384 CLIMATIC COXDITIOx\S OF THE GLACIAL EPOCH. 



Much the same difficultj- is experienced in making out that the White 

 Mountains or the Adirondacks have ever been passed over by an ice sheet 

 coming from the north. Vanuxem and Emmons assert that in the latter 

 range the glaciation, as well as the distribution of the boulders, was from the 

 centre in a radiating direction, and it is not known to the writer that this 

 statement has been proved not to be correct. In the White Mountains the 

 evidences of the descent of local glaciers from the higher regions towards 

 the lower are very perceptible ; the proof that the range has been buried 

 nnder an ice sheet thousands of feet in thickness is not — to the present 

 writer — by any means satisfactory. 



The discovery of water-worn pebbles and boulders on or near the summit 

 of Mount Washington cannot be accepted as evidence that a continental 

 glacier has been there. To assume such to have been the case is simply 

 another instance of the prevailing delusion that fragments of rock cannot 

 be rolled and transported by water. A good illustration of the fact that the 

 discovery in question is not satisfactory evidence of the former presence of 

 ice is found in the isolated patches of gravel occurring on Clermont and 

 Spanish Peak in the Sierra Nevada. These detrital deposits might as well 

 be ascribed by the enthusiastic glacialist to the agency of a continental gla- 

 cier as those observed on Mount Washington. But in the case of the C;ili- 

 fornian mountains we are sure that ice had nothing to do with the occurrence 

 of the gravel where Ave find it. We know that these patches are fragments 

 of old river channels, the evidence to this effect being abundant and con- 

 vincing. The traces of a past luxuriant vegetation buried in the finer layers 

 interstratified with the gravel are sufficient jsroof that this deposit was not 

 made in the presence of ice. 



Whenever the striation of any particular mountain region has been care- 

 lully studied, it has almost always been the case that the phenomena have 

 been found to be of a much more complicated nature than had Ijeen previ- 



again farther on. At the request of the writer, Professor Hamlin has furnislied the following statement, in which 

 are embodied conclusions based on observations made since the publication of the paper mentioned above : "The 

 thin and lilade-like form of that portion of Ktaadn upon which the two peaks are situated seems incompatible with 

 the hypothesis that a moving ice-sheet has covered tlie mountain to its summit. Ijower down than the highest of 

 those flatter parts where scanty fragments of loose stratitied rock occur, are several sharp crests having such direc- 

 tions that the supposed ice-sheet must have passed over them transversely. The continuance of such ridges to the 

 present time, the fact that in my explorations of ISSl I found the lower northern extremity of Ktaadn to be 

 bounded liy steep cliffs or highly inclined faces, ami the entire absence of surfaces approaching the condition ot 

 roches moutonnies, taken together, forbid to my mind the conclusion that Ktaadn has ever been, on its lower slopes 

 or .summit, acted upon liy a continental ice-sheet." 



