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Friday, 7 August 2015

Rhyolite erratics from Devon


 These boulders (some of them are made of local foliated rhyolite) have not travelled far.  In fact, they are still at Rhosyfelin, rounded by ice and water to varying degrees.  Wouldn't it be interesting if some similar boulders had been transported to the coast of Devon?

A reminder of this post, and of the work of Paul Madgett and others in Devon, revealing the presence of rather a lot of erratic boulders in places where they could not have been transported by ice floes..........

http://brian-mountainman.blogspot.co.uk/2015/01/croyde-saunton-baggy-point-erratics-list.html

Here is a part of Paul's list of erratics from the Croyde area:


Note that there are several boulders of "rhyolitic tuff" in this list, namely numbers 10, 19, and 37, with others described as rhyolite (31) or tuff (13, 20 and 33).  Sometimes it is difficult to classify a rock type simply from examining the weathered surface of a rounded boulder -- but wouldn't it be interesting if one or two of these -- or maybe even more -- should turn out to be made of foliated rhyolite from Rhosyfelin? 

We need some samples -- but I would not be at all surprised if rhyolite boulders and fragments from the Rhosyfelin - Pont Saeson area had been transported by Anglian ice into Devon and Somerset.

1 comment:

TonyH said...

"We need some samples - but I would not be at all surprised if rhyolite boulders and fragments from the Rhosyfelin - Pont Saeson area had been transported by Anglian ice into Devon and Somerset."

Regarding Somerset, perhaps Stephen Rippon's book, "Landscape Community and Colonisation: the North Somerset Levels During The 1st to 2nd Millenia A.D.", ISBN 9781902771670, price £38, now available at £19 from Oxbow Books, Oxford, may help in the search.

In any event, it could be useful with respect to the broader search for Erratic rocks in N Somerset -there have been previous posts on this topic.