68 MAN AND THE GLACIAL PERIOD. 



whole line of moraines, from the end of Cape Cod to 

 Brooklyn, 1ST. Y., consists of a reticulated network of 

 ridges and knolls, so deposited by the ice as to form in- 

 numerable kettle-holes which are filled with water where 

 other conditions are favourable. Those which are dry are 

 so because of their elevation above the general level, and 

 of the looseness of the surrounding soil ; while many have 

 been filled with a growth of peat, so that their original 

 character as lakelets is disguised. 



As already described, these depressions, so characteris- 

 tic of the glaciated region, are, in the majority of cases, 

 supposed to have originated by the deposition of a great 

 quantity of earthy material around and upon the masses 

 of ice belonging to the receding front of the glacier, so 

 that, when at length the ice melted away, a permanent de- 

 pression in the soil was left, without any outlet. 



To some extent, however, the kettle-holes may have 

 been formed by the irregular deposition of streams of wa- 

 ter whose courses have crossed each other, or where eddies 

 of considerable force have been produced in any way. The 

 ordinary formation of kettle-holes can be observed in prog- 

 ress on the foot of almost any glacier, or, indeed, on a small 

 scale, during the melting away of almost any winter's snow. 

 Where, from any cause, a stratum of dirt has accumulated 

 upon a mass of compact snow or ice, it will be found to 

 settle down in an irregular manner ; furrows will be formed 

 in various directions by currents of water, so that the melt- 

 ing will proceed irregularly, and produce upon a miniature 

 scale exactly what I have seen on a large scale over whole 

 square miles of the decaying foot of the great Muir Glacier 

 in Alaska. The effects of similar causes and conditions 

 we can see on a most enormous scale in the ten thousand 

 lakes and ponds and peat-bogs of the whole glaciated 

 area both in North America and in Europe. 



In addition to these two lines of evidence of glacial 

 action in New England, we should mention also the in- 



