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U.S. Geological Survey Scientific Investigations Report 2009-5225

Hand-Hewn Granite Basins at Native American Saltworks, Sierra Nevada, California

By James G. Moore and Michael F. Diggles

ABSTRACT

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This site in the northern Sierra Nevada contains about 369 circular basins carved in fresh, glaciated granodioritic bedrock, with 325 basins crowded together in an area of 2,700 m2 on the main terrace. These terrace basins have a median average diameter of 125 cm (80 percent between 100 and 160 cm) and a median depth of 75–80 cm. They show a strong congruity to similar granitic basins in the southern Sierra Nevada apparently of Native American origin that are generally shallower.

The basins are not of natural origin, as indicated by uniformity in size and nonoverlapping character of the basins; their common arrangement in lineaments; details of the shape of the basins; features in common with granite basins in the Southern Sierra Nevada; and, most compelling, the clustering of all the basins adjacent to (within 20 m of) two saline streams fed from a nearby salt spring. Native Americans apparently excavated them for the purpose of collecting saline water to evaporate and make salt for their use, and also as an animal attractant and a trade commodity.

The flow of the salty streams delivers about 2.9 metric tons of salt per summer season to the basin area, and evaporation rates and the holding capacity of the basins indicate that about 2.5 tons of salt could be produced per season. This correspondence shows that the Indians made enough basins to exploit the resource. The site is the most impressive prehistoric saltworks yet discovered in North America and represents a unique departure from traditional hunter-gatherer activities to that of manufacturing.

The actual grinding of so many basins in granite could not have been done without the labor of a concentrated population. It is believed that the work was accomplished over a long time by many people and with the use of fire to help disaggregate the bedrock.

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Suggested citation:

Moore, J.G., and Diggles, M.F., 2009, Hand-hewn granite basins at Native American saltworks, Sierra Nevada, California: U.S. Geological Survey Scientific Investigations Report 2009-5225, 20 p.



Contents

Abstract

Introduction

Previous Work

Methods

Geology

Nature of the Granite Basins

Water

Strategy of Saltmaking

Salt-Making by Indigenous Peoples

The Case Against a Natural Origin for the Basins

Making the Basins

Future Work

Conclusions

Acknowledgments

References


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