From exquisitely flaked Folsom spear points to the spectacular cliff dwellings of Mesa Verde National Park, among the most visible vestiges of Colorado’s Native American history are those crafted from naturally available rock. Archaeologists and others have documented nearly 1,000 places across the state with evidence of ancient Coloradans gathering rocks for toolmaking and wall construction.
The first people to settle in Colorado more than 13,000 years ago brought with them a stone tool technology that was millions of years in the making. Indeed, the oldest known stone tools were made in east Africa more than 3 million years ago. The long history the toolmaking craft prior to the settlement of North America meant that most native cultures in the American West shared a common set of implements. Nevertheless, these early peoples did put their own stylistic imprint on specific tools, such as the projectile points used to tip spears and arrows.
Identifying “Quarry” Sites
Useful toolmaking materials, sometimes called “toolstone,” can be found among all the major rock categories: igneous, metamorphic, and sedimentary. Toolstones gathered from bedrock outcrops, as is commonly seen in the mountains and on the Western Slope at sites such as Trout Creek, are said to derive from primary sources. Nonbedrock quarries are called secondary sources and have the potential to yield multiple rock types. Such secondary deposits can be found statewide, even on the open plains in the form of gravels in streambeds and of loose rock pavements called pediments, which cover many prairie surfaces near the Front Range mountain front.
Although these diverse sites are often called quarries, that label exaggerates the scale of “mining” that archaeologists typically encounter at prehistoric sites. In fact, actual pit excavations at ancient quarries are uncommon at best, documented at fewer than 10 percent of known sites. Far more typical was casual surface collection of nodules in gravel deposits and of blocks broken away from bedrock outcrops by natural forces. At both primary and secondary sources, archaeologists often find broken nodules of low-quality material, called tested cobbles, which suggests that native cultures engaged in a basic quality control equivalent to the modern-day mining practice of high grading—taking the best-quality material and leaving inferior materials behind.
In the earliest Colorado sites of the Paleo-Indian period, archaeologists have found artifacts made from high-quality materials gathered well beyond the state’s borders. For example, at the Clovis age Drake Cache in Logan County, eleven of the thirteen finely flaked spear points were made from a flinty rock type called chert that derived from a source zone in the Texas Panhandle, while one specimen came from an even more distant source area in central or west Texas.
As Colorado’s native peoples explored more of the state, they quickly homed in on more local toolstones of high quality. For example, the Mountaineer site of Folsom age has yielded thousands of stone artifacts made almost exclusively from locally available raw materials, including many items from a source high in the San Juan Mountains. Later toolmakers of the Archaic and Formative periods likewise preferred local Colorado rock types with the exception of glassy volcanic obsidian, which occurs in much larger quantities in the neighboring states of New Mexico, Utah, Wyoming, and beyond.
Late Paleo-Indian and Archaic period toolmakers expanded their use of local rock with the addition of sandstones and other coarse-textured materials needed mainly for seed milling equipment (manos and metates), among other tasks that required an abrasive surface. In the Formative period, this need skyrocketed particularly among the agrarian Ancestral Puebloans of the Four Corners region. Their sedentary village life and dependence on corn as a staple crop created even more of a need for blocky, abrasive rock—mainly sandstone—for use as manos, metates, and wall building, among other purposes.
Right Rock, Right Purpose
Decisions about which rock types best fit the needs of the toolmaker were based on several key criteria. Implements requiring a sharp edge or tip, such as knives and projectile points, could be made only from rocks that break in what is known as “conchoidal fracture,” in which sufficient force applied by a “flintknapper” at the correct angle near an edge produces sharp-edged pieces called flakes that can be used as is for simple cutting tasks. The toolmaker can then modify the flake or the nodule from which it was struck (called a core) into other needed implements. Among the rocks that break in this manner are chert, quartzite, basalt, petrified wood, and obsidian.
In selecting toolstones, artisans also sought out homogeneous rock samples without internal cracks or impurities and of a size fitting the tool’s purpose, from tiny, delicate items used for etching or piercing to large, heavy items used for pounding or chopping. For most tasks, toolmakers preferred more durable rock types that could withstand repeated uses before needing repair or replacement. An important exception was glassy obsidian, which is not at all durable but does break with an extremely sharp edge that was so favored that it became an important trade item. The texture of a rock’s surface also played a role in the selection process, with smoother types such as chert providing sharper edges while coarser sandstones and granites make better seed-milling tools.
Finally, the visual attractiveness or aesthetic quality of a rock was clearly part of the toolmaking story. Archaeologists find many artifacts crafted from truly beautiful gem-like materials that were not accidental choices. Many of the spear points in the Drake Cache are proof of this aspect of the toolmaker’s craft. Clearly, the most skilled flintknappers were able to impart an unmistakable artistic imprint to their products even as they created the functional tools they needed to help them survive and thrive.