Pre-Clovis Site in Texas
DUNCAN - Well, there's been a discovery in Central Texas that's stirring-up the debate on the first peopling of the Americas. Thousands of stone artefacts have been unearthed in a creek valley northwest of Austin, including more than 50 tools which potentially pre-date the technology used by the Clovis people. The contents of this site could finally put an end to the 'Clovis first' model.
DIANA - What do you mean by 'Clovis first' model?
DUNCAN - It has long been argued that the first people in the Americas arrived from Asia via the Bering Strait during the last Ice Age, sometime around 13,000 years ago. These hunter-gatherers produced a very distinctive stone tool technology, including characteristic fluted projectile points that were first discovered at a site near the town of Clovis in New Mexico in 1929, hence the name: 'Clovis culture'. Whether or not this distinctive style of technology came with them from Asia, we don't know, but it quickly spread throughout much of North America by the end of Pleistocene, around 12,000 years ago.
DIANA - So this recently-discovered site in Texas pre-dates the Clovis culture? What did they actually find?
DUNCAN - The team of archaeologists and other scientists, led by Dr. Michael Waters, director of the Centre for the Study of the First Americans at Texas A&M University, recently published their findings in Science. The site at Buttermilk Creek consists of a large assemblage of projectile points, blades, chisels, choppers and an abundance of flakes made out of locally-sourced chert, which were found in a layer of thick clay sediments immediately below a layer of Clovis material. These newly-discovered tools are sufficiently different from typical Clovis material to be a distinctive technology in their own right.
DIANA - But how were they able to date the site? Apart from the obvious stratigraphy you mentioned, was it just by looking at the differences in stone tool technology or were they using other methods?
DUNCAN - Good point and, yes, stratigraphy in floodplain deposits like this one can be unreliable. In fact, anthropology professor Tom Dillehay from Vanderbilt University and Professor Gary Haynes from the University of Nevada both suggested that the artefacts could have migrated through the layers of clay to create the potentially false impression of a pre-Clovis layer. So, Dr Water's team used a technique called optically stimulated luminescence (OSL), to assign a date to the tools of 15,500 years ago.
DIANA - Going back to my Undergraduate days, I seem to remember there were quite a few contentious sites in the Americas that pre-dated the arrival of the Clovis people. What's so special about this site?
DUNCAN - You're right, this isn't exactly new. In recent decades, archaeologists have been finding more and more evidence for pre-Clovis people in the Americas, and specialists have been questioning the routes these early migrants took across the continent or ocean. What is interesting is the idea that these earlier tools may be ancestral to the Clovis material, since they appeared 2500 years earlier. And they could settle the debate on whether or not the distinctive Clovis technology was an Asian import or actually developed in the Americas.