Nature Notes: Blood, Sweat, and Archeological Discovery in Eagle Cave

Pictured above, attendees of a Texas Archeological Society academy visited an excavation in Eagle Cave, a massive rock shelter near Langtry, Texas. Deposits in the cave preserve a 13,000-year record of prehistory, and the transition between light and dark soils at the site signals a pivotal transformation in Native American life.

Near Langtry, Texas, in January 2017, the Texas Archeological Society hosted the Lower Pecos Canyonlands Academy. It was an immersion in new research into Texas prehistory.

One focus of that research is Eagle Cave. The cave, deep in a canyon near the Rio Grande, attracted human communities for 13,000 years. Sediments accumulated through human use, and those sediments preserve tools and bones, traces of plant foods, ancient latrines.

What does this site have to tell us? And what does research here entail?

“In 1935, 36, the Witte Museum did the first large-scale excavation at Eagle Cave,” archeologist Charles Koenig said, “and they dug what became this trench…”

The limestone walls of Eagle Nest Canyon shine in afternoon light. But academy members stand in shadow, atop the ashen soil of Eagle Cave. A trench – 15 feet deep, 40 feet wide – cuts into that soil.

There were excavations here in the 30s and the 60s. But in 2014, researchers with Texas State University returned, to re-open the collapsed trench. It’s part of the Ancient Southwest Texas Project – a new look at archeology here.

Dr. Charles Frederick is in the project.

“This is the first time one of these shelters has been available to actually see,” Frederick said. “These are the best archeological record we have. So when I had the opportunity to see it, I was like – yeah, I’m there. It is not going to be on view again probably until our grandkids are our age. ”

One feature of the trench leaps out. For the first 10 feet, cave soils are gray. Then there’s an abrupt line – and the deepest layers are yellow.

That line represents a transformation in the lives of ancient West Texans, Frederick said. As the great Ice-Age game – mammoths, sloths, ancient bison – vanished, and human populations increased, Native peoples made a life-giving discovery. By cooking the hearts of lechuguilla and sotol in earth ovens, they could turn the otherwise inedible desert plants into food. It was a “carbohydrate revolution.”

“This is the clearest example I’ve even seen in my career of that transition,” Frederick said. “Paleoindian hearths are flat things on ground surfaces. They don’t make burned rock intentionally, because they’re not cooking with it. Here, it’s binary. It’s yellow on the bottom, and brown and black on top. I’ve seen it nowhere else where it’s as clear as this. That is a technological revolution.”

Gray soils are the result of earth-oven baking, and can yield new insights into the practice. Earlier archeologists thought the deeper soils were devoid of cultural artifacts. But these researchers unearthed butchered remains of mammoth and antiquus bison. Here, Ice-Age hunters cooked their kills, and likely mined the bones for tools.

The researchers made another rare find: an archaic latrine, with scores of coprolites, or fossilized human feces. With analysis, the coprolites will disclose the diets of ancient peoples.

Then, there are bugs. Winged insects are an excellent gauge of climate – if they don’t like the conditions, they fly away. Beetles, preserved intact in Eagle Cave’s dry soils, could help generate a detailed account of environmental change.

Archeology may be an intellectual pursuit. But it also calls for a strong back. And digging is the easy part.

The original archeologists at Eagle Cave left their trench open. It slumped and collapsed. Deposits of different ages mixed, limiting what could be learned.

In February 2017, the Ancient Southwest Texas crew set out to backfill their trench. There were engineering challenges – and lots of hard work.

The archeologists built a chute, to convey sand from the canyon rim to an enclosure outside the cave. Teams moved the sand in carts – 400 pounds each – and dumped it in the trench. Over weeks, they moved more than 270 tons of sand.

Charles Koenig led the excavation.

“That’s where the challenge comes in – we have to import all the fill that was lost from 1932, till some time in the 1980s or 1990s, when the slopes reached their angle of repose,” Koenig said. “We have to bring all that fill back in, in addition to backfill everything that we removed, to preserve and protect the site.”

Eagle Cave is a unique cultural resource. Excavation is done for now. But in the years to come, the evidence recovered here will shed new light on natural and human history.

Nature Notes is underwritten by the Dixon Water Foundation and is produced by Marfa Public Radio in cooperation with the Sibley Nature Center. This episode was written by Andrew Stuart.


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