Grafham Plateau

The Grafham Plateau forms a northwest-southeast aligned dissected ridge reaching above 70m OD between the Nene valley and the Great Ouse valley. It has a significant thickness of Oadby Glacial Till overlying the Oxford Clay bedrock. Under the village of Catworth there is a large piece of Chalk (a Chalk raft), which was broken off from the Chalk bedrock far to the east and brought here by ice, probably during the Anglian Glaciation about 425,000 years ago. There are also patches of Glacio-fluvial and River Terrace Deposits, mostly on the edges of the Plateau or in the vallley of the River Kym. The Glacial Till and bedrock clay produce heavy, poorly drained soils whilst there are well-drained soils on the Glacio-fluvial and Terrace gravels. There are no geological SSSI or LGS.