Siccar Point - Hutton’s unconformity. EarthCache
turningstones: Thank you to everyone who found this - if anyone wants to take this one over please let me know
Siccar Point - Hutton’s unconformity.
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Hutton’s unconformity is known worldwide as a geological pilgrimage. It is an unconformity - an erosion surface separating two rock layers of different ages. The older layer was laid down and tilted and the surface eroded - worn away over time - before the younger rock was deposited above. The unconformity is the time when no sediments were preserved.
James Hutton came here and found the perfect site to show evidence to support the idea of plutonism (that rocks are formed from volcanic magma and continually eroded to sediments which are then deposited and reformed by heat and pressure into sedimentary rocks) and uniformitarianism “the present is the key to the past".
He visited in 1788 with fellow scientists John Playfair and Sir James Hall. Here is part of Playfair’s account;
“On us who saw these phenomenon for the first time the impression will not easily be forgotten...We felt necessarily carried back to a time when the schistus on which we stood was yet at the bottom of the sea, and when the sandstone before us was only beginning to be deposited, in the shape of sand or mud, from the waters of the supercontinent ocean... The mind seemed to grow giddy by looking so far back into the abyss of time; and whilst we listened with earnestness and admiration to the philosopher who was now unfolding to us the order and series of these wonderful events, we became sensible how much further reason may sometimes go than imagination may venture to follow.”
The coordinates are for the information sign on the headland above the section. It is approximately 1 mile from Pease Bay Caravan Park – the paths are now signposted. Hutton originally travelled the by sea. The slope down to the sea is difficult especially when wet – see the warnings on the information board. This cache is collected from the top of the cliffs.
There are some possible parking waypoints listed below. The first and closest is a layby, on the road to the Drysdales vegetable processing plant, from which the cache can be reached by walking around the field (N55° 55' 40.0008" W002° 18' 51.3936"). The second is a small public car park at the Pease Bay caravan site (55° 55' 44.0472" -2° 19' 50.8044"). From here you can follow the James Hutton Trail along the cliffs. There are facilities at the caravan park. There are public toilets on the A1 just north of the Cove junction (heading north). Both car parks use a route that passes the ruined St Helena's Chapel a Romanesque style church built of sandstone and greywacke.
There are 2 things to do to claim this cache:
1. Stand on the top of the slope and you can see the vertical greywacke beds with flat sandstone beds above (the layers are well explained on the sign). Draw a quick sketch diagram of the rocks – it doesn’t have to be an artistic masterpiece but do try and draw the rocks that you see. Include a scale bar, a title, and label what you see.
2. Answer 2 questions based on the information board;
a) The sign has a set of diagrams showing “how the unconformity was formed” – how many steps are there?
b) According to the sign how long ago did James Hutton visit the section?
Scan or photograph your sketch and post it on your log and message me the answers to the questions to claim this cache.
Permission to place this cache was kindly given by SNH and the Scottish Outdoor Access Code
Additional Hints
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