The Cleveland Dyke formed around an estimated 59 million years ago when hot magma forced its way through layers of sedimentary rock before cooling to form a hard igneous rock known as whinstone. This harder stone formed a ridge as the surrounding land was subsequently lowered by glacial action and the shape of this ridge can clearly be seen at Cliff Rigg Quarry.
Quarrying activity began in 1869 with huge quantities of whinstone being removed to provide high quality setts and road aggregates for the rapidly expanding city of Leeds. As a result of the quarrying Cliff Rigg Quarry today appears as a steep sided valley. The exposures left by the quarrying show the Cleveland dyke in full cross section and this has earned the area Site of Special Scientific Interest (SSSI) status due to its geological importance.