An TealachWhile the surface aspect of the scene has been carved by ice in the glaciations of the las

An TealachWhile the surface aspect of the scene has been carved by ice in the glaciations of the last two million years, the underlying rocks forming what has been called Scotland’s most beautiful peak are alot more ancient. The name comes from the Gaelic for ‘the forge’, because the dominant rock is a red sandstone that glows in the sun, topped by a white Cambrian quartzite. There are three main red sandstones in British Geology, this one known as Torridonian, laid down before Scotland collided with England and Wales as the Iapetus ocean closed roughly a billion years ago, and higher up in the sequence the much younger old and new red sandstones, testimony to the Silurian to Devonian erosion of the Caledonian mountains and the later inland deserts of Pangaea during the Permian.The Torridonian rocks date from the precambrian, and were deposited over some of the oldest rocks in the Isles, the Lewissian gneiss before being covered in turn by the Cambrian quartzite around 500 million years ago. I’m told that despite their great age, sedimentary structures are preserved as if they were laid down last year. They mark a major boundary between terranes, and are also associated with the Moine thrust, a fault that pushed the Lewissian Gneiss over the younger rocks during a continental collision and mountain building event before Pangaea was formed. The thrust is also a benchmark in the history of geology. Since hard highly metamorphosed rocks sat atop obviously younger intact sedimentary ones, the thrust provided some of the first inklings of the enormous forces that shape our planet. The peak is complex with over ten different summits over 900 metres, and surrounded by moraines left behind by the retreating glaciers.LozImage credit: Dougie Cunninghamjncc.defra.gov.uk/pdf/gcrdb/GCRsiteaccount174.pdfhttp://www.see.leeds.ac.uk/structure/mtb/southernzone/teallach/http://www.see.leeds.ac.uk/structure/assyntgeology/extra_info/walk/ -- source link

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