1873.] JUDD— THE SECONDARY EOCKS OF SCOTLAND. 123 



along a line striking N.E. and S.W., and passing through the town 

 of Cromarty, the metamorphic strata of Silurian age are upheaved ; 

 and this movement has been attended with great disturbance of the 

 Old Eed Sandstone strata, which, in the neighbourhood of the 

 gneissose, quartzose, and schistose rocks of the Silurian, are seen 

 lying at high inclinations and with numerous folds. The remark- 

 able ridge of metamorphic rocks is cut through by the present en- 

 trance to the Cromarty Firth *, and forms those striking headlands 

 the North and South Sutors of Cromarty. The length of the ridge 

 of Silurian rocks is about nine miles ; but certain masses of granite 

 which appear to the S.W. may probably be considered a continu- 

 ation of it. A glance at the position of this ridge of hard rocks will 

 suffice to show to what an extent the existence and form of the two 

 great eastern peninsulas of Ross-shire, Easter Ross and the Black 

 Isle, have been determined by it. 



Lying against this ridge of upheaved and disturbed strata we find 

 on the shore three of the patches of Jurassic strata already referred 

 to, namely those of Port-an-Righ, Cadh'-an-Righ, and Eathie Bay. 

 Situated in small recesses of the coast, between headlands of the 

 harder rocks, these patches, which have already been denuded away 

 to a level below that of high water, are evidently the last vestiges 

 of a tract of land which once fringed the high lands of Ross, in the 

 same manner as the low Oolitic district in the south-west of Suther- 

 land now forms a border to the mountains of that county. No one 

 can study these two remarkable and interesting districts without 

 being struck by the fact that here we have a repetition of the same 

 phenomenon, produced by the action of the same succession of 

 causes, but exhibited to our study at two different stages of its 

 history. The two districts mutually explain one another ; and it is 

 evident that while on the one hand the south-east coast of Ross must 

 once have exhibited a tract of low-lying land composed of Jurassic 

 strata like that of Brora, this last must at some future period be re- 

 duced, by the continued action of existing causes, to a condition 

 analogous to that of the former. 



About a mile southwards from the village of Shandwick there ap- 

 pears the first of the patches referred to f . The strata are seen only 

 at low water, and then present a singular appearance : they are 

 bent into long folds and dip seawards at a considerable angle ; and 

 being composed of indurated shales with a few harder bands of 

 argillaceous limestone, they have been worn into a series of step-like 

 ridges, which have been not unaptly compared by Sir Roderick Mur- 

 chison to the seats of an ancient amphitheatre. These strata are 

 also broken up by a number of small transverse faults, which have 

 produced lateral displacement of the beds. The relations of these 

 strata to those of the Old Red Sandstone against which they lie are 

 illustrated by the plan and section, figs. 6 and 7. 



* See Murchison, Trans. Geol. Soc. 2nd ser. vol. ii. pt. 3. p. 355. Geikie, 

 'Scenery of Scotland,' p. 132. 



t First described by Sir Eoderick Murchison, to whom it was pointed out by 

 Sir George Mackenzie. Trans. Geol. Soc. 2nd ser. vol. ii. pt. 2. p. 307. 



