42 Lord Greenock on the Igneous Rocks 



ably and correctly executed by Dr Greville, F. R. S. Ed., than 

 by any written description (See Plate). The first appearance of 

 disturbance commences to the eastward of the limits of the 

 drawing in that direction, and about 200 yards from the point 

 of junction between the secondary rocks and the trap, where the 

 former may be observed to rise at an angle of about 11° or 

 12° above the level of the road, crossing a footpath that leads 

 up the declivity. Owing, however, to the partial covering 

 of soil and vegetation, several of the strata can be traced only 

 here and there, by their edges cropping out. There appear to 

 be about five or six strata of sandstone in all, varying in thick- 

 ness from two or three feet to a few inches, the intervals between 

 them being occupied by beds of slate-clay, or perhaps of marl, 

 of a reddish-brown or purple colour ; but in their present state, 

 neither the continuity of the one, nor the nature of the other, 

 can be distinguished with any accuracy. 



The irregularity and want of conformity in the stratification 

 of these rocks, and the curvatures observed in them, are very re- 

 markable, giving such strong evidence, that, whatever the cir- 

 cumstances might have been which influenced their original de- 

 position, they must subsequently have experienced a considerable 

 derangement, as to leave no doubt in the author's opinion, that 

 the signs of disorder so manifestly visible in this section, are to 

 be attributed to some subterraneous agency. In this view, the 

 only rational explanation that occurs to him is, that they were 

 occasioned by that general disturbing cause, which probably act- 

 ed upon a large extent of country at the period when it was ele- 

 vated above the waters, beneath which it had been originally 

 formed. Considering the subject, therefore, in this light, it ap- 

 pears probable that the whole of the sandstone strata, with the 

 intervening beds of slate-clay or marl, had, on the first impulse 

 they received during the process of elevation, a tendency to rise 

 in a uniform direction ; but, in consequence of some violent dis- 

 turbance that must suddenly have interrupted the regularity of 



