Lamb Spring Archaeological Preserve: Digging Deeper into Roxborough’s Prehistoric Past

Article by: Kathy Weiss 


It’s difficult to imagine that in our modern upscale community a woolly mammoth was killed and butchered here some 13,000 years ago. Evidence that ancient people slaughtered the creature near the end of the Ice Age was revealed on private land just a few hundred yards from the curve on Titan Road.  

On the same rural property just east of what is today Rampart Range Road and steps away from the High Line Canal, paleontologists found evidence of a massive bison kill that took place 8,800 years ago. That was 3,000 years before the first human writings were discovered in ancient Mesopotamia, and before Stonehenge and the Pyramids were built. 

The site is known today as Lamb Spring Archaeological Preserve, named after Charles Lamb, the rancher who owned the land, and you can visit it. Free group tours are held throughout the year; information can be found at Supporters hope to some day create a larger interactive exhibit at the site to teach visitors about the ancient history of this area.

Cameron Randolph, a volunteer board member of the Lamb Spring Archaeological Preserve and a science and technology teacher at Rocky Heights Middle School in Lone Tree, holds an exact replica of a mammoth femur bone found at the site. Photo by Kathy Weiss.

About 25 people attended a tour and presentation facilitated by Stephanie Boktor, an archaeologist at History Colorado, Denver, in early October at Roxborough Library. Boktor said the Lamb Spring site was important to the archaeology community nationally and internationally because it was uniquely situated in a natural spring—now dry—which protected the fossil deposits from degradation for thousands of years. “Because it was a spring,” she explained, “the earth was really preserved. It allowed animal bones and artifacts to be buried quickly. We are really lucky that it was on an active spring.”  (Boktor describes Lamb Spring as both “an archaeological site and paleontological site” meaning human artifacts and animal bones have been recovered there.) 

The first bones were discovered by Lamb in 1960 as he attempted to enlarge the spring on his land to form a stock pond for livestock. 

“He was a rancher and oil guy,” Boktor explained as she related how Lamb, while using a backhoe to dig the stock pond, exposed the tusk and bone fragments of a wooly mammoth and then notified the U.S. Geological Survey in Denver. Dr. G. Edward Lewis, a paleontologist, came to the site and identified the remains of mammoth, bison, horse and camel, along with smaller mammals and rodents. “It was really fortunate that Lamb was curious and brought this to the rest of the world,” Boktor noted, adding that some people might be tempted to keep such discoveries to themselves. 

In 1961, a team from the U.S. Geological Survey, the National Science Foundation and the Smithsonian Institution began excavating the site to map soil levels. During the process they uncovered the remains of Pleistocene-era mammoth bones and bison bone bed, along with artifacts that were carbon dated to have been used 1,000 years ago. This work demonstrated that ancient people hunted animals at the site for thousands of years. The project concluded in 1962 and the trenches they dug were backfilled to protect the fossils.  

Scientists returned to the site in 1980-81 to excavate and examine the bones more closely. 

The following excerpt from the Lamb Spring website gives us a glimpse back in history. “After mammoths and other Ice Age animals had become extinct, people hunted and killed bison at the spring sometime between 8,500 and 9,000 years ago. These people used stone tools associated with what archaeologists call the Cody complex. In 1980 and 1981, Dr. Dennis Stanford (Smithsonian Institution archaeologist) also excavated the site and recognized evidence suggesting that people may have hunted the Ice Age mammoths. He also found evidence of the remains of over 30 mammoths that died near the spring.”

A visitor looks at the casting of a mammoth at the Lamb Spring site during International Archaeology Day. Photo by Thomas Cooper.

Boktor shared that in the lowest level of the excavation, Stanford and team found mammoth bones with signs of flaking, fractures and cut marks indicating human activity. “We think humans were processing the bones,” she said. The team also found “unique, early evidence of human occupation including artifacts and tools with similar shape and characteristics,” which meant they came from a pre-Clovis culture between 11,000 to 13,000 years ago.

According to Boktor, it was during this dig that “they found a large 33-pound river boulder at the site, with one side that was dimpled more than the other.” A stone of that size was out of place amid the rocky soil comprised of very small stones and pebbles, she said, which led the scientists to conclude “that someone went to the Platte River and brought that stone back to process bones” to extract the marrow for food.

Violet Hoffman, 9, and John Warner, 4, of Roxborough crack and crush acorns during International Archaeology Day to learn how ancient people made flour. Photo by Thomas Cooper. 

Dr. Stanford backfilled the site again following the 1981 field season. However, his work exposed an area of some 2,400 square feet and recovered bison bones and artifacts as evidence of the widespread Cody complex—or Paleo-Indian culture—which was present at the site. Those artifacts are now housed at the National Museum of Natural History in Washington, D.C.

Then in July 2002, a team from the Smithsonian, the Denver Museum of Nature and Science, the University of Colorado-Boulder, Douglas County, and the Archaeological Conservancy supervised the excavation of a Columbian mammoth skull which had been discovered earlier and was reburied in 1981 to ensure its preservation. The skull was transported to the Denver Museum of Nature and Science where it was stabilized and cast before being displayed for a year-long exhibit after which it was placed in storage where it remains today.

Colorado Parks and Wildlife volunteer Jim O’Brien throws a spear at Lamb Springs site during International Archaeology Day while Ben Moss, Nathan Barnes, and Max Rikon from Boy scout pack 538 look on. Photo by Thomas Cooper


Stephanie Boktor with History Colorado gives a tour of the Lamb Spring dig site during International Archaeology Day. Photo by Thomas Cooper.


A plaster replica of the mammoth skull is displayed in a small building at the site of the former spring located off of Titan Road. According to Cameron Randolph, a volunteer board member of the Lamb Spring Archaeological Preserve, who also teaches science and technology at Rocky Heights Middle School in Highlands Ranch, there is an ongoing effort to raise funds to create an interpretive center at the site. Boktor describes that effort as a “continuing conversation” about how best to present this part of local history, particularly since tours are free and do not generate revenue.

Addressing her audience at the library before touring the site, Boktor asked, “Why did you come here?” She said the same attributes that bring people to this area today drew animals and prehistoric people here thousands of years ago. “It was very advantageous to live along the Front Range,” she said, describing life in Roxborough back then as a “wet and buggy” environment where mammoth, bison and camels roamed. “There are tons of (archaeology) sites in Ken Caryl, Morrison and along the Front Range,” she added, [because] “where the ecosystem was more diverse, more could survive here” as is still true today. 



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