TORRIDONIAN SANDSTONE - 1 billion years old - Stac Pollaidh (Stac Polly), Scotland
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Approx. 1 billion years old
Stac Pollaidh (Stac Polly), Northwest Highlands, Scotland
In the north-west of Scotland there are very ancient crystalline rocks known as Lewisian Gneiss. When this gneiss was formed only simple single-celled life forms existed in the oceans. On top of this gneiss is the Torridonian Sandstone which is brown in colour from oxidised iron - an indication that oxygen was being released by early organisms into the oceans.
The UK was at this time split into two with Scotland and Northern Ireland attached to North America and the rest of Britain attached to Europe, with a wide ocean in between. The two continents were situated south of the equator.
Stac Pollaidh (Stac Polly) is a mountain with a rocky crest of Torridonian sandstone. The sandstone contains numerous pebbles and is derived from erosion of the gneiss. It contains not only quartz but also feldspar and is more accurately known as arkose.
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Size: approx.13.5 x 8 x 3.5 centimetres
Weight: 542 grams
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