Some 60 km southeast of Socorro, N.M., a low gravel ridge runs above the Chupadera Wash in the Rio Grande Rift Valley. The remote Mockingbird Gap is a dry, narrow strip half a mile long, but thousands of years ago it was a lush wetland – and a popular site for an early Clovis culture, judging by the wealth of projectile points found there.

Recently, anthropologist Marcus Hamilton, a postdoctoral fellow at SFI and the University of New Mexico, and colleagues examined 296 projectile points from two locations: Mockingbird Gap and a region in the central Rio Grande Rift collected by the late geologist Robert Weber over 60 years ago, the earliest and biggest collection of Clovis tools yet found.

The broad, bifacial spear points fit the manufacturing pattern the Clovis used 13,000 years ago. Geological analyses link all the points’ obsidian, chert, and other high quality stone to a handful of rock outcrops, mostly nearby but some hundreds of kilometers away....