XV. Notes on the Geology of South-east Arran

Abstract

The rocks exposed along the shores of S.E. Arran belong to the upper member of the lower division of the Trias. The red sandstones of Clauchland shore and Holy Isle are seen to pass upwards into a series of yellow and white sandstones, the latter being in places highly calciferous, and, consequently, weathering into very irregular forms through the solution of the contained carbonate of lime. On the inland hill slopes these rocks are seen to pass conformably upwards into a great series of red, mottled, and olive green, marly sandstones and shales, which are classed as Upper Trias, and are probably the equivalents of the Keuper series. The whole of these rocks dip westward at low angles, and the Upper Trias alone, unless repeated by faults, must attain a thickness of about 1000 feet. With the possible exception of a few occasional markings like worm tracks, the whole series appears to be destitute of any evidence of organic existence. An outstanding feature of the geology of this district is the numerous basic sills intruded among the sandstones, which do not seem to have reached the surface at the time of intrusion, but have been laid bare by subsequent denudation. One of the best exposures of these sills occurs at the south end of the Holy Island and along the shore westward of King's Cross Point. Tracing the sill from the east, it rises from under the waters of the Firth, and passes upwards across the horizontally bedded sandstones, till This 250-word extract was created in the absence of an abstract