On the Succession of the Older Rocks in the Northernmost Counties of Scotland; with some Observations on the Orkney and Shetland Islands

Abstract

Introduction In this memoir I propose to give a general sketch of the succession of the stratified rock-masses which occupy the northernmost counties of Scotland, or those of Sutherland, Caithness, and Ross, followed by brief notices on the Orkney and Shetland Isles, as determined by former and recent observations. Having commenced to labour in this region in 1826, I then simply gave, as a first result, the account of the Oolitic coal-field of Brora, and of the Lias and Oolites of both the east and west coasts, including the Hebrides, with brief allusions to the bituminous schists of Caithness containing fossil fishes*. For, although I even then had traversed portions of the crystalline rocks, I considered all such masses as out of the sphere of my observation, presuming that their mineral and other characters had been adequately made known by Macculloch and others who were looked upon as authorities. In short, it was deemed a sufficient effort for a young geologist, as I then was, to point out the relative position of certain members of the Secondary series, to collect their organic remains, and to show the relations of such strata to their equivalents in England. In the following year Professor Sedgwick and myself, devoting our efforts to the examination of the structure of the Northern Highlands, produced a memoir in which, after a brief allusion to the older and crystalline rocks, we gave the first account of the true order of the Old Red Sandstone and superposed masses, which we