This round, two-mile wide valley in Houston and Stewart counties is eroded in rock that once was under a meteor crater. The fertile basin, composed of soil weathered from deeply buried limestone thrust to the surface by the meteor’s impact, has attracted people ever since Paleoindians camped there about 10,000 years ago. The center rock, which is raised 2,500 feet, and soil are like the ridge at Knoxville; nearby farmland is like that near Murfreesboro and Columbia. The valley results from dissolving uplifted limestone surrounded by–since flint resists erosion–forested hills of flinty rock. Two fault rings surround the valley: the outer one is four miles from the center and touches the town of Erin.
A meteor or comet struck with the force of an atomic explosion 95-320 million years ago. It blasted out a crater and momentarily squashed rock down and out. Seconds later, rocks rebounded up and in. The present basin has rock that jumped highest, but could not fall all the way back, because the space was filled by rock springing in from the sides. Conical fractures called “shatter cones” occur in the rock that was under the impact. The two fault rings were open cracks after the impact. They filled with rock that fell in. The crater eroded away long ago, along with at least 500 feet of rock.
Although the size of the meteor (or comet) that formed Wells Creek Basin is not known precisely, a 20-million-ton meteor or comet striking at 25 miles per second (90,000 mph) could blast a four-mile crater and make the uplift and ring faults. A stony meteor that heavy would be 900 feet in diameter.