The Ramson Cliff erratic, about 80m above sea level. Since this photo was taken it has sunk more deeply into the undergrowth.......
As we dig deeper into the Quaternary history of the Bristol Channel region, the collection of (mostly igneous) erratics around Croyde and Saunton appear more and more important. As indicated by Keene and Cornford in their booklet called "The Cliffs of Saunton" and Madgett and Inglis (1987) there can be no doubt that the 50 or so erratics described in the literature represent the last remnants of an ancient glaciation. Some of the recorded erratics are quite small, but of the 37 larger erratic recorded in the tables below, there are a number (dolerite, rhyolite, rhyolitic tuff and other volcanics) that could have come from North Pembrokeshire, but the geologists who have looked at them prefer, at the moment, to suggest provenances in Scotland or other northern parts of the British Isles.
https://devonassoc.org.uk/wp-content/uploads/2018/11/A-Reappraisal-Madgett-TDA-1987.pdf
These erratics (including one at about 80m asl) must have been a part of a spread of glacial deposits; they cannot all have been dumped from grounded icebergs or ice floes since at times of cold climate seal level would have been many kilometres away from the present position of the coast.
The glacial episode responsible must also have affected (if not overrun) Lundy Island, and the other islands (including Flat Holm) further up the Bristol Channel. Even if the ice surface gradient was very shallow, ice at the same time must have penetrated eastwards past Ilfracombe, Lynmouth and Minehead, and into the Somerset Levels. It may well have impinged upon the west-facing chalk escarpment of Salisbury Plain. It may of course have coalesced with ice coming off an independent Exmoor ice cap. But in general, it may well be that the North Devon cliffline was the prominent landscape feature that resisted the flow of the Irish Sea Glacier and channelled it eastwards.
https://devonassoc.org.uk/wp-content/uploads/2018/11/A-Reappraisal-Madgett-TDA-1987.pdf
The Ramson Cliff erratic above the north-facing Ramson Cliff, near Morte Bay, about 150m inland and on the edge of the coastal slope.
About halfway along the north side of Baggy, there is another (smaller) glacial erratic sat right next to the path. It is a 500 kg block of epidiorite of Scottish origin. It is a little difficult to spot, as it is surrounded by gorse, and is slowly disappearing into the surface. Part of the surface has been chipped away, exposing the obvious crystalline structure of igneous rock. It once stood upright in the middle of a nearby pasture field and was used as rubbing post by sheep and cattle. In the early 1970s, the field was ploughed and the rock dislodged and then laid prone. It was then dragged to edge of field where it has been ever since. The erratic can be located at grid reference SS 4356 4070.
Dark coloured crystalline rock (epidiorite) adjacent to coastal footpath at c 80 m asl.
(Photo: Paul Berry)
2 comments:
See my Facebook Post just made about the National Trust coastline Walk, presumably passing Ramson Point.
Ramson cliff, not Point.
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