At Tule Springs, in southern Nevada, for more than two decades, Southwest Museum archaeologists have periodically found evidence of what may have been man-made campfires and the broken, scorched, and scattered bones of camel, mammoth, bison, and perhaps horse and sloth. In 1956, Ruth D. Simpson located _in situ_ “a small uniface convex scraper, retouched along approximately two inches of its circumference” in a pocket of charcoal. From this charcoal, a date of more than 28,000 years was determined.[79] The few artifacts recovered at Tule Springs are rather nondescript, but ancient hunters surely occupied the site at various remote times. Burned bones of dwarf mammoths on Santa Rosa Island, off the Santa Barbara coast of southern California, have furnished radiocarbon dates ranging from 15,000 to about 30,000 years ago. The situation of these bones strongly suggests death at the hands of man. Sure association of cultural materials with the six-foot elephants has not been determined to the full satisfaction of archaeologists.[80] Although the indicated dates may be accurate—and it is not unlikely that these animals were hunted by early man—there are other explanations that are even more plausible. Near San Diego, California, exposed cliffs with alluvial deposits and raised sea beaches of presumed Pleistocene age contain burned places, or fire lenses, often as much as 100 feet across. George F. Carter believes these to be hearths dating back to third interglacial times or earlier.[81] As evidence of human occupation, he has assembled quantities of crudely chipped cobbles, described as “core tools.” His critics maintain that most are even cruder than the lower paleolithic hand axes of Europe, and refuse to grant that any of them were made by man.[82] Unmistakable artifacts, including types described as choppers, scrapers, and hand axes, have been found in abundance in the Mohave Desert, at Pleistocene Lake Manix[83]—now, like Pleistocene Lake Mohave, a dusty playa—and on ancient beaches in nearby Death Valley.[84] The geology of these sites suggests that they may be of Pleistocene age, but the artifact types and materials do not differ significantly from those associated with the Lake Mohave and Silver Lake cultures, for which dates of less than 10,000 years are considered probable. The desert regions of Western America have provided other sites of apparent Pleistocene age in which the artifacts are both simple and crudely made. While it is tempting to consider these as being truly ancient, we will have to know much more about them before we can be certain that they are more than the output of backward desert dwellers such as Father Baegert described for Baja California in early mission days.[85]