable composition | |
ddgr | Disturbed Ground | Area of disturbance associated with surface or near-surface collapse | |
lsgr | Landscaped Ground | Extensively remodelled areas where it is difficult to delineate zones of Made, Worked or Disturbed Ground. Variable composition | |
peat | Peat | Humic deposits, consisting of wet dark brown partially decomposed vegetation | |
tufa | Tufa | Inorganic calcium carbonate or sinter deposited at or near springs and seepages | |
alv | Alluvium | Fluvial deposits of modern flood plains, consisting of clay, silt, sand and peat | |
Late Anglian – Devensian glacigenic deposits and river terraces, various catchments | rtdu | River Terrace Deposits (undifferentiated) | Sand and gravel deposits directly beneath alluvium |
head | Head | Solifluction or hillwash deposit, composition dependent on source material. Usually gravelly sandy clay | |
cwf | Clay-with-flints Formation | Residual deposit formed through weathering of a previous cover of Palaeogene deposits, and through dissolution of Chalk bedrock. Typically orange-brown and red-brown sandy clay with flint nodules and pebbles | |
rtdo | Pleistocene River Terrace Deposits (unclassified) | Exposed river terrace deposits (not below alluvium). Composed of sand and gravel | |
igd | Interglacial Deposits | Composed of silty clay | |
lasi | Langley Silt Member | Varies from silt to clay, usually yellow brown and massively bedded | |
shgr | Shepperton Gravel Member | Gravel with clay and sand | |
no1a | Northmoor Sand and Gravel Member | Sand and gravel | |
no1b | |||
no | |||
rosi | Roding Silt Member | Varies from silt to clay, usually yellow brown and massively bedded | |
esi | Enfield Silt Member | Varies from silt to clay, usually yellow brown and massively bedded | |
cfsi | Crayford Silt Member | Varies from silt to clay, usually yellow brown, often contains wind-blown sand | |
kpgr | Kempton Park Gravel Member | Sand and gravel, with local lenses of silt, clay or peat | |
bggr | Beenham Grange Gravel Member | Sandy clayey gravel | |
sura | Summertown-Radley Sand and Gravel Member | Sand and gravel | |
rtd2 | 2nd river terrace deposit | Sand and gravel | |
ilsi | Ilford Silt Member | Sandy clay and silt | |
tpgr | Taplow Gravel Member | Sand and gravel, locally with lenses of silt, clay or peat | |
thgr | Thatcham Gravel Member | Sandy clayey gravel | |
wv | Wolvercote Sand and Gravel Member | Sand and gravel | |
rtd3 | 3rd river terrace | Sand and gravel | |
hagr | Hackney Gravel Member | Sand and gravel, locally with lenses of silt, clay or peat | |
lhgr | Lynch Hill Gravel Member | Sand and gravel, locally with lenses of silt, clay or peat | |
han | Hanborough Gravel Member | Sand and gravel | |
rtd4 | 4th river terrace deposits | Sand and gravel | |
dasi | Dartford Silt Member | Varies from silt to clay, usually yellow brown, often contains wind-blown sand | |
figr | Finsbury Gravel Member | Sand and gravel, locally with lenses of silt, clay or peat | |
bht | Boyn Hill Gravel Member | Sand and gravel with possible lenses of silt, clay or peat | |
rtd5 | 5th river terrace deposits | Sand and gravel | |
bpgr | Black Park Gravel Member | Sand and gravel with possible lenses of silt, clay or peat | |
rtd6 | 6th river terrace deposit | Sand and gravel | |
sigr | Silchester Gravel Member | Clayey, sandy gravel | |
Anglian glaciation | loft | Lowestoft Formation | Till containing chalk and flint clasts |
gfdu | Glaciofluvial deposits | Sand and gravel | |
gstc | Glacial silts and clays | Composed of silt and clay | |
Pre- and Early Anglian terraces, various catchments | wihg | Winter Hill Gravel Member | Clayey, sandy gravel |
dhgr | Dollis Hill Gravel Member | Sandy, clayey gravel, with some laminated silty beds and local silt, clay or peat lenses | |
wogr | Woodford Gravel Member | Sand and gravel, locally with lenses of silt, clay, or peat and organic material | |
rtd7 | 7th river terrace deposits | Sand and gravel | |
bsgr | Beenham Stocks Gravel Member | Clayey, sandy gravel | |
wlgr | Westmill Gravel Member | Gravel and sand, with local lenses of silt, clay or peat and organic material | |
gcgr | Gerrards Cross Gravel Member | Gravel and sand, with local lenses of silt, clay or peat and organic material | |
bygr | Bucklebury Common Gravel Member | Clayey, sandy gravel | |
swgr | Satwell Gravel Member | Sand and gravel | |
rtd8 | 8th river terrace deposit | Sand and gravel | |
stgr | Stanmore Gravel Formation | Flint-dominated gravel with a clay and sandy clay matrix | |
whgr | Well Hill Gravel Formation | Gravel and sandy gravel | |
cwgr | Chorleywood Gravel Member | Sand and gravel | |
cagr | Cold Ash Gravel Member | Sand and gravel | |
bdgr | Beaconsfield Gravel Member | Sand and gravel | |
suhg | Surrey Hill Gravel Member | Flint-dominated gravel | |
chgr | Chelsfield Gravel Formation | Sandy flint-dominated gravel | |
wggr | Westland Green Gravel Member | Sandy, clayey gravel | |
sgao | Sand and gravel of uncertain age and origin | Sand and gravel |
In addition 12 bedrock units (Tables 2 and 3) were included in the cross-sections and their distributions (envelopes or coverages) modelled in GSI3D, some of these units are faulted and the faults were also defined in the cross-sections. These data were then exported to GOCAD® for calculation of full faulted surfaces to complete the bedrock part of the model. The list of modelled bedrock units is given at Table 2 whilst their relationships and stratigraphic hierarchy is at Table 3.
Lexicon code | Name |
LNM | Lenham Formation |
CMBS | Camberley Sand Formation |
STHP | Stanners Hill Pebble Bed |
WIDS | Windlesham Formation |
SAHP | St Ann's Hill Pebble Bed |
SWCL | Swinley Clay Member |
BGS | Bagshot Formation |
CLGB | Claygate Member |
LC | London Clay Formation |
HWH | Harwich Formation |
LMBE | Lambeth Group |
TAB | Thanet Formation |