Geology Site Account

Site name: Orsett Depot Quarry (also called Orsett Camp Quarry)

Grid reference: TQ656809

Summary of geological interest

Former sand and gravel pit with previous exposures of the Upnor Formation. Pit now largely infilled and sections obscured.

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Site description

To the south of Orsett Cock Quarry is Orsett Depot Quarry, a large, disused sand and gravel pit formerly providing excellent exposures. The faces originally revealed layers of sand and gravel which are a literally a cross section through a sea floor some 55 million years old.

The pale yellow sand and layers of well-rounded black flint pebbles are part of the Upnor Formation (formerly known as the Woolwich Bottom Bed) and are thought to have been deposited close to a shore line and show evidence of being pounded together under storm conditions. In some places the sand reveals fossilised burrows of marine animals such as shrimps that inhabited this ancient sea. The junction of the Upnor Formation with the underlying Thanet Sand was formerly visible at the base of the section (the junction was conspicuous due to water seepage).

At the top of the section Thames terrace gravel of Pleistocene age could formerly be seen. These Thames gravels are Orsett Heath Gravel and therefore the oldest and highest of the Thames Terraces.

The quarry is private land and access is only available with the prior permission of the land-owner.

Orsett Depot Quarry (West Pit) in 1973. Photo © British Geological Survey P211783