OR/13/001 Modelled surfaces/volumes

Geological units in the model are as follows:

CODE NAME
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
BEDROCK
rcg	Red Crag Formation
tham	Thames Group
llte	Lower London Tertiaries
ck	Chalk Group undiff
glt	Gault Formation
LENS
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), shared docker sections ensure a common interpretation along the join at northing 30.