Bureau of Reclamation of Late Pleistocene Archaeology and Paleontology Project

Every year, there is new shoreline erosion at Bureau of Reclamation reservoirs in the Great Plains. Often, this erosion exposes artifacts and fossils from the latest Pleistocene (40,000 to 13,000 years ago). These sites require "salvage excavations" during which Dr. Steven Holen, curator at the Denver Museum of Nature & Science, leads a team of archeologists to recover archaeological and paleontological materials.

"It's a cooperative agreement between DMNS and the Bureau of Reclamation," Dr. Holen said, "We help them fulfill their obligations-under several laws-to salvage these important scientific materials." In return, the Museum has the opportunity to evaluate and publish these salvaged materials, which sometimes prove to be significant finds.

"We keep finding evidence that humans were in North America much earlier than previously thought," Dr. Holen said. One excavation revealed a mammoth bone that was broken by humans 20,000 years ago.

How are these objects found? According to Dr. Holen, the concept is pretty simple. Walking surveys of eroded shorelines identify sites where excavations are needed. Then, they dig.

Usually, one excavation is conducted each year. Most of these excavations take only a few days, but the team often returns to sites years later as new materials are exposed. In 2002, the team conducted excavation of mammoth sites at Lovewell Reservoir in Kansas and Medicine Creek Reservoir (called the Hamburger Mammoth Site) in Nebraska. Both of these sites were revisited as erosion exposed more of the mammoth skeletons.

After excavations are complete, salvaged archaeological and paleontological materials temporarily enter Museum collections. Dr. Holen's team analyzes and stabilizes the bones before they are returned to the Bureau of Reclamation.  Several important publications have resulted from this co-operative venture. 

Early Humans in the Americas Project

When did humans first arrive in the Americas? This has been one of the most controversial questions in American archaeology for more than a century.

"It's important in understanding human adaptability and mobility throughout the world," Dr. Steven Holen said, "And it's our species.  Many people are interested because it's our species."

The Denver Museum of Nature & Science made its first major contribution to the debate in 1927 with discoveries in Folsom, New Mexico. Artifacts and fossils from the Folsom Site proved that humans were in the Americas more than 12,000 years ago-thousands of years earlier than scientists previously thought. In 1933, discoveries at the Dent Site in Colorado proved that humans were in the Americas 13,000 years ago. Dr. Holen continues Museum research on the subject through the Early Humans in the Americas Project.

As Dr. Holen describes it, the project is "two-pronged." The first component involves field research throughout the central Great Plains. Dr. Holen and his team conduct pedestrian surveys of possible dig locations, followed by excavations of late Pleistocene sites on private, state and federal land.

"We're continually surprised at the age of some of these sites," Dr. Holen said, referring to sites that suggest humans entered this area between 20,000 and 40,000 years ago. "We keep finding older and older sites."

The second part of the project involves the evaluation of museum collections across North America. According to Dr. Holen, his team looks for evidence that was excavated previously, but overlooked by the original excavator. From Canada to Mexico, museums have been very receptive of the team's research.

"They're good scientists, and they want to know what's in their collections," Dr. Holen said, "It helps them as much as it helps us."

Working with his wife, Kathe Holen-Anthropology Department Associate at the Museum-Dr. Holen has used experimental methods to show that mammoth bones from the latest Pleistocene (40,000 to 13,000 years ago) were modified by humans. "We were able to replicate fracture patterns found on mammoth bone by using a stone hammer to break and flake elephant bones," Dr. Holen said, "The fact that we can eliminate natural causes for the observed breakage of mammoth bone strengthens the argument that only humans were capable of breaking bones in these patterns."

The Snowmastodon Project™

On October 14, 2010, bulldozer operator Jesse Steele was excavating a reservoir near Snowmass Village when he saw bones coming over the top of his bulldozer blade. Within two days, scientists from the Denver Museum of Nature & Science were on site, and within two weeks a Museum team was excavating what has become one of the most significant scientific discoveries in Colorado history.

The find is an exceptionally preserved Ice Age ecosystem. As of December 2010, the site had produced the remains of eight to 10 American mastodons, four Columbian mammoths, a Jefferson's ground sloth, four gigantic bison, two Ice Age deer, snails, iridescent insects, and plant matter that is still green after more than 45,000 years.

News of the once-in-a-lifetime discovery spread like wildfire throughout Colorado, generating enormous public interest. In the Roaring Fork Valley, 8,500 school children lined up to see the bones and learn about the discovery from Museum educators. During two days in November, more than 3,500 people in Snowmass Village and 2,500 people in Denver attended Mammoth and Mastodon Madness Days to see the fossils and learn more about the Ice Age in Colorado.

For the next six months, the Museum is focusing on preserving the bones from this Ice Age treasure trove and planning next steps. Museum scientists have assembled a team of more than two dozen scientific experts who will gather in Snowmass Village in May 2011 to continue this amazing excavation.

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