the landfall, and at several locations between Falkenham and Playford. Small outcrops of bedrock are present close to the River Gipping.
Superficial deposits present between the landfall and Falkenham are mud deposits formed in tidal flats, channels and saltmarshes. Glaciofluvial sands and gravels from the Kesgrave Formation are extensive between Kirton and Martlesham, and occur sporadically in smaller areas between Martlesham Creek and the converter station.
River terrace deposits are present around Martlesham Creek and the River Gipping. Boulder clay is encountered extensively across the western end of
the route, from
Playford to the converter station. Small areas of alluvium are present around the River Gipping and close to the watercourse near Larks Hill. Further details of all the superficial units are provided in Table 2.
Solid geology As mentioned in the landfall section,
the Red Crag formation is present outcropping
along the coast. Further inland the Thames Group is found, underlying marine and tidal flat deposits around the River Deben, and at outcrop around Falkenham. Further outcrops of Red Crag are shown on mapping north of Falkenham, recurring intermittently as the route continues northwards parallel to the River Deben. London Clay deposits are present at the surface in a small number of locations, generally along the line of watercourses (Kirton Creek and Martlesham Creek), and are present below the superficial deposits for much of the western end of the route. Chalk Group deposits are present around the River Gipping, outcropping for small areas on both sides. There is some presence of Lambeth Group and Thanet Sand Formation deposits beneath superficial deposits near Akenham and around the converter station area. Subcrops of the Red Crag Formation are also noted around Tuddenham St Martin and south of Little Blakenham.
Geological structure
The geological structure of the area is typified by roughly horizontal beds of the various bedrock units (a slight dip towards the east is present). Unconformities are present between units from the differing depositional periods. (An unconformity is a change in rock sequence indicating a break in sedimentation, commonly accompanied by erosion of rocks below the break). River channels cutting through the bedrock units are common. No folding or faulting of units is noted on the geological mapping for this area.
Boreholes
One borehole is located just on the western bank of River Deben (grid reference 32080 38390). Clay was present from the surface to 9.4m below ground level (bgl). The clay was shelly near the surface, with increasing quantities of organic material at greater depth. Sand deposits containing gravel and flints was present borehole at 10m.
to the base of the
A borehole record located close to the sewage works between Kirton and Falkenham (29270 39360) indicates topsoil over clay to 2m bgl. Fine grained red brown shelly sand is encountered to nearly 8m bgl (Red Crag), below which London Clay is proved to 9.1m.
East Anglia Offshore Wind Limited
Preliminary Risk Assessment, East Anglia ONE Windfarm 41388-PRA(03)
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