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Monday, 20 July 2026

West Angle Quaternary exposures

 


This is a nice oblique aerial photo of West Angle Bay, taken fairly recently by a drone camera.  The rocky embayments in the middle and left foreground hold a number of exposures of  Late Devensian (LGM) till and periglacial deposits.  The main bay, right of centre, holds one of the most important Quaternary sequences in Wales.  Between the sandy beach and the big caravan park there used to be a brick pit -- now largely destroyed, partly infilled with rubble.  On the seaward edge of this brick pit there was a wonderful exposure of Quaternary sediments, including last Interglacial (Eemian / Ipswichian) silts, clays and peaty beds, and a sequence of glaciasl and periglacial sediments related to the LGM ice advance across western Pembrokeshire.

We get a nice impression from this photo of the quiet estuarine environment that must have existed in this embayment and through valley during the last interglacial.

I have multiple posts about this site, concentrating on the controversy of the Pre-Ipswichian glacial deposit.  DQ Bowen and others claim to have seen it, and so the site has been used by BGS as a "type locality" for the Penfro Till formation.  This is a huge mistake, perpetrated to this day in the literature.  Dave Unwin and I are the only two people to have excavated this site properly, and we found no trace of any till beneath the raised beach.  Other casual observers at this site have failed to recognize the extent to which glacial tectonics have redistributed slabs of sediment. Bits and pieces of peat beds and interglacial sediments have been detasched and thrust over parts of the Devensian glacial sequence, in effect inverting the key layers.  See my posts for further information:


https://www.blogger.com/blog/post/edit/1228690739485734684/1824604806378202597


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