What lies beneath

Douglas County's buried artifacts tell stories of mysterious times

Posted 4/11/16

Five years ago, when Douglas County was in the process of building RidgeGate Boulevard, a construction crew stumbled upon a curious sight: the charred remains of a palm tree.

The find motivated county project manager Sean Owens to look further …

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What lies beneath

Douglas County's buried artifacts tell stories of mysterious times


Five years ago, when Douglas County was in the process of building RidgeGate Boulevard, a construction crew stumbled upon a curious sight: the charred remains of a palm tree.

The find motivated county project manager Sean Owens to look further into how the tree ended up roughly 20 feet below the ground surface. He discovered what a surprising few in the Denver area have come to learn, and that is the fact that an ocean and, later, a rainforest once covered the Front Range.

A set of stone pillars at Native Legend Park in Castle Rock describes the decimation of the rainforest and notes that “37 million years ago, this would have been a very bad place to be standing.”

A volcanic eruption somewhere in the area of the Collegiate Peaks (Mount Princeton, Mount Harvard, Mount Oxford, etc.) in Colorado's Sawatch Range sent a “fiery avalanche of airborne molten rock” toward the Front Range and “animals were literally entombed in the superheated volcanic ash right where they stood,” according to the Denver Museum of Nature & Science, which provided information for the pillars at Native Legend Park. The solidified ash and the organic material it buried created a 20-foot-thick layer of rhyolite.

Owens and the construction crew had found a 24-inch-diameter tree trunk that was “half petrified and half burned” and sticking out of the bedrock. Carbon dating put its age at between 30 million and 50 million years old.

“It was just the weirdest thing to see,” Owens said. “That whole area — the Hess, Ridgegate and Lincoln area — they'll find those burned trees from that volcano.”

It's just one of the fascinating stories that explore the evidence of landscapes and civilizations from the past, and what lies beneath the feet of Douglas County's current inhabitants.

Something old, something new

Not every find, of course, is tens of millions of years old. Artifacts uncovered at the Rueter-Hess Reservoir site within the last 10 years provide insight into separate civilizations of paleo-Indians and hunter-gatherers who lived in the area between 2,000 and 5,000 years ago. Evidence of pit dwellings — and even an artifact depicting what many believe to be a dog — were painstakingly unearthed by URS Corp. and a team from Centennial Archaeology.

Perhaps the most significant archaeological site in Douglas County was found completely by accident in the late 1960s.

“A rancher was cleaning up his stock pond with his backhoe and he found a piece of a mammoth,” said Judy Hammer, a planner with the county's community development department. “He knew it was a big bone he had never seen before.”

The rancher called a museum in Denver, which called experts from the Smithsonian in Washington, D.C., to take a look. It was the skull of a young mammoth. Between the 1970s and the early 1990s, archaeology teams excavated what's now known as Lamb Spring, a watering hole that attracted creatures of all types thousands of years ago. Some became mired in the mud and never got out, and their skeletons were well-preserved.

“They found a lot of animals that were alive during the Ice Age: the sloth, the saber-toothed cat, camels,” Hammer said.

Norma Miller, an archaeologist and curator of the Douglas County History Repository, said the area was used over time by different tribes of people, and tools were found that spanned thousands of years “all the way up to contact with Europeans, which was the 1840s,” she said.

The site — off Titan Road west of Highway 85 — is now governed by the Lamb Spring Archaeological Preserve, a group led by a volunteer board of directors made up of some of those who excavated the area. The group leads free guided tours of the site from May to October. Find more information at www.lambspring.org.

The search for Blackfoot Cave

Blackfoot Cave, a few clicks south and east of Castlewood Canyon State Park in Douglas County, is actually not a cave, but rather a rock shelter that was “occupied off and on for centuries,” said Miller, who added that more than 5,000 bags of artifacts were recovered from Blackfoot Cave during an eight-year excavation that ended in 2014.

