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Wednesday, 10 January 2024

An ice edge near Barnstaple?



I have been looking again at some old material relating to the glacial deposits around Fremington and Barnstaple, in Devon, and it is more and more apparent that there was a substantial glaciation in the valley of the River Taw, with an ice edge at least 15 km inland.

Good information is found in the following publication:

Quaternary deposits in the Lake Cutting of the Barnstaple Bypass, North Devon A.B. HAWKINS and S.C. HAWKINS, Proc of the Ussher Society, vol xx pp 301-303.

Research on the site of a new by-pass road revealed "pinky brown till" in the vicinity of Lake, some way to the east of the well-known glacial deposits at Fremington.  The designation of this deposit as "till" is well supported by sedimentological studies and field observations.  Indeed, the BGS map of the area conforms the presence of a sheet of till extending to the vicinity of Barnstaple, and clay (probably associated with both lacustrine and glacial deposits) is found at Bickington and Roundswell. 

There is another record in a local newspaper of a "porphyrite" boulde being found in 1920 at a Garden Centre in the district known as Newport, to the east of the River Taw.   There is no reason to doubt this, and indeed Nick Stephens, in various publications, recorded other erratics in the area.  Hawkins and Hawkins State "erratics of sandstone, quartzite, granite, tuff, dolerite, ?quartz-porphyry and andesite were reported by Dewey (1910) and Taylor (1956)."  Beneath the till there are layers of glaciofluvial gravel and lacustrine clay, which must be associated with the advance of an ice edge.


This of course all ties in with the presence of glacial erratics (including some high-level erratics) in the adjacent coastal zone including the Ilfracombe area -- and extending eastwards to include the deeply incised valleys of the North Devon coast and into Somerset least as far as Clevedon.

One glaciation, or several?  Work in progress..........





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