Buttermilk Creek Complex

Buttermilk Creek Complex refers to the remains of a paleolithic settlement along the shores of Buttermilk Creek in present-day Salado, Texas dated to approximately 15,500 years old. If confirmed, the site represents evidence of human settlement in the Americas that pre-dates the Clovis culture.
The Buttermilk Creek Complex found at the Debra L. Friedkin Paleo-Indian archaeological site in Bell County, Texas has provided archaeological evidence of a human presence in the Americas that pre-dates the Clovis peoples, who until recently were thought to be the first humans to explore and settle North America. The site's pre-Clovis occupation is supported by numerous lines of evidence including optically stimulated luminescence dates ranging from 13,200-15,500 before present, undisturbed stratigraphy, and an extensive stone tool assemblage. OSL is a technique that analyzes light energy trapped in sediment particles to identify the last time the soil was exposed to sunlight.

Wikipedia