The earliest culture of the Western Hemisphere, about which we have any information, is the _Sandia_,[64] so named because the cave whose deposits showed that it had been occupied by men about 25,000 years ago is located in the Sandia Mountains of New Mexico. In the bottom layer of this cave were found fairly large, crudely flaked stone spear points with a more or less leaflike shape and a slight basal inset on one side. With these points were found bones of prehistoric horse, bison, camel, mastodon, and mammoth, probably the debris from meals of ancient hunters who lived in the cave. Space does not permit a detailed consideration of the geological studies[9] which enable us to assign a date to this early occupation, but above the layer in which the Sandia points were found there were other layers which included one of calcium carbonate and one of yellow ochre. Geologists can interpret the climatic conditions under which such deposits were formed and they have correlated them with geologic periods when such conditions prevailed. Great humidity, such as is indicated by the Sandia Cave deposits, is characteristic of certain areas during glacial stages and the lowest level of Sandia Cave has been assigned to the period preceding the last major ice advance in the Pleistocene Period or Ice Age. This glaciation is believed to have occurred about 25,000 years ago. Folsom The most famous of the ancient cultures is the _Folsom_ whose name is derived from the town of Folsom, New Mexico, near which the first generally accepted American discovery of man-made objects associated with the bones of extinct animals was made.[25] Prior to this find, which was made in 1926, it had been believed that man had not reached the New World more than a few thousand years before the beginning of the Christian era. At the Folsom site, however, were found finely flaked projectile points in clear association with the articulated bones of a type of bison known to have been extinct for many thousands of years. These were fluted or grooved points characterized by the removal of longitudinal flakes from either face. Geological evidence from the Lindenmeier Site in Colorado, which was a camp site of the makers of the grooved points, indicates that the Folsom people lived between 10,000 and 25,000 years ago.[11] This conclusion was reached by correlating the valley bottom in which the site occurs with river terraces and moraines, which in turn could be related to glacial stages. A number of important discoveries of fluted points have been made in the Southwest. Two notable sites are the one near Clovis, New Mexico, and Burnet Cave in the Guadalupe Mountains.[65] [Illustration: Fig. 2—Map of the Southwest showing sites referred to in Chapter II.] 1. Burnet Cave 2. Clovis 3. Cochise sites 4. Folsom 5. Gypsum Cave 6. Lindenmeier Site 7. Sandia Cave 8. San Jon 9. Tabeguache Cave 10. Yuma