II. On some supposed Ice-scratches in Derbyshire

Abstract

In the number of the GeologicalMagazine for last August, in a letter from Mr. Mackintosh, there is a notice of some markings, supposed to be glacial, on a rock known as ‘The Bloody Stone’, between Cromford and Bonsall, in Derbyshire. Mr. Mackintosh's language is not very clear, but I rather gather that he has doubts whether these markings were really made by ice: nor does he seem to be aware of the great interest that would attach to the discovery, if it could be proved beyond question that we have here a true ice-marked surface of rock. It is, I believe, very generally the case that the deposits and, so to speak, footmarks of the Glacial epoch are found on the western side of the central axis of the north of England in much greater force than on the eastern side. Thus much I can say from personal observation: in North Staffordshire and Lancashire, boulder-clays and gravels are found stretching from the plains far up the hill-sides, and erratic blocks lie here and there upon the moors to a height of 1,400 feet above the sea. On the other side of the socalled Pennine Chain, however, the case is widely different: through-out the whole of North Derbyshire and the adjoining uplands of Yorkshire there is nothing that can be safely set down as Drift, and certainly no blocks or pebbles of foreign rocks over the country to the north of the Wye. The valley of that river cuts right across the Great Saddle; and along it, and to the south of it, we do find stray patches of clay with ice-scratched boulders, mostly of limestone, but here and there of granite, greenstone, and other strangers, which seem to have found their way from the west along this sole opening in the barrier which elsewhere blocked up their path. ‘The Bloody Stone’ is just a case in point, lying as it does in the valley of the Derwent, about seven miles below the junction of the Wye with thatriver. I was, therefore, extremely glad to see Mr. Mackintosh's letter just in time to pay a visit to the spot, and I shall tell as carefully as I can what I there saw, in hopes that more experienced ice-men, if they cannot go to see for themselves, may be enabled to decide whether we can fairly refer the markings in question to the action of ice.