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The Lamb Spring Site

The Lamb Spring Site was initially established as a result of geologic mapping fieldwork for the Kassler Quadrangle by Glenn Scott in 1953. Fossils were collected for the purpose of dating surficial deposits. The assemblage included: rodents, camels, and elephant teeth and bone fragments. The assemblage also included several Native American artifacts.

detail of quadrangle showing the location of the Lamb Spring Site south of Denver, Colorado
photo of the Lamb Spring site with original notes

Figure 1. Location of the Lamb Spring Site, south of Denver, Colorado. The site was initially established as USGS-Denver vertebrate paleontology locality D-42 in 1953.

Figure 2. Original site photo taken by Glenn Scott in 1953 with features outlined. Click on image for a larger view.


In 1958 the rancher, Charles Lamb, uncovered numerous bones working with a backhoe while excavating the spring as an additional water-source for his cattle. He promptly contacted his neighbor Eddie McKee (USGS-Oil and Gas Branch). Eddie contacted Frank Whitmore (USGS-Washington Paleontology & Stratigraphy Branch), who in turn contacted USGS-Denver vertebrate paleontologist G. Edward Lewis. Lewis, his tech Bob O'Donnell, and Glenn Scott visited the rancher's excavation. Ed and Bob drilled more than 100 auger holes hunting traces of bone to plot the dimensions and make preliminary site map (fig. 3). (Samples were also prepared for pollen analysis by USGS-Denver palynologist Estella Leopold.) Trenches dug to document soil horizons uncovered not only additional bones (some with carving or trampling marks) but also an assemblage of Paleo-Indian projectile points. The bones indicated late Pleistocene age. Activities by very early man in North America always pique scientific curiosity. The complex was recognized to be an important local archeological site. Lewis realized the uniqueness of the spring deposit as well as the enormity of the potential excavation site. The Denver Paleontology & Stratigraphy Branch did not have the available manpower to take on a large archeology project (fig. 4). Lewis referred the job to Waldo Wedel (United States National Museum-archeologist).

two site maps for the Lamb Spring site
Figure 3 and Figure 4. Site maps of the Lamb Spring Site. See a larger view.


Wedel conducted Smithsonian site excavations with USGS support during the summers of 1961 and 1962 (see preliminary site map sketches, the lithology cross-section [fig. 5], and photographs [figs. 7, 8]). Throughout excavations Ed, Glenn, and Bob provided machinery, tools, and geological insight for the project. Paleo-Indian artifacts attributed to the Cody complex indicated very early ages for human activity in the area. Bones from the lowest stratigraphic layer were submitted for radiocarbon dating. The analysis provided a very old date of 13,200 years before present, considerably older than other regional human settlement. Waldo Wedel and Glenn Scott proposed that the site indicated a likely hunting/butchering site by Paleo-Indians. Ed Lewis deferred, evidence more likely indicated animal trampling and reworking throughout the Pleistocene and Recent ages. lithology diagram for Lamb Spring site

Figure 5. Lithology cross-section of the Lamb Spring Site as composed by Waldo Wedel and Glenn Scott.


Bones from the site were heavily stained by the black mucky spring mud, obscuring proper identifications. So much so, that in order to estimate the age and genus/species of the mammoth it was necessary to saw a vertical cross-section length-wise through a molar to count the dentary plates (fig. 6). The cut marks on the broken limb bones required careful analysis too. Were the cuts a result of human butchering or from trampling by the numerous large animals terminally stuck in the quagmire? Coincidentally the Ringling Brothers Circus had the misfortune of having one of their elephants die while in Denver. Lewis heard about it and inquired if they would be willing to donate the carcass for a scientific study on butchering cut marks. The carcass was secured in a warehouse down by the railroad yard. Butchering was done with a variety of "Ice Age" and modern tools. Close microscopic examinations were made of the resultant traces. The question of human butchering or animal trampling remained unresolved and remains unresolved to this day in spite of further detailed analyses in a subsequent United States National Museum excavation and lab-work by Kay Behrensmeyer during the 1980's. Without a doubt as new techniques are developed researchers will revisit the problem and re-analyze the bones.

Presently the site is under the watchful eye of the Colorado Archeology Conservancy.

cross section of a mammoth tooth found at the Lamb Spring Site, Colorado

Figure 6. Vertical cross-section cut through mammoth tooth, from Lamb Spring site, Colorado.

Click here to see Figures 7 and 8.