308 Bowman — Geologic Relations of the Cuzco Remains. 



geology of the upper Cuzco basin with special reference to 

 glacial forms, it is concluded (1) that the beds belong to a 

 glacial series, (2) that the bones were deposited during a period 

 of pronounced alluviation, and (3) that since the deposition of 

 the bones from 75 to 150 feet of gravel were deposited over 

 them and later partly eroded. The age of the vertebrate 

 remains may be provisionally estimated at 20,000 to -±0,000 

 years. 



The weaknesses of the case lie in the following facts : (1) 

 Certain vertebrate remains* found associated with the human 

 bones may be referred to bison, but they are not sharply dif- 

 ferentiated from the bones of modern cattle. Bison remains 

 have not been found either in other places in the Central 

 Andes or . elsewhere in South America. The distinctions 

 between these fragmentary bones and those of modern cattle 

 are not sufficiently well-marked to enable one to say absolutely 

 that they could not be bones of domesticated cattle. Further- 

 more, certain canine bones gathered in connection with the 

 human remains cannot be said to be unlike those of the 

 modern domesticated dog. While both these pieces of evidence 

 are negative in character and do not actually disprove the case, 

 they raise wholesome doubts that can not be dispelled save by 

 further Held Avork, especially excavation. (2) In the second 

 place, there is one untested possibility and until that test is 

 applied the case cannot be said to be proved absolutely. It is 

 within the limits of possibility, although it still seems very 

 unlikely, that the bluff in which the bones were found may be 

 faced by younger gravel and that the bones were found in a 

 gravel veneer deposited during later periods of partial valley 

 filling. Until excavation is carried on, the interpretation must 

 rest, not upon all the facts, as X, but upon X-l facts. Indeed 

 excavation may show that the facts in hand are really X-2 or 

 X-3 in number. 



Criteria. 



In determining the age of buried human remains account 

 must be taken of two guiding principles : 



(1) The remains and the beds in which they are found must 

 be proved to be contemporaneous. 



(2) The age of the beds must be determined by independent 

 means. 



The possibility of landslips, of recent changes in the beha- 

 vior of streams, and of burial by human hands or by ani- 

 mals, must be considered in minutest detail. This is forced 



* For both the nature of the vertebrate material and the characteristics 

 of the individual bones see the report by Dr. George F. Eaton in this number 

 of the Journal (p. 325). 



