Further, the presence of early man close to the time and even the edge of the retreating glaciers—if the evidence is read aright—argues that he must have arrived in North America during one of those retreats of the Wisconsin glaciation which preceded its final growth and decline.
All this is speculation, of course—reasoned speculation, but no more than that. Are we on firmer ground when we deal with geological evidence? Perhaps, yet there is plenty of room for controversy.
The New World has very few sites in which artifacts or human bones have been found in glacial gravels. A noted one, near Trenton, New Jersey, has been under dispute for eighty years. The Lake Lahontan site and its blade have been too much neglected. There are, however, a number of places where skulls or artifacts have been found linked to other strata than gravels that suggest a relationship with glacial activity.
In these sites we find human skulls or artifacts together with signs of much rainfall or of large lakes and rivers which now have no more existence than the mammoth. The evidence of man lay undisturbed beneath sterile layers of material deposited by water. A typical case is Sandia Cave. Here Folsom points were found beneath a floor of a stalagmitic limestone created by so heavy a seepage of calcium-charged water that the stratum holding the Folsom material had been partially consolidated. Below lies another sterile layer—of yellow ocher earth, indicating a very moist period and the presence of trees which would provide certain chemical agents and which are no more common now in this arid area than are heavy, continuous rains. Another example of mans association with a much moister time than the present comes from the cave in Brazil where the Confins skull was found. The skull lay under six feet of alluvial soil carried in by water. Later a layer of stalagmitic limestone sealed the sepulcher. It may be presumed that artifacts found on the shore or in the clay of Lake Cochise, Lake Mohave, and Pinto Basin—now dry and gone—must have been made during a time of great waters.
What do such evidences of unusual moisture mean? They mean that the men of these sites lived before or during a period of heavy rainfall not known there for at least the last 9000 years. Beyond that bare fact, debate begins. Walter, Cathoud, and Mattos, who described the Brazilian find, took a most conservative attitude and wrote that Confins man lived “a few thousands of years ago.”[27] Bryan, who studied Sandia Cave, placed the later wet period after the end of Pleistocene, or Great Ice Age, and the first wet period—along with the Sandia points—in the Late glacial.[28]