The North American Great Basin is an arid expanse that reaches from northern Mexico to southern Oregon. It is presently a land of desert shrubs and isolated mountain ranges separated by arid basins that often contain salt flats or parched clay pans. However, it was not always so. At times in the past it has been a brushy landscape spattered with lakes, large and small, and rich with animal life including extinct forms of bison, horses, camels, mammoths, and their predators. In most lowlands, some 15,000 years of Late Pleistocene and Holocene alluvial deposition has effectively buried and sealed earlier sediments and possible traces of a human presence in the region in Pleistocene time–the “Ice Age”–when tool-making humans were present throughout the Old World and when the Great Basin was not the desert it is today.
However, in the Manix Basin (Lower Mojave River Valley) of San Bernardino County, California, close by the Calico Mountains, a fortuitous combination of environmental factors have exposed a series of deposits that represent more than 350,000 years of Quaternary history. Within these deposits are rocks that, if found outside the Western Hemisphere, could easily be regarded as having been artificially modified to form stone tools, or lithic artifacts.
The obvious antiquity of the geologic deposits containing these objects has caused the most influential North American archaeologists to reject them as artifacts. They are rejected on the basis of where they are more than what they are. Consequently the objects have been regarded as geofacts: artifact-like forms produced by natural geologic processes. On the other hand, many European and Asian scholars familiar with Old World Paleolithic technology do indeed recognize many of the Calico specimens as authentic lithic artifacts, implying a human presence in the Americas for a span of time vastly longer than that generally accepted.
The following outlines the setting of the Manix Basin and presents the evidence for occupation of California’s Mojave Desert by tool-fabricating beings at a time equivalent to the classic “Stone Age” in the Old World.