On the Junction of the Silurian Rocks and Carboniferous Limestone On
Downloaded from http://pygs.lyellcollection.org/ by guest on September 30, 2021 309 JUNCTION OF THE SILURIAN HOCKS WITH THE OVERLYING MOUNTAIN LIMESTONE, AT MOUGHTON FELL, IN RIBBL1S- DALE. BY THE EDITOR. (SEE PHOTOGRAPH.) THE photograph issued with this year's volume of proceedings, illustrates an important section exposed in the valley of the Bibble, nearly opposite the village of Horton. The Silurian rocks, composed of grits, slates and limestones, extend over a large area, bounded by the line of the Pennine Fault, running in a north and south direction, and that of the equally important series of Craven Faults which run eastward from Ingleton, their position being indicated by the precipitous Scars of GiggXeswick, Attermire, Malham, Yordale and Kilnsey. Bounded on the west and south by these Faults, the Silurian rocks underlie all the highest moun• tains in Yorkshire, forming a tolerably even base, with a general dip to the north-east. Sections exposing the junction of these rocks with the superincumbent Mountain Limestone may be seen beneath Whernside and Ingleborough, in the Ingleton and Dale Becks, and in Clapdale; underlying Cross Fell and Mickle Fell, they may be seen at High Cup Gill, and as shown by Mr. Dakyns, at the Pencil Mill, near Cronkley Scar. Penyghent, and the extensive Limestone Fells of Malham and Kilnsey also have a basement of Silurian Grits. Perhaps the finest section, showing the junction of the two formations, anywhere exposed, is the one chosen for the subject of this photograph. The Silurian Rocks have long been quarried, and are locally known as the Horton Flagstones; they are a bluish grey colour, rather coarse structure, and can be obtained of very large size.
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