Bowman — Geologic Relations of the Guzco Remains. 321 



most of two glacial series. The coarse deposits and not the 

 lower fine deposits have intimate relations with glacial material 

 in the higher valleys. Therefore the coarse deposits were 

 formed at the time of the last glaciation. Although two 

 periods of glaciation may be identified throughout the Central 

 Andes, I have nowhere been able to find any evidence of great 

 differences of age. The lower, finer, eroded deposits appear 

 to be in as fresh a condition as the overlying coarse material 

 both at the contact and below it. This suggests that the 

 deposits may correspond to those of the earlier and later Wis- 

 consin glacial stages, the last in a series of six glacial epochs 

 of which evidence is found in central North America. 



The topographic and drainage relations that in the United 

 States have made it possible to estimate the age of the deposits 

 of the last glacial invasions, and indeed of some of the earlier 

 ones, are not duplicated in the Central Andes ; nor have I 

 been able to find other relations that will serve the same pur- 

 pose. Estimates of the age of glacial deposits in South America 

 rest upon comparison with glacial deposits in the northern 

 hemisphere and the conclusion that glaciation was contempo- 

 raneous in the two hemispheres ; in other words, that the cli- 

 matic conditions which produce glaciation are of cosmic origin. 

 Although I have studied the glacial deposits of the Central 

 Andes in a great variety of climates and have examined glacial 

 deposits in six of our northern states and in Canada, I can see 

 no essential difference in the degree of weathering. The 

 striking feature in all cases is the freshness of the material and 

 the comparatively youthful, in many cases merely incipient, 

 erosion of glacial forms. Direct evidence of contemporaneity 

 has been presented by Steinmann." In a later paper the 

 writer will present a new line of evidence in support of the 

 same conclusion. 



If we take contemporaneous glaciation in the northern and 

 southern hemispheres as the basis for further consideration, we 

 shall have as the age of the older deposit of the first epoch 

 40,000 to 150,000 years and the age of the later coarse deposits 

 in which the Cuzco man was found as 20,000 to 60,000 years. 

 The layers in which the bones were found do not lie higher 

 than midway in the coarser series ; I should be inclined, were 

 it not for the remains in them, to place them in the lower half 

 of the coarser series, which would give them 40,000 to 60,000 

 years. f A conservative statement then is that the bones 

 appear to be from 20,000 to 40,000 years old, or that they have 



*Uber Diluvium in Siid-Amerika, von G. Steinmann, Sonder-Abdruck 

 aus den Monatsberichte der deutschen-geologischen Gesellschaft, Jahrg. 

 1906, Nr. 8/10. 



fSee Chamberlin and Salisbury, Geology, vol. iii, 1906, p. 420. 



