328 SURFACE GEOLOGY. 



in ice-walled ravines, could not have taken many years for their accumu- 

 lation; and if the higher terraces are remnants of the immediately suc- 

 ceeding freshets, there is no reason to believe them long continued. Fol- 

 lowing out the analogy of seasons as already commenced, this should be 

 compared with the spring freshets. These require very little time for 

 their rise, culmination, and termination, while they may occur at succes- 

 sively later and later points of time, as you pass from the mouth to the 

 source of the streams flowing southerly. 



The time when man was introduced is connected with the figures as- 

 signed for the termination of the glacial period. There seems no like- 

 lihood that our ancestors would have found the conditions of life favorable 

 to their existence among the glaciers, so that they would not have emi- 

 grated here from warmer latitudes before the Champlain period. No 

 certain evidence of man earher than the Champlain period has yet been 

 discovered in any part of the world. Hence there is little reason to be- 

 lieve he was introduced more than 40,000 years ago.* 



Recent Scotch authors insist upon a greater antiquity for man than 

 this, because his implements have been found in the inter-glacial beds, 

 thus carrying him back at least 100,000 years. The observations stated 

 above intimate the unreliability of the theory respecting the great antiq- 

 uity of these inter-glacial beds. Those in New Hampshire can all be 

 accounted for without assuming the intercalation of warm periods into 

 the glacial age. It would be ungracious to assume that our phenomena 

 should be taken as the standard of measure for those elsewhere; but as 

 very few other writers have perceived the distinction between the lower 

 and upper till, we desire to be informed whether their inter-glacial beds 

 cannot be referred to a place between the two kinds of drift, before ac- 

 cepting the Scotch conclusions. The use of astronomical calculations 

 in the determination of the duration and definite place of the glacial 

 period is of great importance, and if thoroughly proven will form a basis 

 for the establishment of a geological chronology, not merely for the latter 

 part of the Cenozoic, but of all time, even to the era of the Eozoon or 

 the simpler denizens of the Eophytic period. 



Mr. Upham has prepared some brief statements respecting the relative 



* This is given as the remotest possible date for the introduction of man. Other evidence might be pre- 

 sented illustrating the fact that very exaggerated notions of the great age of man prevail at the present day ; 

 but the subject has no connection with phenomena discovered in New Hampshire, and is therefore omitted. 



