holmes] 



ABOEIGINAL AMERICAN ANTIQUITIES PAET I 



69 



later Pleistocene by the physical geologist ; but this discrepancy is of no fur- 

 ther significance than an indication that the chronologies of paleontologist 

 and g(>()logist do not coincide. It suffices that the later episode of cold and 

 ^Yet in the I.ahdutan basin has been demonstrated by King, Gilbert, and Rus- 

 sell to correspond with the second ice invasion of the glacial epoch.* 



In a subsequent paragraph (pp. 306-307), speaking of the need of 

 careful discrimination and great caution in treating of exceptional 

 inclusions in unconsolidated geological formations, McGee makes 

 the following most instructive and important statement: 



It is a fair pi-esumption that any unusual oliject found within, or appa- 

 rently within, an unconsolidated deposit is an adventitious inclusion: Every 

 cautious field geologist 

 accustomed to the 

 study of unconsoli- 

 dated superficial de- 

 posits quickly leai-ns 

 to question the verity 

 of apparently original 

 inclusions ; he may, it 

 is true, exhaust the 

 entire range of hy- 

 pothesis at his com- 

 mand without satis- 

 fying himself that the 

 inclusion is adventi- 

 tious ; yet he is seldom 

 satisfied that he has 



exhausted the range of possible hypothesis as to the character of the inclusion, 

 and hesitates long before accepting any unusual association as verital)Ie. His 

 case is not that of the invertebrate paleontologist at work in the Paleozoic 

 i-ocks, to whom a single fossil may carry conviction; for not only are the possi- 

 bilities of adventitious inclusion indefinitely less in solid strata, but the mineral 

 character of the fossil is commonly identical with that of its matrix and so 

 affords inherent evidence of the verity of the association. Nowhere, indeed. 

 In the entire range of the complex and sometimes obsciu'e and elusive phe- 

 nomena of geology is there more reason for withholding final judgment based 

 upon imusua) association than in the unconsolidated superficial deposits of 

 the earth ; and it is only where there is collateral evidence that such testimony 

 is acceptable to the cautious student. Now, the sediments of Lake Lahontan 

 are generally, and in Walker River Canon almost wholly, unconsolidated and 

 so the probabilities are against the verity of the association. 



These considerations, although bespeaking nuich candor on the 

 part of McGee, do not make it imperative that an observation so 

 carefully made and recorded should be ignored by seekers after the 

 truth. Made by a geologist of high standing, it is the second most 

 important observation yet recorded bearing upon H\e ]n'oblems of 



Fig. 31. Terra-cotta figurine reported to have come from late Tertiary 

 or early Quaternary deposits, Idaho, (j) 



1 McGpe, An Obsidian Implement from Pleistocene Deposits in Nevada. 



