Prehistoric Mining in the High Mountains of Northern Colorado

Summary

Rupturing and buckling of fissures along the present valley of the Colorado River in Middle Park, Colorado, during the Miocene resulted in thick deposits of tuff and flow basalt which resulted in the Troublesome Formation. The Troublesome Formation primary consists of weakly consolidated siltstone, minor interbedded sandstone and conglomerate, and locally unconsolidated sand and gravels, and chalcedonies. As the result of the chalcedony filtering through the tuffaceous linear deposits of jasper immediately beneath the tuff were formed. The Granby Site (5GA151) is a prehistoric mining site, whose knowledge of the area has been passed down for at least 11,000 years, from Goshen to Ute. The location of the mining site on the toe of a basalt flow that has been tilted by tectonic forces brought three deposits of jasper to the surface enabling the material to be mined. A recent project on the Granby Site enabled the site to be studied and to identify numerous purposely shaped "tabs" of jasper. These tabs enabled easy transport of the mined material away from this high altitude mine. The jasper material was traded up and down the Colorado River valley and became a major source of tool stone for over a millennia.

This Resource is Part of the Following Collections

• Society for American Archaeology 82nd Annual Meeting, Vancouver, BC (2017)

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Record Identifiers

Abstract Id(s): 15295