Trout Creek in east Chaffee County is an extensive archaeological site exhibiting natural outcrops of colorful jaspers that were used for thousands of years as raw material for toolmaking by many different groups of Native Americans. It is one of the best-known toolstone sources not only in central Colorado but in the whole of the Southern Rocky Mountains. Archaeologists have surveyed and documented rock outcrops, quarry pits, and workshop debris spread over more than 1,000 acres south of Trout Creek Pass on both private and public lands.

Geologic Context

Outcrops at Trout Creek are mostly yellow brown to dusky red chert, often with black, green, or red inclusions. The rock can be described as a dendritic jasper—an iron-rich chert—because of the common presence of green to black lines in intricately branching patterns. Some Trout Creek materials have inclusions that are not dendritic forms, while others are solid colors lacking any patterning. Recent geologic mapping found that the material occurs in blocks of late Eocene or Oligocene age (23 to 38 million years old), whose movement slid sections of much more ancient rock northward down toward Trout Creek. A preliminary study in the 1980s identified the host rock as the Manitou formation, which is Early Ordovician (470–85 million years old) limestone and dolomite. More recent fieldwork suggests that some of the jasper also may occur in the Fremont dolomite of Middle and Late Ordovician age (443–70 million years old).

Prehistoric Activities

Artifacts found in the workshop areas and in the surrounding region show that people used Trout Creek jasper throughout the prehistoric era, beginning in the Paleo-Indian period at least 10,000 years ago. Because jaspers and other cherts are quite durable and fracture into sharp-edged fragments, flintknappers were able to make many different kinds of tools, including spear points and arrowheads, knives, scrapers, drills, and choppers. Other artifacts not made from the local jasper were brought to the site to meet other needs, such as seed-milling tools and a few ceramic containers.

Although no evidence of ancient houses has been found at Trout Creek, smaller prehistoric features have been documented. These include several campfire pits and one somewhat different burned pit interpreted as a “heat-treatment” feature. When certain rock types, such as chert and jasper, are buried in shallow pits and then baked for several hours, the result is rock that is more brittle but fractures with even sharper edges than unheated rock. In effect, toolmakers were sacrificing the durability of the rock to create material that was easier to shape and provided sharper cutting edges.

The Trout Creek Source Zone

After decades of research, archaeologists now know that many other jaspers occur in the same general region as the Trout Creek source, especially to the south in the Arkansas Hills, and eastward into South Park. At last count, twenty-seven separate sources of jasper have been documented beyond Trout Creek, even though less than 10 percent of this area has been inventoried. Some of these materials have dendritic inclusions visually similar to Trout Creek, and artifacts made from them may be erroneously assumed to be from Trout Creek. There are other such “source zones” known to archaeologists in the American West, such as in western North Dakota and the Texas Panhandle, but these are the exception rather than the rule. Clearly, there is much more to be learned about this part of Colorado that was so heavily frequented by Native Americans. It is quite likely, however, that the Trout Creek site is the largest and most intensively utilized source in the region.