CARBON- 14 AGE DETERMINATION — F. H. H. ROBERTS 343 



name Yuma. The latter became somewliat of a catch-all designation 

 for points that could not otherwise be identified and has more or less 

 been replaced by specific site names. The first points of this type 

 were believed to be contemporaneous with Folsom, but subsequent 

 work showed that their contemporaneity at best was a very late one 

 and that they more likely actually represented a subsequent horizon. 

 In this category are specimens such as those found by Dr. G. L, 

 Jepsen, of Princeton University, at Sage Creek in Wyoming. The 

 average date for that material, derived from partially burned bison 

 bones, is 6,876 ±250. Other specimens falling in the same category 

 were found in a site at the Angostura Reservoir in South Dakota. 

 Charcoal found at the occupation level tested 7,715 ±740, while simi- 

 lar material taken from an oval-shaped unprepared hearth dated 

 7,073 ± 300. Geologic studies at both of those locations have not yet 

 been completed so it is not known what the conclusions are with re- 

 spect to their geologic age. 



Caves in the Humboldt Valley in Nevada have furnished speci- 

 mens that have been dated 7,038 ±350 years, 5,737 ±250 years, and 

 2,482 ±260 years. These dates were obtained from bat guano and 

 archeological artifacts. In the cave containing the oldest objects, the 

 guano layer below the artifact-bearing stratum rested on Pleistocene 

 gravels and, as previously mentioned, material from the contact tested 

 11,199 ±570. Briefly, the evidence there shows that man was present 

 in that district by 5000 B. C. and that the region was occupied 

 during the dry Altithermal Period of 4000 B. C. After approxi- 

 mately 1,500 years' occupation the region apparently was abandoned 

 until about 500 B. C. from which time there is an unbroken archeo- 

 logical record to the present day. The oldest date thus far for Cali- 

 fornia is 4,052 ±160, but since Olivella hiplicafa shell beads were 

 found at the 7,000-year-old level in one of the caves in Nevada, it 

 seems evident that there must have been people along the Pacific 

 coast at that time (Heizer, 1951). 



In southeastern Arizona a series of cultural horizons designated 

 the Cochise yielded carbon-14 dates of 7,756±370 and 6,210 ±450 

 for the oldest stage. The next or second stage yielded dates from 

 4,508 ± 680 to 4,006 ± 270, while the third stage gave 2,463 ± 310. From 

 these dates it is obvious that the sequence of the three stages which 

 was established on geologic and typological evidence was sound. The 

 dates themselves, however, are somewhat lower than previous esti- 

 mates based on climatological studies, particularly in the case of the 

 first period which is about 2,000 years younger (Sayles and Antevs, 

 1941). The carbon-14 figures indicate that, contrary to the opinion 

 of many, the Cochise peoples had not moved into that area prior to 

 the appearance of hunting peoples of the Folsom type in the region 



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