Photographer: Tyler Childress, U.S. Geological Survey
Native Americans of the Miwok tribe in the northern Sierra Nevada, Calif., were one of the first groups to move from a hunter-gatherer activity to manufacturing, producing salt for trade.
New U. S. Geological Survey research indicates that more than 350 basins three to four feet in diameter are carved in granite in an area the size of a football field, and that they were intentionally created by this tribe for the purpose of refining salt from a nearby salt spring.
“The water was carried to the individual basins, probably in water-tight baskets, where it dried in the summer heat, leaving a salt residue on the basin floor,” said Jim Moore, USGS geologist and co-author of the report. “Such a large enterprise produced far more salt than was needed by the local tribe for cooking, preserving food, and attracting animals for hunting, and they had a large surplus of the valuable item left over for trade with other tribes.” -- more