Lubbock Lake (image) University of Chicago Press Journals Caption This image shows the excavations at the Lubbock Lake site, on the High Plains of Texas. The crew is working in the laminated lake beds dated 13,000 to 12,000 years old. The time of the purported extraterrestrial impact would be at the base of the lake beds. The pale olive yellow layer below contains Clovis-age bone. The black layers represent a marshy valley bottom and contain archaeological bone beds (with butchered remains of extinct bison). The white layers are archaeologically "sterile" because they represent standing lake water (probably 1 to 2 m deep). Thus, the presence of "sterile" zones between occupation layers has no bearing on the issue of an impact and people. Credit Vance Holliday Usage Restrictions None Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.