484 MR MILNE ON THE GEOLOGY OF ROXBURGHSHIRE. 



so that the height of the impinging column would certainly be ample for its pro- 

 pulsion. Reckoning your granite boulder at say 5 feet diameter, a column of 

 water 15 feet high would give a dynamical action on it, greater than its entire 

 weight in air, and of course equal to its propulsion on any surface, 2.5 is, I think, 

 about its specific gravity." 



Mr SCOTT RUSSELL thus distinctly concurs with Mr HOPKINS as to the trans- 

 porting power of a wave produced in the way above supposed ; and if these opi- 

 nions are well founded, then there seems no difficulty in explaining how the granite 

 boulders of Liddesdale were brought from Criffel. 



But, in addition to waves in the ocean, produced by submarine earthquakes, 

 there must have been currents, which, if of sufficient rapidity, must, as it appears 

 to me, have been still more effectual in accomplishing the results in question. 

 That currents, and of great force and extent, existed in the ocean which, at the 

 epoch of these boulders, covered the district, is proved by the bared western faces 

 of the hills, and the residuum of diluvial debris on their east sides ; and it will 

 by-and-by be shewn, that these debris could have been spread over the entire 

 country, by no other cause than currents of water. The origin of these currents 

 all from the westward it is certainly difficult to account for ; but the fact of 

 their existence seems indubitable, and also of their having had such a force and 

 velocity, as is quite sufficient to have transported boulders. 



(2.) The next phenomena to be noticed are the accumulations of clay, gravel, 

 and sand. 



In the former part of this paper, I mentioned that the only place where I 

 had observed the well-known boulder clay, which is so largely developed in Mid- 

 Lothian, is in the neighbourhood of Kelso. The deposit there is filled with huge 

 blocks of basalt, greenstone, greywacke, and porphyry rocks, of which none exist 

 in the neighbourhood in situ. The blocks, by their rounded forms, indicate very 

 plainly that they have been rolled from a distance ; and as no rocks of the same 

 characters exist towards the eastward, there is great probability, if not absolute 

 certainty, that the blocks in question, as well as the clay in which they are im- 

 bedded, were, by the force of water, transported from the west. The clay is not 

 stratified, and there are no layers of sand in it. Moreover, the imbedded boulders 

 are not deposited according to size or weight. Judging from these circumstances, 

 I should say that this boulder clay must have been deposited by waters of great 

 power and violence. 



Above this boulder clay there is a deposit of gravel and sand, which forms a 

 skin, as it were, over the whole country. It is to be seen distinctly covering the 

 boulder-clay at Hadden. The pebbles do not generally exceed the size of the fist. 

 They are, in every place which is known to me, rounded and apparently water- 

 worn. There are occasionally extensive beds of sand, which alternate with the 

 layers of gravel. 



