Archeological resources are the primary—and often the only—source of information about humans in Yellowstone for nearly the entire time that people have been in the area. Archeological evidence indicates that people began traveling through and using the area that was to become Yellowstone National Park more than 11,000 years ago. Because the intensity of use varies through time as environmental conditions shift, archeological resources also provide a means for interdisciplinary investigations of past climate and biotic change.
Many thermal areas contain evidence that early people camped there. At Obsidian Cliff, a National Historic Landmark, volcanic glass was quarried for the manufacture of tools and ceremonial artifacts that entered a trading network extending from western Canada to the Midwest. These remnants of past cultures must be preserved, as they are invaluable in our understanding of early people in the area. Historic archeological sites in Yellowstone include the remains of early tourist hotels and army soldier stations.
Findings in Yellowstone
Although more than 1,850 archeological sites have been documented since the archeology program began in 1995, less than 3% of the park has been inventoried. Most documented sites are in developed areas because archeological evidence has been identified there inadvertently, or as part of National Historic Preservation Act compliance related to construction, hazard fuel reduction, or other projects.
Condition assessments performed on most of the documented sites found 1,013 were in good condition, 383 were fair, and 190 sites were in poor condition. Twenty-five of the sites no longer existed because of natural factors or disturbance as a result of construction or other authorized activity, and 238 lack condition data. Emergency excavations have been conducted at some sites where archeological remains are especially vulnerable to disturbance or loss through erosion or illegal collecting.
Multiple significant sites along the Yellowstone River have been nominated to the National Register of Historic Places. These contain projectile points or arrowheads, scrapers and other tools, and concentrations of burned and butchered bone, including the first evidence of fishing found in the park.
Radiocarbon dating is used to establish the age of organic artifacts such as charcoal or bone. However, organic materials (wood, bone, basketry, textiles) rarely persist in the Yellowstone environment because of the acidic, thermally influenced soils. Stone artifacts provide most of the chronological information on Yellowstone’s prehistory. Most of the stone tools that can be associated with a particular time period are projectile points. At Malin Creek, campsites from five distinct periods of indigenous use spanning more than 9,000 years are stacked upon each other starting at five feet below the surface. These occupations have revealed how tool manufacture and foodways changed over time.
The earliest evidence of humans in Yellowstone is an 11,000-year-old Clovis-type spear point found near the park’s north entrance in Gardiner, Montana, and made of obsidian from Obsidian Cliff. (Obsidian from different lava flows can be chemically fingerprinted using X-ray fluorescence analysis.) Later in time, point types increase in number and type, which may indicate that the number of people in the area was becoming larger as well as more diverse. Most documented sites in the park date to the Archaic period (8,000 to 1,800 years ago), suggesting that it was the most intense period of use by prehistoric people. Recent archeological surveys have identified a large number of sites dating to later periods in prehistory (approximately 1400–1800 CE). Distinguishing use of these sites by different ethnic groups or tribes, however, has not yet been possible.
Assessing Wildland Fire Impacts
Archeological resources can inform us about paleoclimate, paleoenvironment, and the human response to climate change over the past 11,000 years. Long-term climate data suggest current temperature rise and precipitation contribute to longer annual droughts and shorter wet seasons. Given changing environmental conditions, in 2016 the park embarked on a project to assess wildfire impacts on archaeological resources from the 2016 Maple Fire and Tatanka Fire Complex. Condition assessments have been completed for more than 70 sites, and analysis of data is ongoing. Preliminary results indicate sites subjected to intense heat and loss of vegetation are more susceptible to post-fire erosion, flooding, and other landscape processes which expose or threaten archeological resources.
Lewis and Snake River Headwaters Survey
In 2014, archeology staff completed an intensive inventory of 60 square kilometers of the Lewis and Snake river valleys, which served as major transportation corridors for many nomadic people. Newly identified sites include prehistoric quarries, campsites, and lithic scatters dating to between 10,000 and 1,500 years ago, as well as historic period quarries, campsites, and refuse dumps. The prehistoric sites are changing our understanding of how early humans procured stones and made them into tools. Most sites show heavy reliance on Obsidian Cliff materials and chert, a cryptocrystalline sedimentary rock. However, along the Lewis and Snake rivers a more diverse range of materials was used. Obsidian was primarily locally sourced from nearby Warm Spring, Teton Pass, and Park Point quarries, while orthoquartzite, a clastic sedimentary rock, was the most common material used for manufacturing tools.