312 Mr. MuRCHisoN on the Coal-field of Brora in Sutherlandshire, 



House, where the sandstone with calcareous spheroidal nodules rests upon 

 the shale ; and the former rising- high in the precipitous cliir, is overlaid and 

 broken by trap and basalt. The structure of this sandstone is identical with 

 that of many beds upon the Yorkshire coast, and natural caves are of fre- 

 quent occurrence in it *. 



Limestone containing- imperfect fossils occurs in the uppermost beds, and 

 also a lignite which has been partially worked for fuel : but I could not 

 distinctly ascertain the order of superposition in the higher parts of the cliff; 

 for here, as well as upon the N. E. coasts of Skye, it is in the lower part only 

 that there is any regularity of stratification, the summits being invariably ob- 

 scured by superincumbent trap. 



The strata on the S. coast of Mull reach to nearly as high elevations as in 

 Skye ; but to the west of the rugged shore of the Ininiore of Carsaig they are 

 gradually brought down, and are obliterated by the basaltic rocks which form 

 the wild and gigantic promontories of Ben Macquarrie and MacCullum's 

 Pointf. 



The preceding details have shown that upon the N.E. coast of Scotland, 

 the strata above the lias are visible only in low cliffs, or in beds exposed at 

 ebb tides ; the distance which they occupy at intervals from N. to S. being 

 about 40 miles, and their greatest breadth from E, to W. about 3 miles. 



On the N. Western coast, different members of the same series are to be 

 traced, through a space of 120 miles, from the Shiant Isles on the N. to the 

 S. coast of Mull, frequently swelling into cliffs of great height. They are, 

 however, so traversed and overlaid by trap and basaltic rocks, that the precise 

 relations of one bed to another are in many situations rendered equivocal, 

 although the fossil remains of the whole suite are clearly referrible to various 

 oolitic formations, which are seen to be based upon the lias. 



In the Brora district, however, each bed has been distinctly assigned to its 

 equivalent in England. The strata containing the coal iiave been shown to 

 be identical with those of the Eastern Moorlands of Yorkshire, which are the 



* One of the largest and most remarkable of them is called the Cave of the Nuns ; and the 

 spheroidal nodules above described project from its sides and roof. The sandstone is quarried 

 near the cave, which is used as the abode of the workmen. Communication with tlus seques. 

 tered habitation can only be made by sea. 



•J- For a picturesque sketch of this unfrequented spot, I refer the reader to the Earl of Comp- 

 ton's Views, illustrative of his memoir on the trap-rocks of this coast. (Geol. Trans, vol. v. 

 part 2.) and for the singular changes which some of the stratified beds undergo in contact with 

 these basaltic masses, the geologist must consult the " Western Islands " of Dr. MacCuUoch. 



