Our Geology

The South Pennines form part of the Pennine ‘backbone’ of England. This narrow range of hills, over 2,000 feet at the highest point, stretches 250 miles from the Peak District of Derbyshire to the Scottish border.

Millions of years ago, when river deltas covered this part of Britain, grit, sand and silt were washed down and deposited here. These became the gritstones, sandstones and shales of the South Pennines. As the conditions changed, these layers were covered by other sediments – forming rocks such as coal.

The Pennines formed in a great upheaval of the rocks, caused by a distant collision of continents. After the uplift, the land may have been as high as the Alps are today! But the softer rocks on top of the Pennine dome were gradually eroded away – once again exposing the harder gritstones beneath.

During successive Ice Ages, great glaciers gouged out wide valleys. As the ice retreated, meltwater torrents continued to deepen some valleys dramatically, leaving side streams to cut their way down steeply to the new valley base below. This abundance of powerful, fast-flowing stream water has had a profound impact on the industrial development of the area.

The South Pennines’ own Millstone Grit and the deposits of limestone left behind by the glaciers have also helped to shape the area’s traditional buildings and industries. They have provided stone to build local farms, homes and mills; rocks to build characteristic drystone walls; and limestone for the production of lime in kilns for use as fertilizer.