288 THE ICE AGE IN NORTH AMERICA. 



the hills.* 3. They are not characterized by kettle-holes. 

 The surfaces are remarkably symmetrical, as if having been 

 smoothed over by design, and all the irregular depressions 

 are filled with homogeneous earth. 4. Up to one hundred 

 feet above their base, the flanks of these hills in Massachusetts 

 and New Hampshire are frequently covered with the water- 

 worn deposits hereafter to be described and known as kames, 

 and which are the very last work done by the ice at the 

 points where they are found. The drumlins are, therefore, 

 earlier than the kames. 



In structure these hills resemble the lower portions of till, 

 or the ground moraine. They are only imperfectly stratified, 

 and very compact, and filled with foreign and finely striated 

 stones. They are, without doubt, a true glacial deposit ; but 

 how comes the deposit to be heaped up in these localities in 

 such vast and shapely masses? Professor Shaler surmised 

 that they were but the remnants of a continuous ground 

 moraine which had been eroded from the whole country, 

 except where it was protected by pedestals or underlying 

 rock which served to break the force of the beating waves of 

 the ocean.f To this ingenious theory there are two fatal 

 objections : 1. Drumlins are frequently found where there 

 are no rocky pedestals to protect their bases. 2. They occur 

 in the interior far above any height to which it is supposed 

 the ocean has reached since the Glacial period. " The alti- 

 tudes at which they occur vary from the level of the sea to 

 fifteen hundred feet above it on the height of land between 

 the Merrimack and Connecticut Rivers." J Mr. Clarence 

 King would explain them as marking places in the great 

 continental glacier where streams of water which had run 

 for some distance in superficial channels along the surface of 

 the glacier and collected a great amount of debris from the 

 medial moraines, had finally plunged through a rnoulin into 



* " Proceedings of the Boston Society of Natural History," vol. xx, p. 223. 

 f Ibid., vol. xiii, pp. 196-233. 

 % Ibid., vol. xx, p. 233. 



