Millook
Millook is a place on the north coast of Cornwall. It has these remarkable cliffs.[1] The cliffs at Millook are so famous they were voted by the Geological Society as one of Britain's top 10 geological sites. They came top of the "folding and faulting" category.[2]
The cliffs have a series of horizontal chevron folds. The rocks were once sedimentary rocks laid down in deep water during the Devonian and Carboniferous periods. We know this because they still contain brachiopod fossils of a type which lived in the late Devonian period. Later they were altered by heat from granite during mountain building in the English counties of Devon and Cornwall.[3]
The Variscan orogeny caused the intrusion of the hot granite. The subsequent contact with the sandstones created the metamorphic rocks seen today. This also put intense pressure on the sediments causing them to be folded and faulted. What we see is a small part of a huge mountain system caused by a continental collision between Euramerica (Laurussia) and Gondwana. This formed the supercontinent of Pangaea.
References[change | change source]
- ↑ Ordnance Survey: Landranger map sheet 190 Bude & Clovelly (Map). Ordnance Survey. ISBN 978-0-319-23145-6.
- ↑ Jonathan Webb (13 October 2014). "Chart-topping rocks: UK's 'Greatest Geosites' announced". BBC. Retrieved 13 October 2014.
- ↑ Inter-bedded sandstones and shales were originally deposited in deep water: Bastida F.; Aller J.; Toimil N.C.; Lisle R.J.; Bobillo-Ares N.C. (2007). "Some considerations on the kinematics of chevron folds". Journal of Structural Geology. 29 (7): 1185–1200. Bibcode:2007JSG....29.1185B. doi:10.1016/j.jsg.2007.03.010.