DRUMLWS. 289 



a deeply hidden subglacial river.* Here, it is thought, vast 

 cavities might be formed in which these accumulations would 

 take place, while, by the movement of the ice, the crevasse 

 might be transferred farther down, and so the accumulated 

 deposit be subjected to the pressure and sculpturing power 

 of the ice. 



Mr. Upham speaks on the subject as follows : " The finely 

 pulverized detritus and glaciated stones in the bottom of the 

 ice-sheet had a tendency to lodge on the surface of any de- 

 posit of the same material. When such banks of the lower 

 till became prominent obstacles to the ice-current, its level- 

 ing force was less powerful than this tendency of adhesion, 

 which continually gathered new material, building up these 

 massive rounded hills.'' t Mr. Upham remarks upon the par- 

 tial parallelism of these ranges of hills with the extreme ter- 

 minal moraine, and, with his usual perspicacity, notes that 

 both the glacial striae and the trend of the axes of the len- 

 ticular hills nearest the coast in Essex and Suffolk counties, 

 bear much more easterly than they do even a few miles in 

 the interior. This points with much force to the effect which 

 would be produced upon the movement of the ice near its 

 margin when it had receded a considerable distance from the 

 south, but especially from the east, where the waters of the 

 Atlantic had access to the glacier along the margin of what 

 is called the Gulf of Maine. When the waters of this gulf 

 had eaten the ice well away into the Massachusetts shore, and 

 thus removed the barrier to the east, the line of least resist- 

 ance would be in that direction, and the current would natu- 

 rally swing out toward the open sea. 



While recognizing the force of all Mr. Upham says, I can 

 not forbear repeating an additional suggestion of my own 



* I do not know a* Mr. King has anywhere published these views, nor, in- 

 deed, as he would now be willing to own them, as here stated. They were 

 given me in personal conversation, and contain so much that is worthy of con- 

 sideration, that I venture to repeat the theory. 



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



234. 



