Durham Coast - Blackhall Rocks (SSSI)
Location and Access Information
Grid Reference: NZ 473387
The coastline between Seaham and Blackhall is accessible at a number of points, notably at Seaham in the north, Easington, Peterlee and Blackhall Rocks in the south. There is an extensive cycle network and 20km of coastal footpath. Further information on the natural and social history and interest of the coast as well as practical information on events and access can be found at:
Blackhall Rocks, south of Peterlee is a Durham Wildlife Trust reserve from where access to the beach and cliffs can be gained. The reserve can be approached from a number of points although the car park close to the rocks is the most convenient. From the crossroads on the A1086 at Blackhall Rocks Village, a minor road leads east under a railway bridge and down towards the beach. A right fork leads to a car park. There is a steep footpath down to the sea. Information about the reserve is available at:
View the site map on Nature on the Map
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Geological Interest
In the east of County Durham the plateau formed by the Permian (290-248 million years ago) aged Magnesian Limestone dips gently to the North Sea so that the rocks are exposed at the coastline. The Magnesian Limestone, so named because the rock contains the magnesium rich mineral 'dolomite' was deposited in a relatively shallow landlocked sea extending from northeast England to Poland, known as the Zechstein Sea.
The estimated average temperature during the period was approximately 23 degrees Centigrade. Due to the landlocked nature of the sea and high temperatures, deposits of gypsum and anhydrite (collectively known as evaporites) derived from evaporation of the seawater, are found throughout the rock sequence. Within the Magnesian Limestone sequence the remains of fossil reef structures formed by algae, brachiopods and bivalves can be found.
Good cliff and foreshore exposures can be seen at a number of places. At Blackhalls Rocks a number of spectacular dome-like structure can be seen in the dolomitic limestone exposed in the cliff and foreshore sections. These domes are complex growths of algae that formed through the trapping of fine mud by films of algae in the warm, shallow saline waters. Similar structures can be seen today at Shark Bay in Western Australia.
