356 The Scottish Naturalist. 



decidedly spoke of an "ancient" and the present or "modern" 

 level of the channel of the river. 



There are only two sides to this question. On the one, there 

 is a necessity for a much larger quantity of water to have been 

 constantly coming down the valley; or, the river, being much 

 what it now is in volume, was once on a time at a higher level 

 than it at present occupies. Let us consider the aspect of the 

 first proposition, viz., that of a vastly greater body of water 

 coming down the valley. Such a body of water is not a mere 

 hypothesis, for the melting of the last of the glaciers probably 

 let loose a superabundance of water quite sufficient to submerge 

 both the lower and the higher haughs. But did this water come 

 down in the guise of a river as gentle in its operations as is the 

 present river Earn? We should rather, if the high haugh is the 

 work of such an erratic, ice-supplied stream, look for pebbles 

 and boulders to be scattered in its clays and sands in an eccen- 

 tric manner. This is, however, not at all the case ; no ice- 

 borne fragment occurs in its bed, or, allowing certain stones to 

 be ice-borne, they have been re-arranged since they were dropped 

 by travelling fragments of icebergs ; indeed if coarseness of 

 material be an indication of anything whatever, there is greater 

 coarseness in the deposits of the lower, than of the upper haugh. 

 The glaciers may have melted so gradually, that no indication 

 of ice was conveyed down the valley, but such a slow melting 

 would not have supplied the enormously larger body of water. 

 And if the receding glaciers did not yield the floods, where was 

 the extra watershed ? One can hardly assume that the rain-fall 

 was so much greater when the Earn was first a river, than it is 

 now. The difference in the height of modern floods of the 

 Earn, and those necessary for the formation of the higher haugh, 

 is not less than 26 feet, and is possibly greater. Were this pre- 

 sumed higher state of flood in the Earn valley again to come 

 about, it would no doubt soon raise the surface of the lower 

 haugh to the height of that of the higher ; and then we should 

 have a river-deposit, from the bottom of the stream to the top 

 of the haugh, 40 feet at least in thickness, and this deposit 

 undoubtedly would exhibit a fluviatile construction through- 

 out its entire thickness (see nature of this in former paper, com- 

 mencing on pp. 264 and 314, vol. II. Scottish Naturalist); 

 and, therefore, supposing our higher haugh to have been 

 originally thus deposited, it also should exhibit a similar 

 arrangement of coarse pebbles and sands at its very bottom, 



