57 million years ago Europe, North America and Asia were locked together in a great continent called Laurasis. Volcanic activity near what is now the Island of Mull in Scotland cause injections of magma deep underground in what geologists call the Mull Dyke Swarm. The magma cooled and formed a vertical dyke of hard igneous rock known as Whinstone. One such dyke outcrops in Cleveland where it is known as the Cleveland Dyke and on Cliff Ridge whinstone has been extensively quarried for use in road building. It is said that the streets of Leeds are cobbled with Great Ayton stone. In the 1880s Percy Winn took over the quarry from Leeds Corporation and is still referred to locally as Winn’s Quarry.
The photo shows the line of the dyke along Langbaurgh ridge heading towards Mull. Beyond Nunthorpe it goes underground but outcrops again at Preston Park on the north bank of the Tees and Cockfield Fell near Hamsterley. The word whin originates from the Old Scandinavian word for gorse, the prickly yellow flowered scrub which flourishes on the sides of the quarry.