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Photographer's Note

Hi,

This image highlights the power of nature. How do you lift such a large bolder and place it down onto a plinth of three small limestone rocks?

This is one of a number of bolders that lie strewn across the hillside at a place called Norber, just above the village of Austwick in the North Yorkshire Dales.

Known in geology as an erratic, the explanation is that the large bolder, which is made from non-porus gritstone, was carried into the area on the underside of a glacier during the last ice age (only) some 8,000 years ago. When the glacier retreated, the gritstone was left resting on the limestone sedimentary rock, which is some 400million years old!. Over the years, wind and rain erosion has eaten away at the porus limestone that was beneath the bolder, leaving three rocks, which were more resilent that the limestone that surrounded them.

The result is an erractic. Harder gritstone resting on a plinth of limestone.

Taken today on a walk around Crummuck Dale, which is a lesser known Yorkshire Dale, which runs like a wedge North of Austwick. The Dale cuts deep into the limestone of the mid-Craven fault, and is surrounded on three sides by limestone escarpment and pavements.

I will post more tomorrow. Hope you like the shot.

John

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Additional Photos by John David (johnnymag) Silver Star Critiquer/Gold Note Writer [C: 40 W: 0 N: 111] (490)
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