Sherwood Sandstone Group

Outcrop of Nottingham Castle Sandstone Formation in Park Tunnel, Nottingham.

The Sherwood Sandstone Group, formerly known as the Bunter Sandstone, predominantly comprises sandstone and pebbly sandstone with lesser amounts of conglomerate and minor amounts of mudstone and siltstone. It was deposited between 230 and 260 million years ago in the late Permian and Triassic periods.

It is present in several different sedimentary basins in the UK, including the Carlisle, Cheshire and West Lancashire, Worcester, East Yorkshire and Lincolnshire and Wessex basins. The thickness of the deposits vary considerably, from as little as 90 m in South Nottinghamshire to over 600 m in Lancashire.

Variable weathering of outcrops near surface and deeper dissolution of the cement binding the sand-sized grains has occurred in a number of places. As a consequence, the Sherwood Sandstone may occur as a dense sand or extremely weak sandstone, often to depths of several tens of metres.

The BGS is currently undertaking both macro-scale and micro-scale studies of the Sherwood Sandstone Group. Macro-scale studies are using ground-based laser scanning technology (LiDAR) to characterise the discontinuities present in the overall rock mass. Micro-scale studies utilise state-of-the-art laboratory equipment to characterise the physical properties and mechanical behaviour of samples of Sherwood Sandstone obtained from outcrops and boreholes. This includes properties such as uniaxial compressive strength, Poisson's ratio, Young's Modulus and compression and shear wave velocity.


Outcrop locations of Sherwood Sandstone Group.
Uniaxial (unconfined) compression test; shows the relationship between applied stress and strain for a sample of Sherwood Sandstone.
Preliminary results show a good correlation between effective porosity and uniaxial compressive strength for Sherwood Sandstone.

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Contact Marcus Dobbs for more information