12 PROCEEDINGS OF THE GEOLOGICAL SOCIETY, [April 18, 



has been elevated by it, as we learn at the Eatbie burn ; and the 

 oolitic beds have been shattered, as seen near the Ord of Caithness * . 

 Hence we must date the formation of at least the ridges in which 

 these appearances are presented, at the close of the oolitic period. 

 But one of such ridges is that which runs (with occasional cross 

 fractures) along the entire north-western side of the Great Glen, 

 rising to its greatest height in Mealfourvonie. A very cursory in- 

 spection of the district leads us therefore to infer the time of the 

 formation of the Caledonian Valley to have been subsequent to the 

 deposit of the oolitic series ; and if we might venture on the idea 

 that outbursts of igneous rocks of a particular character (as for in- 

 stance granite), within not very extensive areas, were synchronous or 

 nearly so, the extent and position of this fracture lead to the con- 

 jecture, that to this later date we must assign the ultimate elevation 

 of the Grampians, and the more striking physical outlines of the 

 Highlands of Scotland. 



It is still further clear that great denudation of the country has 

 taken place at a subsequent period. The faults produced by the in- 

 trusion of this granite, amounting, as we have said, in some instances 

 to several hundred feet, have been planed down to a perfect level on 

 each side. This is most distinctly seen in the neighbourhood of the 

 lias beds at the burn of Eathie. The vast rem.aining masses of the 

 old red conglomerate, capping in horizontal strata several hundred 

 feet in thickness lofty mountains on the western coast, are in reality 

 but the base of the Old Red system, the middle and upper portions 

 having totally disappeared; whilst a great tract of central country 

 has been swept entirely clean of the whole series, upper, middle and 

 lower f. A large portion of the removed mass is no doubt to be 

 found in the boulder-clay and the drift-gravel series ; yet I cannot 

 but think that the greater destruction of the strata, the great wear 

 and tear of the country, had taken place during its earlier emergence 

 from the ocean, by the ordinary action of the waves and the atmo- 

 sphere. 



I think the evidence which I shall presently adduce is sufficiently 

 strong to prove that the commencement of the post-pleiocene or 

 glacial epoch was, so far at least as regards the North of England and 

 Scotland, a period of subsidence of the land. The relative level of 

 the sea was probably at its commencement not greatly different from 

 that which now exists. I infer it from the following considerations |. 



The groovings and scratchings of the rocks under the boulder-clay, 



* ** The granite of this coast must have been elevated at a period subsequent to 

 the deposition of the oolitic strata." (Sir R. I. Murchison in Geological Transac- 

 tions, vol. ii. 2nd series, p. 353.) 



t In the less elevated and less exposed districts of Moray, Ross, and Caithness, 

 the upper and middle portions of the Old Red system have been better preserved. 



X I have been happy in finding my views in this respect agreeing with those of 

 Mr. Hugh Miller, worked out at the same time quite unconnected with each other ; 

 and since drawing up this paper, I observe that Mr. Darwin has from other data 

 inferred the same in reference to the glacial deposits of Wales, as Mr. Trimmer 

 has in reference to those of Norfolk. See Quarterly Journal of the Geological So- 

 ciety, Nov. 1848, p. 321. 



