In a 2017 Nature paper, Holen et al. claimed to have found a 130 000 year old archaeological site (CM site) in southern California, where humans had butchered mastodon and left cobble and anvil stone tools. The claim was immediately criticized. The main critique so far has been that the evidence is no more consistent with 130 000 year old human activity than with the action of a number of natural and more recent human processes.

For example, Ferraro et al. (2018) showed that the faunal material at the CM site was not markedly different from material found at other mastodon sites where human activity is not suspected. Despite Holen et al’s claims, it seemed that the spiral fracture patterns found at the CM site could be the result of natural agents. Others questioned whether heavy machinery activity related to the construction of State Highway 54, which led to the discovery of the Cerutti Mastodon, could have generated the broken cobles and fractured bones that Holen et al. claimed as evidence of a 130 000 year old archaeological in Southern California.

So while the CM site could have been the result of ancient human activity, accepting the claim meant multiplying the age of the oldest known archaeological remains in the Americas by a factor of almost 10. Naturally, most archaeologists agreed that simpler explanations for the material were preferable.

Now Ferrell (2019) contributes significantly to the critique by showing for the first time that at least some of the claimed evidence is actually more consistent with recent human activity than with the 130 000 year old butchering of mastodon with stone tools. After a recent visual inspection of the site, and using primary sources, including diagrams of the original Route 54 construction plans, Ferrell not only demonstrates that significant heavy machinery activity affected the site before discovery, but that some of the evidence still visible on the ground, and which is similar to the CM site evidence, is clearly consistent with the effects of modern construction work.

The bones

Ferrell presents clear evidence that the area of the CM find was directly affected by heavy equipment activity during the construction of Route 54 and its accompanying sound berm. It stands to reason that heavy equipment traipsing all over the site, including excavator work, grading, and regular truck traffic could possibly have produced the kinds of fractures reported by Holen et al. as evidence of ancient butchering.

The most important point, however, is that Ferrell shows direct evidence that the CM faunal assemblage, including the mastodon bones, were directly affected by heavy equipment activity. Referring to a photo in the report:

“moreover, on the substrate to the left …  are numerous angular shards of what appears to have been pedogenic carbonate crust such as is seen in situ on the rib fragment above (now to the right of) CM281. Indeed, pedogenic carbonates seem to be otherwise absent from the other bone fragments and the femoral heads in these photographs. This suggests post-depositional disturbance of the site.”

In other words, the carbonate crusts were broken off the bones by heavy machinery before the archaeologists found them.

The lithics

Even more damaging, Ferrell examines some of the CM site material on display at the Natural History Museum in San Diego, and finds that it is more consistent with recent than ancient origin:

“CM423, a pegmatite cobble found in grid square G5, is displayed in a glass case with refits found in concentration 1 at the San Diego Natural History Museum exhibit. These fragments show remarkably fresh-looking fracture faces. The faces sparkle in the lighting, and are un-dulled by any weathering or other alteration. One might expect to see some sign of chemical weathering considering 130,000 years of exposure to fluids, which promoted the heavy pedogenic carbonate crusts seen on some of the bones.”

Ferrell even finds remains, still at the site, which are clearly associated with the construction work, and which are consistent with those reported as archaeological in the report:

“Stones can be seen to the left of the blade of the bulldozer, along the fence between them and the adjoining yard to the east. They were near station 230 + 65 ± and have been recently observed and photographed by the author in the same location (4/10/2018). They are of the same character as the stones described in Holen et al. and exhibited at the San Diego Natural History Museum. They are sub-angular andesitic cobbles and well-rounded granitic cobbles (Figure 3).”

The accompanying photo is quite convincing.


Figure 3, reproduced from Ferrell 2019.


The CM site evidence has been criticized from the start as no more consistent with ancient activity than with later disturbance. Now, Ferrell has clearly shown that at least some of the claimed evidence is more likely to have been produced by recent construction activity than by archaeological presence in southern California 130 000 years ago.


Ferraro JV, KM Binetti, LA Wiest, D Esker, LE Baker, S Forman 2018. Contesting early archaeology in California, Nature 554: 479-483).

Holen et al 2017. A 130,000-year-old archaeological site in southern California, USA, Nature 544:479-483.

3 thoughts on “The Cerutti Mastodon claim is further weakened by Ferrell’s analysis

  1. First off it is not a butchering site but a bone processing site. Big difference. Secondly and most important the material was cemented by unbroken pedogenic carbonate crusts preserved in undisturbed well consolidated Pleistocene sandstones and siltstones contrary to Ferrell’s extremely inaccurate article written 25 years after the fact . There was an exception to this, being a few elements at the extreme North East edge of the site footprint that were raked by the excavator bucket where the 2 tusks were located. Speaking of the tusks, one vertical and the other horizontal, I excavated both. These specimens were hit by by the bucket teeth creating thousands of tiny white fragments which led to the site’s discovery. The major percentage of both tusks that were remaining were solidly cemented in undisturbed Pleistocene sandstone and siltstone. The undamaged distal portion of the vertically oriented tusk extended to over 70 centimeters into the D Bed fine grained sandstone. This vertically oriented tusk was preserved in a D Bed sandstone concretion absolutely undisturbed by modern human activity. We have been monitoring construction sites such as Rt. 54 since 1981 and are very familiar with what heavy machinery does to bone. The vertically oriented tusk was not jammed into the D Bed by the excavator as the force required to do so would have completely destroyed the fragile tusk. The vast majority of the CM Site was completely unaffected by heavy machinery, protected by undisturbed formation with again the exception being the extreme N E edge. The north 2:1 cut slope of the sound berm was defoliated and cut prior to the main freeway right of way by the excavator. The 5 ton dump trucks would have plenty of room on the yet to be graded right of way immediately south of the sound berm to operate. No trucks operated on the north side of the sound berm down where the CM Site is located as there is no room for them to operate there between the homes and the sound berm. Ferrell’s forensics again 25 years after the fact, contradicts our extensive field notes, videos, dozens of still pictures taken during the over 5 months of grading. Tom Demere would have graciously given access to this material. The rocks of Figure 3 are home owner deposited as is the gravel. Good lord, you people are desparate! Whether the CM Site is archaeological or strictly paleontological is irrelevant in this case. Ferrell should have done his homework.


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