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."

But how about the "bison"? Soon after his arrival in Cuzco, Dr. Eaton
examined the first ribs of carcasses of beef animals offered for sale
in the public markets. He immediately became convinced that the "bison"
was a P