3.2.3 Geology
3.2.3.1 Overview The solid geology of the area around the project
is principally chalk, predominantly
overlain by superficial deposits of London Clay and outcrops of Red Crag deposits towards the coastal areas. In some areas, glacial sands and gravels are present above the clay. The Bawdsey Cliffs Site of Special Scientific Interest (SSSI), as shown on Volume 6, Figure 20.2 in the landfall area, is designated specifically for its geological interest.
No areas of worked ground, made ground, infilled ground or landscaped ground are indicated on the geological maps for the Preferred Onshore Cable Corridor or converter station.
There are no regionally important geological and geomorphological sites (RIGS) within the study area. Two sites listed as County Geodiversity Sites (CGS) have been indicated, but neither of these are close enough to the Preferred Onshore Cable Corridor or Converter Station Refined Area of Search to require further consideration.
3.2.3.2 Landfall
Superficial geology Geological mapping for this area shows that no superficial deposits are present close to the coastline.
Solid geology
The key issue of geological interest at the landfall is the Bawdsey Cliffs SSSI. This is located between Bawdsey Martello Tower and Bawdsey Manor and is a 2km section of early Pleistocene Red Crag deposits (see Volume 6, Figure 20.2).
The Red Crag formation comprises medium to coarse grained shelly sand, and is present unconformably overlying the Thames Group. The Thames Group deposits are up to 90m thick and are predominantly clay (including the London Clay).
Geological structure
The unconsolidated nature of the Red Crag units in this area is likely to mean that the coastline is vulnerable to erosion. Borehole records
Publically available borehole records available via the BGS website are available slightly north and south of the proposed landfall area. These indicate the presence of sand (thought to be derived from the Red Crag formation) overlying clay (London Clay). Table 2 provides additional details of each of the geological units.
3.2.3.3 Preferred Onshore Cable Corridor
Superficial geology The majority of the Preferred Onshore Cable Corridor is underlain by superficial deposits of some kind. However, superficial deposits are absent where bedrock units outcrop at
East Anglia Offshore Wind Limited
Preliminary Risk Assessment, East Anglia ONE Windfarm 41388-PRA(03)
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