Geology Site Account

Site name: Coombe Green Sand Pit (disused), Great Warley.

Grid reference: TQ 5766 9045

Brief description of site:

Just south of Stonyhills Farm, Great Warley is a triangular wood bounded by three lanes. In it is a shallow, overgrown sand pit which has a very small exposure of typically fine-grained Bagshot Sand. Exposures of Bagshot Sand are extremely rare in Essex.

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Details

Bagshot Sand is as a result of the gradual shallowing of the London Clay Sea about 50 million years ago. The sediment being deposited on the subtropical sea floor started as a mud that we now know as London Clay and became more and more sandy until eventually it consisted entirely of the fine yellow sand we now call Bagshot Sand. This sand was probably laid down across most of Essex in a great complex of river deltas and all that now remains of it are isolated patches on the tops of these hills in south Essex, the rest having been removed by the intense erosion of the Ice Age.

This pit is shown on the OS map of 1920 and was visited by the Geologists Association in 1915 (Boswell 1915).