LAKE MARGINS. BOGS AND TEATY SWAMPS. 35 



Fig. 8. — Coverings of Diatomacene from Recent Fresh-water Deposits, Nova Scotia, — magnified. 



Lake Margins in Nova Scotia are of some geological interest, 

 from the effects of ice-pressure which they exhibit. The expansion 

 of the thick icy sheet which forms on the surface of our lakes in 

 wintei", and its drifting to and fro when loosened from the shores 

 by the thaws of spring, heap up very remarkable ridges and embank- 

 ments of stones, gravel, and earth. In low and muddy shores, 

 these actions of the ice, I believe principally the latter, push up long 

 mounds, which look as if an attempt had been made to raise an 

 artificial dike ; and where the shores consist of small stones and 

 gravel, still more regular structures are sometimes produced. Oc- 

 casionally there are two mounds, one within the other, marking 

 different levels of the water ; and I have seen these mounds still 

 remaining, in places where lakes and ponds had been long since 

 filled up and converted into bogs. On rocky shores, large stones 

 are pushed against the bank and packed together until they form 

 huge sloping Cyclopean walls, which testify not only by their mass, 

 but by the manner in which they have been wedged together, to 

 the force that has been applied to them. This last appearance is as 

 well seen in some of the upper lakes of the Shubenacadie as in any 

 others that I have examined. These modern effects of Ice-pressure 

 will serve to explain some of the phenomena of the drift or boulder 

 fonnation which overspreads the surface of the province. They are 

 also curious from the resemblance which they bear to glacier moraines, 

 for which they might, in some cases, be easily mistaken. 



Bogs and peaty sicamps fonn another class of modern deposits 

 which I may notice here. They are very numerous in Nova Scotia, 

 especially in the rocky districts of the Atlantic coast. The largest^ 

 that I have observed are the SavijiiialiS-jnjar Clyde River in Shel- 

 burne, and the Carriboo bog of Aylesford. AVith respect to the 

 geological features of these deposits, I may notice : First, That they 

 consist of vegetable matter which has grown on the spot, and has 

 accumulated, because in water-soaked soils the decay of dead vege- 

 table substances proceeds more slowly than the acquisition of new 



