Kenn Church, Kenn Pier & Yew Tree Farm

Also within

Somerset County

Condition (Natural England)

Climate exposure

This is about exposure to a nationwide pressure this habitat type carries — not a verdict on this site's own management.

Geology & landscape

Geological Period: Quaternary

Landscape processes: Coastal, Glacial

Description

Description Temporary exposures in the Kenn area at Kenn Church, Kenn Pier Blind Yeo drain and Yew Tree Farm have shown a complex sequence of Pleistocene sediments. These include coarse glacial outwash gravels at the base overlain by a complex sequence of interglacial freshwater, estuarine and marine sands. The sequence is then capped by aeolian windblown coversands and Holocene silts. The interglacial sands contain a diverse molluscan fauna of a freshwater, estuarine and marine origin including the freshwater bivalve Corbicula fluminalis, the marine bivalve Macoma balthica and marine limpet Patella vulgata and also the terrestrial snail Vallonia enniensis. Amino acid dating of the mollusc shells has shown there to be two interglacial periods represented. At Kenn Pier and Yew Tree Farm an approximate date of 600,000 -700,000 years B. P. has been determined amino acid Stage at ma for the lower sands placing these sediments within the Cromerian Interglacial. At Kenn Church and Kenn Pier analysis of the upper sands has shown an approximate date of 120,000 -130,000 B. P. amino acid Stage II placing them within the Ipswichian Interglacial. The early age of the lower sands is particularly important as it indicates that the underlying basal glacial outwash gravels pre date the Cromerian glaciation providing evidence for the Pre Cromerian glaciation of the Kenn lowlands. The complex sequence of sediments in the Kenn area also provide clear evidence of the fluctuating sea levels within the Bristol Channel area during the Pleistocene. The presence of Cromerian Interglacial marine sediments at Kenn Pier and Yew Tree Farmindicates a contemporary sea level of 45 metres OD whilst at Kenn Church the Ipswichian rise in sea level reached 45 metres OD and possibly as much as 12 metres OD. Kenn Church also provides the unique opportunity within Britain to correlate amino acid dates for Ipswichian freshwater Corbicula and marine Patella molluscs within the same section.

Species mentioned