BY A TARN SIDE. 7 



power of such a depression is evident, and in this 

 way a tarn springs into creation at once. In the 

 steepish bluffs which form the sides you may see 

 imbedded stones and boulders. Some of them are 

 angular, and indicate they must have been removed 

 from their parent rock direct, and by some agent 

 that could carry them without exposure to much 

 abrasion. Others are water-worn, and show that 

 they had been rolled about before their final removal 

 to this spot. You are not long before you notice 

 that many of these boulders, big and little, are 

 strangers to the rocks of the locality, and have come 

 from a distance, chiefly from rock strata lying towards 

 the north. You are not wrong in your deduction, 

 and a closer examination shows you that many of 

 them are scratched, some to a considerable depth, 

 and that others, of a harder texture, are polished. 

 Here you obtain a glimpse of the nature of the con- 

 veying agencies. It was ice ; and when the bonlders 

 were transported, the tarn occupied an inconsiderable 

 space along the bottom of an extensive ice-sheet, 

 where a moraine profonde, or stratum of mud, 

 stones, &c., had accumulated, to form the boulder- 

 clay of the neighbourhood. What wonderful 

 changes have been wrought since then ! This old 

 moraine has been elevated into dry land, has 

 been scooped out into valleys, and sculptured into 

 hills ! The animals and plants of the old wintry 

 period have departed to their original frosty zones, 

 and more temperate forms have occupied these 



