No. 5.] SPENCER — SURFACE GEOLOGY. 287 



this glacier at 20,000 feet, at the pole) and the abstraction of 

 that amount of water from the sea would lower the sea-level 

 over the whole globe about liOO feet. The snow cap necessary 

 to lift drift material over Mount Washington would so much ex- 

 ceed this thickness as to increase the improbability. Nor does 

 it seem possible that any local glacier in the White Mountains 

 could, even if it had a sufficient thickness to produce its own 

 flow, lift drift materials several hundred feet higher than the 

 place whence they came, and not sheer off on the lower ice and 

 pass around the high peaks — a constant requirement of the 

 glacier hypothesis. 



It is not my purpose here to attempt to discuss the ice cap 

 in the White Mountain regions. Yet it is necessary to refer to 

 this region on account of the sreat elevation of drift material, in 

 looking out the causes of the drift in the region of Lake Ontario. 

 The local evidence of moraine-Jbrmed dams does not seem suffi- 

 cient to counteract the seeming impossibility above pointed out. 



I'ransportation hy Coast Ice. — The floating ice theory here 

 answers much better than that of the iilacier, for on the conti- 

 uent sinking the ruins of the hills of lower levels could be carried 

 upward by the action of coast or pan ice of successive years, 

 which along the Restigouche and St. Lawrence rivers has been 

 known to move enormous blocks of rock to a considerable dis- 

 tance in a single season. The great precipitation of snow about 

 the North Atlantic, along the ranges of American mountains 

 bordering it, would tend to depress the north-eastern portions of 

 the continent more than either those to the southward or west- 

 ward. This depression was nearly 2,000 feet, at least in the 

 later Terrace epoch of the Ice Age, beyend the Western End of 

 Lake Ontario. In the mountain regions of the Pacific coast 

 the evidence of a subsidence to more than 4,000 feet is ap- 

 parent. 



At the northern end of Skaneateles Lake in New York we 

 find, at an elevation of 860 feet above the sea, Corniferous lime- 

 stones, which belong to rock beds hi situ at only lower levels to 

 the northward. These apparently were lifted upward by floating 

 ice during the subsidence of the region. Again, at the Western 

 End of Lake Ontario, we find great quantities of water-worn 

 pebbles, whose original rock lies thirty or forty miles away, but 

 at only lower topographical levels, except a great distance away. 



Terminal Moraine Hypothesis. — Another evidence strongly 



