284 AN ENQUIRY INTO THE NATURE OF [Ch. XIII. 



means or other, produced a separation (almost without^any 

 fracture) of the crystalline constituents of the rock." * 



But it is a curious circumstance, that, whilst the oolite is 

 supposed, at Sandside Bay, to have furnished part of the 

 materials of the breccia, the old red conglomerate of Bad-na- 

 Bae had no share in furnishing its quota; but that the 

 fragments are here entirely derived from the granite, not 

 merely its surface having been broken up, but the solid rock, 

 to the extent of about half a mile in thickness. This ex- 

 planation may be calculated to meet the difficulties of the 

 case, but can it be supported by any known analogy ? 



It may also be remarked, that the old conglomerate is 

 generally arranged in highly inclined strata, either in contact 

 with granite, or with the intervention of the granitic con- 

 glomerate : the angle of the dip, however, is very various, 

 and sometimes approaches the horizontal : " in Kerwick Bay, 

 for example, the old red conglomerate is distinctly stratified, 

 and dips north at an angle, which is inconsiderable when 

 compared with the high inclination of the primary rocks on 

 which they rest." t 



So also the old conglomerate of the mountains of Apple- 

 cross occurs in regular strata, which are inclined at a mo- 

 derate angle. J And the same fact has been observed in many 

 places in the north of Scotland. These strata are not only 

 slightly elevated in some cases, compared with the primary 

 schistose rocks, but also rest on the latter in an uncon- 

 formable position. " Thus, in a deep gully two or three 

 miles from Cape Wrath, the laminae of the gneiss are nearly 

 vertical, while the beds of conglomerate are not inclined at 

 a greater angle than 25." Also, " the hill of Craig-na- 

 Vrechan is composed of old conglomerate dipping off the 

 coast, at a low angle, and resting unconformably upon the 

 micaceous slate-rocks of this district." 



* Geol. Trans. (New Series), vol. iii. p. 140. f Ibid. p. 127. 



f Ibid. p. 155. Ibid. p. 154. || Ibid. p. 127. 



