Monte Verde, in southern Chile, has been one of the anchoring sites for the theory that humans reached South America more than fourteen thousand years ago — well before the Clovis horizon in North America. The radiocarbon dates seemed clear: organic materials from the site returned ages of 14,500 years. The site was excavated in the 1970s through 1990s and has been cited in thousands of papers as evidence for coastal migration routes predating the ice-free corridor.
Surovell and colleagues returned to the site and found a problem with the stratigraphy. The deposits along the creek bank are full of Ice Age wood — ancient organic material eroded from upstream deposits and redeposited in younger sediments. The old wood produces old radiocarbon dates regardless of when the archaeological layer formed. The site isn't fourteen thousand years old. It's four thousand to eight thousand years old, with older material mixed in.
The claim is that the layers are scrambled. Organic matter from the Pleistocene ended up in Holocene-age deposits through normal fluvial processes — the creek moving sediment downstream and incorporating ancient wood into younger banks. This is a known problem in alluvial archaeology, but it went undetected at Monte Verde because the old dates were what people expected from a site that was supposed to be old.
The controversy is immediate and fierce. Tom Dillehay, who led the original excavations over decades, contests the reinterpretation. The original team's stratigraphic work was extensive and well-documented. Whether redeposited wood explains the old dates or whether the new team misidentified the sedimentary context is unresolved.
If Surovell is right, one of the foundational pillars of pre-Clovis colonization of the Americas dissolves. If Dillehay is right, the reanalysis is flawed geology applied to a well-characterized site. The evidence hasn't changed. The interpretation of how the evidence got there has.