First Americans

Anthropologists tell time in large, round numbers. When their clocks and calendars go wrong, their calculations go wrong in a big way. Man's arrival in North America, for example, says Johns Hopkins Professor George F. Carter, has been misdated by an interglacial age or two--a mistake of perhaps 300,000 years.

Until Dr. Carter corrected the anthropological calendars in the winter issue of the Southwestern Journal of Anthropology, most of his colleagues thought man discovered the North American continent late in the last ice age, 10-20,000 years ago. Arctic hunters, so the theory ran, followed game across the top of the world. They ranged southeastward from Siberia, carrying their stone knives at least as far as what is now Folsom, N. Mex.

After two decades of digging in the road cuts and river beds of Southern California, Anthropologist Carter has made a collection of chipped stone artifacts, so crude that even Folsom man would have sneered at them. Although they look like broken cobbles from some wave-eroded beach, Dr. Carter is sure his ancient stones were flaked and shaped by man. The broken edges, he says, are the result of sharp blows from primitive stone hammers.

To place the rude tools properly on a prehistoric calendar, Dr. Carter first analyzed the chemical content of the soil in which they were found. It dated back to humid-glacial times. Then he located the sandy terraces where California's rivers deposited their silt and gravel between the periods when four great glaciers moved south from the Pole.

As each glacier advanced, the sea level dropped. Rivers cut deeper into the soil leaving distinct terraces along their flanks. When the glaciers melted, the sea level rose, but never quite as high as it had been before. After succeeding waves of ice, the coastline expanded still farther and rivers cut deeper terraces as they washed toward the sea. Dr. Carter found his artifacts where the roads and gravel pits around modern San Diego have uncovered the terraces formed some 2,000 centuries ago, between the earth's third and fourth glaciers.

The early slopeheaded settlers may have crossed from Asia to Alaska even as the third glacier began to flow, thinks Dr. Carter. If so, they probably pushed south along a narrow coastal corridor while they hunted fish and shells. And, more than 3,000 centuries ago, they were squatting by their river camp sites, chipping the tough California rock into crude weapons.

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