OF THE EARTH'S SURFACE. 195 



To account for these dressings, therefore, we must call in the 

 assistance of some extraordinary agent j and this assistance is 

 at hand in the stream flowing from the west, the existence of 

 which we have been led to imagine by the parallel ridges and 

 tails which occur in this district. For the form, situation, and 

 direction of these dressings are such, as a belief in the reality of 

 that stream would lead us to look for. The mere arrangement 

 of ridges stretching east and west, leaves it in doubt from 

 which of these two opposite points the stream flowed ; but the 

 circumstance of the long depositions or tails parallel to these 

 ridges and dressings, which occur upon the eastern side of ob- 

 stacles, such as the rock of Edinburgh Castle, entirely removes 

 that ambiguity, and proves that the stream must have flowed 

 from the westward. 



The grinders must then have been forced to move upwards 

 along the westerly face of Corstorphine Hill, and in that mode 



Bb2 their 



It might also be alleged, that the elevation was performed only in part, when 

 the dressings took place ; and that a further rise had carried the mass, on a sub- 

 sequent occasion, to where it now stands ; but nothing here seems to justify such 

 an intermediate supposition. All the diluvian facts in this neighbourhood, that 

 have come under my observation, concur in denoting one inundation overwhelm- 

 ing the solid mass of this district, which had been elevated into its present posi- 

 tion by some still more ancient revolution of the same sort ; this inundation be- 

 ing the last catastrophe to which it has been exposed. 



Having endeavoured to illustrate the appearance of the dressed surfaces, by re- 

 ferring to abraded rocks in the beds of rivers, I find that some gentlemen, who 

 had heard but a partial statement of my views, conceived it to be part of my sup- 

 position, that these dressings, like those in a river, were produced by water act- 

 ing for a long time. But this is by no means my view ; my theoretical notions 

 limit the action upon the hill under examination, to the passage of a single 

 wave, embracing a period of time that could only be expressed in minutes ; but 

 during that short time, I conceive the water to have been urged forward with 

 such force, and to have carried with it so many powerful agents, that it has pro- 

 duced effects equal to the work of ages under other circumstances. 



