348 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



granite by which they are penetrated also belongs to a prior epoch. 

 The elevation of the secondary strata to their present situation, the 

 fracture of the boulders contained in the great conglomerate, and 

 the faults and fissures in the sandstone, may have been caused by 

 elevations in the line of the Grampians or of the great Caledonian 

 Valley at an epoch, most probably, posterior to the deposit of the, 

 lower Purbeck beds, which, at Linksfield, have been bent and frac- 

 tured by the elevation of the subjacent cornstone. 



2nd. The great conglomerate and red sandstones, containing fish 

 of the genera Dipterus, Dijplopterus, Cheirolepis, Cheir acanthus, Ooc- 

 costeus, (fee, represent the Orkney, Caithness, and Gamrie rocks in 

 Scotland, and the inferior division of the Old Red Sandstone of 

 England. 



3rd. On these are superimposed a series of marly conglomerates 

 and sandstones (containing cornstones), which are characterized by 

 a distinct and very characteristic series of fossils, and are equivalent 

 to the central division of the Old Red system to the south of the 

 Grampians, and in England. 



4th, and lastly, the superior siliceous conglomerates and sandstones 

 without fossils occur, but no indications of the coal-strata. 



These conclusions are perfectly consistent with the appearances 

 presented by the strata containing ichthyolites in other parts of the 

 north of Scotland. The Rev. Mr. Clouston, of Shandwick, informs 

 me that the succession of strata in Orkney* is as follows : — A coarse 

 conglomerate, several hundred feet thick, rests on the primary rocks, 

 and passes above into argillo- calcareous bituminous schists containing 

 the fish ; these schists, like the sandstones associated with them, dip 

 from the primary rocks at an angle of 20°, and on these the soft red 

 sandstones of Hoy are believed to rest. The whole of these strata 

 are penetrated by greenstone -dykes. 



At Cromarty, the great conglomerate dips imder the sandstones 

 (containing fish-scales) that rise to the hill called the North Sutor, but 

 is hardly to be traced under the fish-beds of the South Sutor, the 

 relations of which are otherwise nearly the samef. But, as I hope 

 that the many interesting phenomena exhibited near Cromarty wUl be 

 described in detail by Mr. Miller, I shall only state my conviction that 

 the vertical position and altered appearance of the Old Red Sandstones 

 on each side of this singular rock are not to be ascribed to the in- 

 trusion of the granite -veins, by which the gneiss, forming the sum- 

 mits and much of the sides of the Sutors, is penetrated, but to the 

 eruption of a very siliceous trappean rock, posteriorly to the de- 

 posit of the lias, which has raised the gneiss into dome-shaped hills, 

 and, near the remarkable rock called " M'Earquhar's Bed," has 

 brecciated the sandstones, and altered the nearest strata that con- 

 tain fish. The first observation that led to this opinion was made 

 in 1837, at a place a little to the east of where the sandstones of the 

 Bay of Cromarty wrap round the extremity of the hill. There, 



[* See also Appendix.— Edit.] t Geol. Trans. 2nd ser. vol. iii. p. 150. 



