490 MR MILNE ON THE GEOLOGY OF ROXBURGHSHIRE. 



above views are correct, there would, on its emergence, be deep gutters nearly 

 parallel, cut through the whole of it. In the central, because the lower parts, the 

 largest portion would be scooped away, and along a line corresponding with the 

 general slope. At the sides, gutters and ridges would be formed nearly parallel to 

 these sides, if the range of hills composing them did not rise high ; but, if other- 

 wise, the ridges and banks between the hollowed channels, would be slightly in- 

 clined away from the sides, and converge towards the lower part of the valley. 

 On the complete emergence of the land, the central parts of the valley would, of 

 course, be occupied by a river, which would gradually undermine and carry off 

 what gravel and sand had been left there. The lateral ridges and mounds at a 

 distance from the river, would continue undisturbed except by the minor influence 

 of rain and rivulets. 



Suppose now the case of two valleys with a ridge between them, both nearly 

 filled up as before with sand and gravel. On the waters rushing off by a rapid 

 rising of the land, deep cuts, and high banks between the cuts, would be formed, 

 as above explained, the middle of the valleys being the places where the least 

 quantity of gravel would be left, and the sides being the places where the gravel 

 banks would be most undisturbed. Then at the end of the ridge dividing the 

 two valleys, the sand and gravel would be little affected on the lee-side of the hill, 

 so that, in such a situation, it is easy to conceive how a ridge or bank should be 

 left, having a direction corresponding with the average direction of the two val- 

 leys which had guided the rush of water on each side of it. 



It appears to me perfectly possible to explain in the way now suggested, many 

 of the banks and ridges of gravel which exist in Roxburghshire, and, in particu- 

 lar, those at Liddell Bank, and near the Elland or Allan Water, described in the 

 first part of this Memoir. The one at the place last mentioned, though now in 

 some places broken down into a series of knolls, has originally been parallel, or 

 nearly so, to the general axis of the Gala valley, and had extended for about three 

 quarters of a mile in length. It is evident that if, when the land emerged from 

 the sea, its surface had anything like the form which it now has, the great rush 

 of waters must have been on the north and south sides of this bank, so that in 

 their progress eastward, the waters must have had comparatively little effect on 

 the gravel accumulated there. Then as to the Liddell Bank ridge of gravel, if 

 the waters rushed off by a sudden rise of the land, which is the case supposed, 

 that ridge being situated at the west end of the hill or range of hills which divides 

 the Merse and Liddell valleys, the detritus there must have been protected by the 

 hill, and thus would form an elongated bank, its upper end inosculating with the 

 east side of the hill. 



These effects, however, would follow only on the assumption, that the land rose 

 with sufficient rapidity to produce a rush of waters, 



