47. A summary of the bedrock geology formations, their descriptions and likely thickness is provided in Table 19.10 below and in Figure 19.3.


Table 19.10 Summary of Underlying Bedrock Geology4 Stratum


Age Description Red Crag Formation


Tertiary, Pliocene


Sand, medium to coarse grained, shelly in lower parts, strongly iron stained at surface, green at depth. Basal beds rich in phosphate pebbles. Horizontal planar bedding indicative of a shallowing basin.


Coralline Crag Formation


Solid


Thames Group


London Clay Formation


Harwich Formation


Lambeth Group and Thanet Sand Formation (undifferentiated)


Chalk Group


Culver Chalk Formation


Newhaven Chalk Formation


19.5.1.3 Geological Structure 48.


Tertiary, Pliocene


Tertiary, Eocene


Tertiary, Eocene


Tertiary, Palaeocene


Upper Cretaceous


Upper Cretaceous


Calcrenite (sand), yellow- brown at surface, green at depth, shelly, partly indurated


Clay, blue-grey, variably silty with thin sand and pebble beds


Clay, silty with ash layers and cementstone nodules and beds


Clay, sand and silt, mottled colour, with a thin flint pebble bed at the base


Chalk, white, soft, with flint nodules.


Chalk, white, marl, flint free beds.


Thickness


0 to 31m (absent to the west)


0 to 22m


0 to 20m 0 to 20m 0 to 19m


0 to 10m


circa 50m


Chalk Group 200m+


At depth the Chalk Group dips gently to the east; sitting approximately 50m below ordnance datum (BOD) at the coast and nearing or at surface level around Claydon. Consequently the overlying formations thin towards the west.


4 After BGS solid and drift geology sheets 207, 208, 225 and British Regional Geology, East Anglia and Adjoining areas


Preliminary Environmental Information May 2014


East Anglia THREE Offshore Windfarm


Chapter 19 Soils, Geology and Ground Condition Page 23


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