POSTPONED PAPER. 



On the Succession of the Eocks on the Noeth Coast of Scotland. 

 By John Millee, Esq. 



(Communicated by Sir E. I. Murchison, F.G-.S., &c.) 

 [Eead December 15, 1858.] 



In the summer of 1841, I made a geological tour through the 

 northern half of the county of Sutherland as far as Cape Wrath, 

 and T returned from my trip acquiescing in the opinions which then 

 prevailed regarding the succession of the rocks on the north coast of 

 Scotland. 



Dr. M'Culloch had described the mineralogy, succession, and rela- 

 tions of the rocks between Cape Wrath and the Eiver of Hope in his 

 usual vigorous style as early as 1819, and, considering the state of 

 geological science at that period, with wonderful precision and cor- 

 rectness ; but he stopped short in his researches at the point just 

 mentioned, and left to others the task of describing the geology of 

 the north coast continuously from the Atlantic to the German Ocean. 

 This task was, however, accomplished by Messrs. Sedgwick and 

 Murchison, who laid the result of their labours before this Society in 

 1828. In their memoir the gneiss of Cape Wrath is regarded as the 

 base of the system ; and, proceeding eastward, it was assumed that 

 the conglomerate and red sandstone of Cape Wrath came next in the 

 ascending order, and were the true Old Eed Sandstone, — that the 

 conglomerate and sandstone of Tongue and its neighbourhood were 

 of the same age, — and that from Strathy Bay to the German Ocean at 

 Duncansby Head, the Old Eed Sandstone rocks of Caithness extended 

 in three great divisions, of lower or conglomerate, middle or flag 

 scliists, and upper or newer red sandstone. Eegarding the lime- 

 stones of Duirness, no decided opinion was pronounced. 



In 1839 Mr. Cunningham published his little work on the Geo- 

 gnosy of Sutherland, in which, in addition to a mass of most valuable 

 mineralogical facts and observations of his own, he corroborated the 

 opinions of M'Culloch regarding the succession of the rocks from 

 Cape Wrath to the east side of Loch ErriboU ; and he did more : he 

 clearly laid down the doctrine that the great central gneiss which 

 overlaid the limestone of Loch ErriboU and extended from that point 

 eastward to Caithness must be regarded as a more recent gneiss 

 than that of Cape Wrath, and that the conglomerates and sand- 

 stones of Tongue, Portskerray, and the east coast of Sutherland were 

 also newer than the sandstones of Cape Wrath, and must rank as a 

 distinct and more recent formation. But Mr. Cunningham's work was 

 not written in an attractive style and did not excite much interest. 



In the mean time various geologists had searched for fossils in the 

 red sandstone of Cape Wrath and in the limestones of Duirness, as 

 without their evidence any classification of the rocks could only be 