“We've got stuff from 7,000 years ago,” she said.

The site has produced hundreds of spear points from different eras. Charcoal from a roasting pit was particularly helpful in determining how old some of the artifacts are. Blackfoot Cave is a natural stone feature made partly of a rock outcrop along East Cherry Creek. Because it faces southwest, it was an ideal place to live, providing shelter from incoming winter storms and taking in a nice breeze during the summer, Miller says. It also has a great view of Pikes Peak and is in close proximity to water and a wooded area.

Blackfoot Cave is now owned by Douglas County, but it almost went undiscovered and forgotten by time. A settler who explored the area around 1842 kept a diary of his travels and detailed a trip he took with a group that included Blackfoot Indians. When they encountered a brutal storm, they sheltered in Blackfoot Cave, Miller said. The diary kept interest alive in small circles for decades and piqued the curiosity of historians. However, private property owners would not grant access to the area where Blackfoot Cave was believed to be. It wasn't until one property owner gave the OK that the site was rediscovered, and the county later purchased the land.

It was a surprise to Miller that the site was so intact when an archaeology team finally got the chance to recover cultural relics.

“Settlers lived there and a lot of that stuff wasn't destroyed. And there it sat for thousands of years,” she said.

Committed to preservation

Archeological surveys have been around since before the county's growth spurt in the 1990s and early 2000s. A large-scale one was conducted in the late 1970s before construction began on Highlands Ranch.

It was during that time that historic preservation became more of a priority in Douglas County. Regulations came in handy in 2002 when a crew working on the north side of Stonegate dug up a mammoth skeleton that turned out to be as much as 200,000 years old. The tusks are on display at Parker Town Hall.

When a development is proposed, the county has what's known as a “referral period” in which agencies that would be affected by the project are able to provide feedback to elected officials who approve or deny applications for development. The Douglas County Historic Preservation Board is among those agencies, and it searches a state database of historically significant sites in the area and looks at aerial photographs. The intensity of the archaeological survey often depends on the likelihood of finding cultural resources, and sometimes Miller is given access to provide a cursory glance at the surface.

“You'd be surprised how much you can see if you know what you're looking for,” Miller says.

After research and a survey, Miller makes recommendations to the developer or property owner, and these days, developers are more receptive to the idea of preservation, she said. But it's difficult to know how many artifacts have already been buried by residential and commercial development.

“Untold,” Miller says.

Nudging from the county and cooperation from developers has resulted in the discovery of “little pieces of the puzzle,” as the archaeologist and longtime Douglas County resident puts it. If done correctly, the discovery of artifacts does not have to cause significant construction delays. A perfect example is the Parker Water and Sanitation District's willingness to work with archaeologists when cultural finds, including the pit dwellings, were uncovered at Rueter-Hess Reservoir, said Miller, who put together a display case of artifacts that is now in the lobby of the water district's purification plant near the reservoir.

“What we say is just 'please let us get in there to see what's there and get it taken care of and then we'll leave you alone,'” Miller said.

More than a million dollars was spent on excavating when Rueter-Hess Reservoir was being built, “but, boy, it was really worth it because it's added a tremendous amount of knowledge on how the land was used,” she said.

Artifacts from Lamb Spring are at the Denver Museum of Nature & Science and the Smithsonian, but the vast majority of the 14,000 cultural resources found locally are at the history repository, where Miller carefully catalogs them and places them in boxes. The items are featured on Douglas County's Virtual History Museum, a website that contains a series of stories and photographs of the artifacts. Now, all that's needed is a brick-and-mortar space to further drive public interest in history.

“The county really needs a countywide museum,” Miller said.

With thousands of acres still to be developed in Douglas County, there will likely be much more to talk about. If petrified palm tree trunks and the remnants of long-extinct goliaths are known to be below the surface, it begs the question: What else is down there?

“I've never found dinosaur bones during a project," Owens said, "but you never know."


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