OR/13/001 Modelled surfaces/volumes

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Geological units in the model are as follows:

mgr Made ground
wgr Worked ground
wmgr Worked and made ground
stobco Shoreface and beach upper layer (along coast)
alv Main Freshwater Alluvium
itdu Intertidal Deposits undifferentiated
stob Shoreface and beach deposits lower layer
isc Interglacial silt and clay
head1 Head (silt reworked loess?)
brk Brickearth (local overbank deposits on terraces)
rtdu River Terrace Deposits undifferentiated
lde1 Lacustrine deposits (Clacton and Marks Tey)
gstc Glacial Silt and Clay supramain till
gsg Glacial Sand and Gravel supramain till
loft Lowestoft Till (main sheet)
gstcb1 Glacial Silt and Clay below till 1
gsgb1 Glacial Sand and Gravel below till 1
gcd Glacial Channel deposits
igd Interglacial deposits (Little Oakley)
kes Kesgrave Sand and Gravel
rcg Red Crag Formation
tham Thames Group
llte Lower London Tertiaries
ck Chalk Group undiff
glt Gault Formation
gsg1t Glacial Sand and Gravel in main till sheet (top)
gsg1 Glacial Sand and Gravel in main till sheet (base)

The sequence shares a common *.gvs with the adjacent Ipswich-Sudbury area model.

Multiple layers of storm beach deposits were needed to cope with interdigitated sequences and Holocene evolution. The Anglian glacigenic sediments shown above in blue comprise the Lowestoft Formation and within them a single lens is identified (gsg1). Legend colours in many cases loosely correspond to the 50K published map sheets. The difficulty in separating the thin Thanet Sand Formation from the Reading Formation (Lambeth Group) has resulted in the use of the older Lower London Tertiaries term being used for this package of strata. The Harwich and London Clay Formations cannot be mapped out separately and are lumped together as the Thames Group.

The model abuts the Ipswich-Sudbury model to the north (Mathers, 2012[1]), shared docker sections ensure a common interpretation along the join at northing 30.


  1. MATHERS, S J. 2012. Model metadata summary report for the Ipswich-Sudbury LithoFrame 10-50 model. British Geological Survey Open Report OR/12/080.