The U.S. Department of the Interior, U.S. Geological Survey, reports its conclusion that Native Americans of the Miwok tribe in the northern Sierra Nevada mountains in modern-day California were one of the first native groups to move from a hunter-gatherer activity to manufacturing. The Survey says the Miwoks produced salt for trade.
According to U. S. Geological Survey research, it found more than 350 basins three to four feet in diameter carved in granite in an area the size of a football field, and intentionally created by the tribe for the purpose of refining salt from a nearby salt spring.
Jim Moore, USGS geologist and co-author of the report, said: “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.”
Making the basins was challenging and required concerted effort by this group of Native Americans, though the exact techniques used to excavate so many basins in this glaciated bedrock are not known.