In the article about Roseberry Topping, A Stroll with Stuart, 30 March, we are wrongly told that the Whin Sill occurs there.
‘You are now on the slopes of the Whin Sill.......’ Stuart tells us. This is completely wrong.
The igneous intrusion on the Great Ayton side of Rosberry Topping, exposed in a number of long abandoned trench-like quarries, is the Cleveland Dyke.
This is a vertical sheet of igneous rock which was intruded deep beneath the surface 58 million years ago.
It’s only similarity to the Whin Sill is that the two intrusions are made of dark coloured, though not identical rock.
The Sill occurs as a near horizontal igneous intrusion in Upper Teesdale and north to the coast at the Farne Islands and west to the the west-facing escarpment of the Pennines near Appleby.
The dolerite sill was intruded about 295 million years ago, and occurs nowhere near Great Ayton.
The new treatment for the lighthouse is excellent, perhaps aliens could help with the work!
Chris Pellant, Fat Ox Farm, Houlsyke by email