72 Transactions. 



we may proceed with some confidence to decipher it. And 

 first, as to the origin of these two formations — It is very 

 evidently vindicated that the boulder clay has not been 

 deposited in water, while the underlying breccia has. To 

 prove this [ need only point to the absence of stratification 

 in the former, and its presence in the latter ; as well as the 

 confused mixture of clay, sand, and boulder in the one, and 

 their regular arrangement into beds of shale, sandstone, and 

 breccia in the latter. 



In the second place, it is equally evident that the strati- 

 fied deposit has been transported by the agency of floating 

 ice, while the boulder clay derives its origin from land ice. 

 The great angularity of the boulders and their mode of 

 occurrence in the case of the former, make such a theory 

 imperative. It likewise accounts for the absence of boulders 

 from local Carboniferous and Ponnian rocks, and for the 

 presence of fragments of rocks which do not belong to the 

 district. 



As to the boulder clay, if it has been formed on land, 

 necessarily it must be due to glaciers. In the third place we 

 may proceed a step further in our reasoning, and say that 

 subsequent to the deposition of breccia, and previous to that 

 of the boulder clay, a considerable period must have elapsed 

 durino- which Middle Nithsdale was raised out of the water, 

 and suffered a great amount of denudation, nearly obliterating 

 every trace of the glacial breccia, which must have covered 

 the whole valley to a depth of more than 100 feet, as it is 

 utterly impossible to believe that the icebergs got relieved 

 of their burden always at one restricted spot. 



With these detached fragments of past events, is there 

 not a possibility of adding an interesting chapter to the 

 physical history of Dumfriesshire 1 According to my deduc- 

 tions from these glacial deposits, the skeleton of such a 

 chapter would read as follows, and I leave you to judge of 

 the reasonableness of it :— At some very early stage of the 

 glacial epoch Middle Nithsdale, with an unknown part of 

 the surrounding country, was submerged under several 



