CHAPTER VII. The Valley of the Huatanay
Dr. Eaton's study of the bones brought out the fact that eight of them were fragments of human bones representing at least three individuals, four were fragments of llama bones, one of the bone of a dog, and three were "bovine remains." The human remains agreed "in all essential respects" with the bones of modern Quichuas. Llama and dog might all have belonged to Inca, or even more recent times, but the bovine remains presented considerable difficulty. The three fragments were from bones which "are among the least characteristic parts of the skeleton." That which was of greatest interest was the fragment of a first rib, resembling the first rib of the extinct bison. Since this fragmentary bovine rib was of a form apparently characteristic of bisons and not seen in the domestic cattle of the United States, Dr. Eaton felt that it could not be denied "that the material examined suggests the possibility that some species of bison is here represented, yet it would hardly be in accordance with conservative methods to differentiate bison from domestic cattle solely by characters obtained from a study of the first ribs of a small number of individuals." Although staunchly supporting his theory of the age of the vertebrate remains, Dr. Bowman in his report on their geological relations admitted that the weakness of his case lay in the fact that the bovine remains were not sharply differentiated from the bones of modern cattle, and also in the possibility 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, ... although it still seems very unlikely."
Reports of glacial man in America have come from places as widely separated as California and Argentina. Careful investigation, however, has always thrown doubt on any great age being certainly attributable to any human remains. In view of the fragmentary character of the skeletal evidence, the fact that no proof of great antiquity could be drawn from the characters of the human skeletal parts, and the suggestion made by Dr. Bowman of the possibility that the gravels which contained the bones might be of a later origin than he thought, we determined to make further and more complete investigations in 1912. It was most desirable to clear up all doubts and dissolve all skepticism. I felt, perhaps mistakenly, that while a further study of the geology of the Cuzco Basin undoubtedly might lead Dr. Bowman to reverse his opinion, as was expected by some geologists, if it should lead him to confirm his original conclusions the same skeptics would be likely to continue their skepticism and say he was trying to bolster up his own previous opinions. Accordingly, I believed it preferable to take another geologist, whose independent testimony would give great weight to those conclusions should he find them confirmed by an exhaustive geological study of the Huatanay Valley. I asked Dr. Bowman's colleague, Professor Gregory, to make the necessary studies. At his request a very careful map of the Huatanay Valley was prepared under the direction of Chief Topographer Albert H. Bumstead. Dr. Eaton, who had had no opportunity of seeing Peru, was invited to accompany us and make a study of the bones of modern Peruvian cattle as well as of any other skeletal remains which might be found.
Furthermore, it seemed important to me to dig a tunnel into the Ayahuaycco hillside at the exact point from which we took the bones in 1911. So I asked Mr. K. C. Heald, whose engineering training had been in Colorado, to superintend it. Mr. Heald dug a tunnel eleven feet long, with a cross-section four and a half by three feet, into the solid mass of gravel. He expected to have to use timbering, but so firmly packed was the gravel that this was not necessary. No bones or artifacts were found - nothing but coarse gravel, uniform in texture and containing no unmistakable evidences of stratification. Apparently the bones had been in a land slip on the edge of an older, compact gravel mass.
In his studies of the Cuzco Basin Professor Gregory came to the conclusion that the Ayahuaycco gravel banks might have been repeatedly buried and reexcavated many times during the past few centuries. He found evidence indicating periodic destruction and rebuilding of some gravel terraces, "even within the past one hundred years." Accordingly there was no longer any necessity to ascribe great antiquity to the bones or the wall which we found in the Ayahuaycco quebrada. Although the "Cuzco gravels are believed to have reached their greatest extent and thickness in late Pleistocene times," more recent deposits have, however, been superimposed on top and alongside of them. "Surface wash from the bordering slopes, controlled in amount and character by climatic changes, has probably been accumulating continuously since glacial times, and has greatly increased since human occupation began." "Geologic data do not require more than a few hundreds of years as the age of the human remains found in the Cuzco gravels."