Look closely at the photograph above and you will see shallow grooves running across the surface of the rock at a slight diagonal from top to bottom of the image. These scoring marks cut across the strata of the rock which lie approximately horizontally from left to right in the image. The surface of the rock has also been smoothed off, polished even, so that there are no protruding lumps and bumps. The grooves, parallel cuts, or score marks are known as striations and result from glaciation.
A striation is a narrow groove or scratch cut in exposed rock by the abrasive action of hard rock fragments embedded in the base of a sliding glacier. Striation provides a useful clue to the direction of ice movement in formerly glaciated areas (Oxford Dictionary of Earth Sciences, Ed. Michael Allaby, Oxford University Press, 2008, ISBN 978-0-19-921194-4).
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