Comet May Have Exploded Over North America 13,000 Years Ago
A "black mat" of algal growth in Arizona marks a line of extinction at 12,900 years ago; Clovis points and mammoth skeletons were found at the line but not above it.
Credit: Allen West, UCSB
Download the high-resolution JPG version of the image. (2.6 MB)
Use your mouse to right-click (Mac users may need to Ctrl-click) the link above and choose the option that will save the file or target to your computer.