GLACIAL EROSION AND TRANSPORTATION. 259 



depth is equally great. In the upper valley of the South 

 Saskatchewan, at an elevation of about 4,000 feet above the 

 sea, and from 600 to 700 miles west of the Laureutian axis, 

 from which much of the glaciated material came, Mr. McCon- 

 nell reports sections of till 125 feet deep.* 



Professor Stone thinks the average thickness of the drift- 

 in Maine is between thirty and fifty feet. Mr. Upham's 

 early calculations for New Hampshire were much more mod- 

 erate, namely, ten feet.f But he now informs me that he 

 would make a much higher estimate. Besides, in so mount- 

 ainous a district, we should expect a thinner deposit to re- 

 main on the surface. The more rapid streams would trans- 

 port a larger portion of the material to the sea than from the 

 gentle slopes. Furthermore, the rocks of New Hampshire 

 are better calculated to resist erosion than in some other por- 

 tions of the country. Much of the soil of New Hampshire 

 has been transported to the States farther south. No re- 

 liable estimate has been 'made of the average depth of 

 the glacial accumulations over Massachusetts, Connecticut, 

 and Rhode Island. There can be little doubt, however, that 

 it is much greater than Mr. Upham makes for New Hamp- 

 shire. 



Professor Shaler % sets down the total amount of drift in 

 New England and its neighboring terminal moraines at 750 

 cubic miles, or more than the mass of the White Mountains. 

 If evenly distributed, this would make a layer of about sixty- 

 five feet. 



Professor Lesley says the depth of the glacial drift over 

 the northeastern counties of Pennsylvania is not less than 

 fifty feet. This is on the summit of the Appalachian plateau, 

 while the old valleys, filled with glacial debris, are some of 

 them of great depth. One on Mehoopany Creek, in Wyo- 

 ming county, is filled with drift to a depth of more than 235 



* " Report of the Cypress Hills," 1886. 



f "Xew Hampshire Geological Report," vol. in, p, 293 



\ "Illustrations of the Earth's Surface: Glaciers," p. 58 



