Ch. XII.] relation of lakes to glacial ACTION. 169 



nent, others from islands covered with glaciers, like South Georgia, 

 which must now be centres of the dispersion of drift, although situ- 

 ated in a latitude aoreeino; with that of the Cumberland mountains in 

 England. 



Xot only are these operations going on between the 45th and 60th 

 parallels of latitude south of the line, while the corresponding zone 

 of Europe is free from ice ; but, what is still more worthy of remark, 

 we find in the southern hemisphere itself, only 900 miles distant from 

 South Georgia, where the perpetual snow reaches to the sea-beach, 

 lands covered with forest, as in Terra del Fuego. There is here no 

 difference of latitude to account for the luxuriance of vegetation in 

 one spot, and the absolute want of it in the other ; but among 

 other refrigerating causes in South Georgia may be enumerated the 

 countless icebergs which float from the antarctic zone, and which 

 chill, as they melt, the waters of the ocean, and the surrounding air, 

 which they fill with dense fogs. The contrast of climate and glacial 

 conditions in corresponding zones of the northern and southern hemi- 

 spheres, and even in corresponding latitudes on the same side of the 

 equator, makes it highly probable that the extreme of cold in the 

 glacial period was not experienced simultaneously in North America 

 and Europe. 



Connection of the predominance of lakes with glacial action. — It 

 has been truly remarked that lakes are very common in those coun- 

 tries where erratics, striated boulders, and rock surfaces, with other 

 signs of glaciation abound ; and that they are comparatively rare in 

 tropical and subtropical regions. When travelling over some of the 

 lower lands in Sweden, far from mountains, as well as over the coast 

 region of Maine in the United States, and other districts in North 

 America, I was much struck with the innumerable ponds and small 

 lakes, of which counterparts are described as equally characteristic of 

 Finland, Canada, and the Hudson's Bay Territories. I have never 

 seen any similar form of the surface south of latitude 40° N". in the 

 western, and 50° IS", in the eastern hemisphere. The relation of a 

 certain number of these sheets of water to the glacial period is obvi- 

 ous enough, for not a few of them are dammed up by barriers of 

 unstratified drift, such as may have constituted the terminal and late- 

 ral moraines of glaciers, or may have been thrown down from melting 

 icebergs when the country was still under water. To this class of 

 lakes and ponds the term " morainic " has been applied. But I agree 

 with Professor Ramsay, that the origin of. many, even of the moder- 

 ate-sized depressions now filled with water, cannot be so explained, 

 because many of them have their barriers formed of solid rock. 



With reference to cavities of large dimensions containing water in 

 mountainous regions, they have been truly said to lie almost universally 

 in the course of valleys of erosion, being, like them, narrow in propor- 

 tion to their length. If many of them run in the lines of great rents 

 and faults, traversing the older rocks, this is no more than may be 



