M. Charpentier on the Erratic Fhcuoimna of the North. 73 



the manner in which I conceive this great phenomenon to 

 have been caused, it must suffice, I think, to shew that the hy- 

 nothesis of 1\I. Venelz, combined to a certain extent with that 

 of floating ice, accounts for it better than that which attri- 

 butes it to an enormous current, coming from the polar re- 

 gions, and which, at the same time, assigns too important a 

 part in the operations to floating ice. This latter hypothesis, 

 apart from the improbabilities which it presents, is, even in 

 the opinion of its defenders, insufficient to explain many facts 

 that are of importance, and are connected with the erratic 

 phenomenon ; it thus leaves us in doubt and in uncertainty. 



Permit me. Sir, to terminate this long letter by giving, in 

 a few words, a summary of the principal ideas which I have 

 now offered : — 



1. In consequence of the last gi-eat catastrophe which 

 altered the conflguration of the surface of the northern hemis- 

 phere over a vast extent, the climate became colder and 

 moister than it was previously, or is at the present day. 



2. During the long continuance of this climatological con- 

 dition, the summer temperature was insufficient to melt com- 

 pletely the snows from the 60th parallel. 



3. The snows comprised between the GOth and 70th paral- 

 lels were transformed into glaciers. Beyond the 70th paral- 

 lel they remained in the state of neve. 



'4. This glacier having acquired a considerable development, 

 invaded the north of Russia as far as Moscow, Prussia, Poland, 

 the north of Germany, and perhaps the eastern shores of 

 England. 



5. It transported and deposited the erratic formation, and 

 produced marks of abi'asion, the strias and furrows which have 

 been observed on rocks. The cascades to which it gave rise 

 have caused the erosions in the form of caldrons. 



6. The most southern accumulations, having the form of 

 mounds or bands, are the moraines which it deposited during 

 the maximum of its development. 



7. Osars are moraines, some having been formed by the 

 oscillations to which the great glacier was subjected during 

 its retreat, others by the ice which remained on elevated 

 mountains and table-lands, long after the low regions had been 

 freed from it. 



