454 THE CANADIAN NATURALIST. [Vol. 



VU, 



depth of thirty or fifty feet ; and a similar condition of the 

 gneissic ledges in Brazil has been noticed by Profs. Agassiz and 

 Hartt, so it may well be admitted that great moving masses of 

 ice, like the glaciers, would have no difl&cult task in breaking 

 up and pushing into the sea these softened rocks, made loose 

 and tender by the percolating rains of untold centuries. Another 

 cause of the rapid growth of the Boulder clay was that the 

 period during which it was deposited was one of subsidence. 

 Whatever mud was poured into the ocean, at the glacier's foot, 

 quickly sank to the bottom in the deep and quiet waters. 



In the next period the conditions were changed, and strong 

 currents invaded the submerged area. In the preceding epoch, 

 glaciers had ground down the rocks to the hard and compact 

 heart of the ledges, so that, except in the already ex' sting 

 Boulder clay, there was no source from which the roving cur- 

 rents of the epoch could draw for the formation of a new group 

 of beds. Of this old glacial deposit they availed themselves ; 

 but, while building up beds out of its coarser materials, they 

 swept off and buried in the depths of the ocean the fine sand 

 and clay. The Syrtensian period was one of elevation, and was 

 therefore one of destruction of deposits, rather than of recon- 

 struction and growth, so that the length of time which elapsed 

 may have been much more than the thickness of its beds indicate. 



This elevation of the land after the withdrawal of the glaciers, 

 is a phenomenon which occurred in other lands, as well as this. 

 Sir C. Lyell, in his Antiquity of Man (page 243, Philadelphia 

 edition, 1863), adduces proof of the gradual and steady upheaval 

 of the land in Scotland since the ice period. And Professor 

 T. Kjerulf, in his treatise on the Striae, Glacial formation and 

 Terraces of Norway (Christiana, 1871), also shews that the 

 hyperborean marine fauna was replaced by more southern forms, 

 as the Norwegian land arose above the sea, after the retreat of 

 the glaciers. 



It will thus be seen that the theory which I have advanced 

 to explained the conditions of the Post-pliocene deposits of Aca- 

 dia, is not without support from the glacial phenomena of other 

 lands. 



