Journeying through Time: Geology Meets Archaeology

Article courtesy of Association of Engineering and Environmental Geologists by Stefanie Voss


When we think about geology, it is usually in terms of environmental, engineering, seismology, and paleontology. How does archaeology fit in? For more than five years, I have been a part of the nonprofit group Cave Archaeology Investigation & Research Network (CAIRN). I serve as the group’s geologist. Susie Jansen and Craig Williams, my friends and coworkers at AECOM— formerly URS—are archaeologists and founders of CAIRN. They invited me to function as the group geologist, although I assist in many other ways as needed. CAIRN was established in 2008 to fill a void in archaeological and cave studies. CAIRN is typically contacted by private landowners, cave research organizations, and government agencies, such as the U.S. Forest Service. In some cases, people have a cave on their property and want to know if there has been any prehistoric activity there. In other cases, cave research groups look to CAIRN to culturally assess a cave as part of a larger project or in conjunction with federal agencies. When archaeological sites are located, they are documented non-destructively and in-situ with techniques that best fit the situation (photos/sketch maps/video/survey).

Artifacts are not removed. Once we have recorded the site, CAIRN sets about writing a report that is given to the relevant party or parties. Cave locations are kept discrete by CAIRN. Peter Campbell, a fellow archaeologist and colleague, heads up CAIRN’s Submerged Archaeology Division.

As the CAIRN geologist, I help describe the geology of the surrounding cave systems that house these archaeological sites. I offer a wider prospective of cave use and patterns of occupation. In Missouri, there are plenty of cave-forming rock units; such as the Gasconade Dolomite, Pearson Formation, and St. Louis Limestone. A random rock fragment may have been shaped by erosion, instead of man. Chert fragments may have been reworked to make an arrowhead or spear point. In other cases, some rocks that are not present in a particular area or formation were brought in for some purpose—burial slabs, trade, etc. One of my roles is to identify rock types and discern if they are “local.” This isn’t limited to prehistoric sites. A CAIRN project at a historic mine site had several pits with piles of tailings nearby. In some of these pits, I could tell what the marker beds were in the ore veins that the prospectors were chasing, based on the waste quartz fragments left behind in the pits. I also helped identify what may have been considered “waste” rocks as opposed to what may have been shaped by far older geologic or non-geologic processes.

image 5Our work has taken us into large and small naturally formed caverns, human-modified brewery caves under urban areas, caves that require crawls or rappelling, and also shelter caves. Investigations span prehistoric and historic archaeology. Some of our investigations have been more historic in nature. In 2013, CAIRN was asked to help identify car parts from a Model-T that were dumped in a pit cave. Trained CAIRN specialists (including me!) rappelled 70 feet into the cave to document the rusted and decomposing parts. We found serial numbers to help identify the make and model of the car. In brewery caves, we have identified bottles to determine the age of the operation and post-brewery use. One brewery cave was found to have a yet-explored submerged second level, which is unusual and industrious for the 1800s. There is likelihood that these perceived isolated brewery caves are part of a network, long since blocked off by prior owners. At another site in 2014, shelter caves, close to a Civil War archaeological site investigated by CAIRN, were found to have unusual markings that could be prehistoric or masonic in nature. Our group has collaborated with academia interested in testing the 3D imaging capabilities of using structured light scanning underground. This research could help refine the use of equipment to further explore caves in areas that would challenge even the most adventurous caver. It could also help investigate cave collapse or flooded mines.

As an organization, we strive to cause as little damage to the cave and archaeological site as possible. The cave can be a habitat for various species, some of which are endangered. The goal is to leave it as we found it. We also maintain privacy of the cave locations for the people who invite us onto their property, as well as out of respect for the cave and preserving it for future generations.

Why is cave stewardship and cave archaeology important? Looting is a serious threat to caves. Caves are more than just shelters from the elements, as depicted in cartoons and books.

image 3In many cultures, it was the entrance to the underworld. People buried their dead in caves sometimes, with gifts or belongings to help them on their journey though the spirit world. In most cases, this sanctity is damaged or destroyed by present-day looters. Many of the caves that CAIRN visits across Missouri have been looted for their “treasures.” This is more than just exploring for arrowheads and bits of pottery on the ground. It is the systematic excavation of prehistoric graves for anything of monetary value included in these final resting places. This not only damages an archaeological site, it in turn damages the delicate cave environment by rerouting drainages, disturbing the ecology, and destroying formations. It is something to consider during your next visit to the rock shop along the highway or your next Amazon purchase of geologic material. Regular cave visits like those by CAIRN or cavers allow monitoring of the archaeology and biology, so we can keep an eye on threats.

When allowed and applicable, CAIRN reports the findings to the appropriate state historic preservation agency. This archaeological site, and hence the cave that contains it, will then be on the state record. Only archaeologists have access to this record when researching projects. In numerous cases, logging cave and archaeology sites with the state authority has provided information that has helped save both caves and archaeological sites from imminent destruction from a construction project such as a pipeline or road. CAIRN investigations are also helpful and required when other cave advocacy groups attempt to gate caves to keep out looters or vandals.

CAIRN has provided me a way to learn about archaeology and their corresponding interplay with caves and geology.

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