HARTVILLE WYOMING — Upon their arrival in the late 19th century, settlers in the Hartville area found a landscape pocked with pits, craters, trenches, and tunnels and littered with reject material. The massive nature of the excavations led to the assumption that Spanish conquistadors prospecting for gold were responsible, hence the name “Spanish Diggings”.
The area attracted the attention of the Bureau of American Ethnology, the Field Museum of Chicago, and later the National Geographic Society and University of Wyoming. Scientists who visited the area quickly debunked the Spanish myth and realized that the extensive excavations were the result of stone quarrying by Native Americans, in search of high quality toolstone.
Spanish Diggings extends from modern day U.S 26 on the south to U.S. 18 on the north, and from I-25 on the west to U.S. 85 on the east. It encompasses much of what geologists recognize as the Hartville Uplift. This is a structural arch in which Pre-Cambrian, Paleozoic, and Mesozoic rocks were uplifted during the Laramide Orogeny.
Though much of the uplift has been buried by younger sediments, extensive exposures of several Paleozoic and Mesozoic formations which contain extremely high-quality cherts and orthoquartzites are common. Fine-grained purple, gold, grey, tan and red orthoquartzites occur in the Morrison-Cloverly formations, and several cherts (often a butterscotch color with black dendrites) can be found in the Mississippian age Guernsey and Hartville formations.
Native Americans went to extraordinary efforts to mine these exposures for the highest quality material, leaving tons of reject material in their wake. Stone wedges, hafted and unhafted hammerstones, bone and antler served as digging implements. Once blocks were removed, preliminary flaking to shape cores, blanks and performs which were then transported away from the quarries for future use happened. Thousands of domestic structures and camps throughout the Hartville Uplift also illustrate the extensive use of the area.
Artifacts made from Spanish Diggings quartzites and cherts have been found across Wyoming and throughout the Northwestern Plains. Native Americans quarried materials in the Hartville Uplift during Paleo-Indian times (ca 12,000 years ago) and continued mining until the Historic Period. Large ceremonial bifaces made of Mississippian age cherts, possibly from the Spanish Diggings, have been found in Hopewell burial mounds as far away as LaCrosse, Wisconsin. This find points to the important role the Spanish Diggings quarries played in the economic and social aspects of Native American cultures for thousands of years.
