Tronsactioiis. 73 



hundred feet of water. Somewhere or other high laud ilid 

 exist, the positioa of which may yet be traced from the 

 erratics iu the breccia. 



Upon the higher parts of this land the climate was cold 

 enough to allow of the formation of glaciers, which moved 

 down through the valleys, their natural courses. Naturally, 

 in their progress downwards, as in glacievs of the present 

 day, rubbish of various kinds tumbled down upon them, and 

 •was carried oft", the stones suftering little or no erosion from 

 their position upon the top of the moving ice. These 

 glaciers, when they arrived at the sea, which was not vet 

 frozen up, would break oft", carrying with them the rubbish 

 from the sides of the valleys. In lower latitudes these would 

 melt and, of course, deposit their burden, which would thus 

 give rise to the glacial breccia which we have described. 



After this had continued for some time a great change 

 took place in the physical geography of the district — the 

 submerged land once more changed to teii^a Jirma. Neces- 

 sarily this land became subject to the denuding agents — 

 rains, frosts, rivers, &c., whicli, as I have already said, nearly 

 obliterate every trace of the breccia. 



Glacial conditions were evidently not very severe at this 

 time ; perhaps there might even have been an inter-glacial 

 warm period. After this state of matters had lasted for a 

 long time conditions began to change. A glacial climate 

 gradually came on, culminating in the formation of a vast 

 sheet of ice, which in its motion produced the Boulder Clay. 



Such are a few of the more important features of this 

 interesting deposit. A more exhaustive study of its chai-ac- 

 ter may modify them to some extent, and, doubtless, will 

 reveal many important facts which may throw further light 

 upon the physical history of Dumfriesshire 



