Wider significance

The Fell Sandstone is one of the most prominent and best-exposed rock units in the Carboniferous succession of the Northumberland Trough. Sedimentary features typical of fluviodeltaic alluvial plain sediments, with braided and meandering river bedforms are outstandingly displayed in the crags. The river system, flowing some 340 to 330 million years ago, may have been comparable in extent to the braided stretches of the modern Brahmaputra River in Bangladesh. The high quality of the sections has continued to invite a number of modern detailed interpretations of such depositional environments and sedimentology.

The Fell Sandstone is associated with a variety of prehistoric sites, which together form some of the most interesting archaeological landscapes in England. These include ‘cup and ring’ marked rocks, Bronze Age burial cists, earthwork remains of later Iron Age hill fort systems, standing stones, enclosures, and cairns.

Geological SSSI

Dinantian of northern England and North Wales:

• Colour Heugh and Bowden Doors [NU 066 337 to NU 070 326]

Geological SNCIs

Akenshaw Burn, Bowden Doors, Callaly and Thrunton Crags, Catcleugh Burn, Coldmartin Loughs, Dovecrag Burn, Kyloe Hills, Shiellow Crags, Thrum Mill Gorge, NWT reserves Harbottle Crags.