49. A substantial thickness of Lambeth Group and Thanet Sand Formation (undifferentiated) and London Clay Formation overlie the chalk each estimated in excess of 10m thickness in most areas. The Crag Formations are also present from the coast to Tuddenham St Martin in varying thicknesses (circa 5-25m). The exception to this rule is within and around river basin areas, where the banks are cut down through the layers to the underlying chalk. The most exposed chalk areas are in the River Gipping valley around Claydon (Grid Ref: 61350, 24900) and Little Blakenham (Grid Ref: 61170, 24800) at the western end of the cable route. Figure 19.4 gives an example cross-section of these features.
50.
The presence of superficial deposits to the east of Great Bealings is sporadic and comprises mainly of the Kesgrave Catchment Subgroup directly over the Red Crag Formation.
51.
To the west of Great Bealings, Lowestoft Formation is present overlying the Kesgrave Catchment Subgroup and Red Crag Formation up to Tuddenham St Martin where the crag peters out and leaves the till directly above the Lambeth Group and Thanet Sand Formation (undifferentiated). The Lambeth Group and Thanet Sand Formation (undifferentiated) in turn peters out to the west of Claydon leaving the Lowestoft Formation directly overlying the Chalk Group.
19.5.1.4 Geological Designations 52.
The geology at the landfall is designated by Natural England as a Site of Special Scientific Interest (SSSI) and by the Joint Nature Conservation Committee (JNCC) under the Geological Conservation Review (GCR) record 593, known as Bawdsey Cliffs. The designation covers a 1-2km stretch of cliffs from the south of Bawdsey, near Bawdsey Hall, to the eastern side of the mouth of the Deben Estuary, near Bawdsey Manor Dairy and College. The cliffs are designated under Earth Heritage for their geological interest and provide one of the best and largest exposures of the Red Crag, showing its deposition and structure. Ground Investigation work carried out by RSK for East Anglia ONE identified that the structure of interest (Red Crag cliff) is absent from the footprint of the onshore electrical transmission works.
53.
Three GCR recorded sites, 602 Great Blakenham, 1758 Orfordness and Shingle Street and 2333 Waldringfield, border the edges of the study area. Two of these, 602 Great Blakenham and 2333 Waldringfield, are designated for their significance to the geomorphological evolution and Quaternary history of East Anglia. The other, 1758 Orfordness and Shingle Street, is categorised for its important coastal and fluvial geomorphology in terms of modern landforms and processes and large-scale mass- movement features. Further consideration of 1758 Orfordness and Shingle Street is undertaken in Chapter 7 Marine Geology, Oceanography and Physical Processes.
Preliminary Environmental Information May 2014
East Anglia THREE Offshore Windfarm
Chapter 19 Soils, Geology and Ground Condition Page 24
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