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Monday, 18 April 2016

Something for the record book


This has to be the most southerly exposure of coherent glacial deposits on land in the British Isles.  This silty and sandy till with faceted erratics and incorporating granite breccia and also some raised beach materials, is exposed near Long Point on the west side of St Agnes Island in the Isles of Scilly.

The grid reference is SV875078.  Lat: 49 deg and 88' North. Long: 6 deg and 35' W

There are erratics on the coasts of Wingletang Down, a bit further south, but they are from disaggregated earlier glacial deposits and are now scattered through raised beach and solifluction materials.  

So there we are, folks.  You saw it here first........

For the record, this is the stratigraphy:

Top -- c 1 m of dark organic-rich silts and sands topped with modern soil.  Partly windblown?
1m of light brown stratified silts and sands -- colluvium
Sharp junction
50 cms of mixed till with faceted erratics of grits, sandstones, shales and unknown volcanics.  Some cobbles of raised beach origin?
No sharp junction -- layers grade imperceptibly one into the other
About 2m of rotten granite debris / breccia / lower head with large angular granite clasts.
Base not seen -- masked by modern beach.
 

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