the Upper Districts of Aberdeenshire* 



19 



That such a hollow might be formed by the crater of a volcano, 

 is an idea altogether preposterous. That it might have been form- 

 ed by the disintegration of a portion of the mountain, following 

 the supposed natural curvature of the granite concretion on the 

 large scale, is hardly less so. The blocks and stones, converted 

 into gravel, might be washed away ; but they would not leave a 

 hollow for a lake, but a plain or curved slope. The accompanying 

 diagram. Fig. 4. represents the supposed original form of the sup- 

 posed strata, which might by supposition be inferred to produce the 

 phenomena : a, a, a, the seams of stratification ; b, b, b, the present 

 surface line. But I have nowhere seen traces of such curved lines 

 in the precipices, which are invariably marked by more or less per- 

 pendicular fissures, with transverse cracks. 



Fig. 4. 



Lastly, At the original formation of the mountains, or subse- 

 quently, a mass might have subsided, leaving an edge of abrupt 

 rocks : or when the mountain was raised up from beneath, the part 

 which now forms the bottom of the corry being already consolidat- 

 ed, or from various causes not being liable to be acted upon by the 

 upheaving force, remained in the position which it had assumed, 

 while a neighbouring part, separated perhaps by a deep rent, had 

 been thrust up. Other means might easily be imagined to produce 

 the effect. 



