wells creek impact crater

Shatter Cone from Wells Creek Impact Crater

Sometime between 100 and 300 million years ago, a violent event occurred in what is now Wells Creek Basin in Stewart and Houston Counties of Central Tennessee. A bright light appeared and streaked southward across the sky. A meteorite, traveling 10 to 25 miles per second (36,000 to 90,000 mph), struck the earth with a shuddering impact, accompanied by a supersonic air blast, and penetrated to a depth of 2,000 feet before the tremendous downward force together with the earth’s forces of resistance resulted in a gigantic explosion. The earth shook and earthquake waves raced in all directions. A mighty fiery mushroom of masses of rock and clouds of pulverized rock dust rose high into the air, and fell back to earth. The rock fragments landed quickly, but some of the dust stayed in the air. A great crater was formed, about four miles in diameter and half a mile deep, rimmed by a surrounding pile of shattered rock debris. The crater was mostly filled in by the central uplift. The deafening noise died away and all returned to the peace and quiet that prevailed before the catastrophe.

The earth’s surface appeared to be damaged forever, but millions of years passed and erosion and vegetation softened the ugly scar. The rim of scattered rock disappeared, and the level of the region was lowered many hundreds of feet by the work of rain and running water, mass wasting, gullying, and downward and lateral cutting by streams. Because of the shattered character of the rock in the impact area, the circular scar was eroded faster and therefore deeper than the surrounding region. Thus, circular Wells Creek Basin, as it is today, was born.

Perhaps 10,000 years ago, man first saw Wells Creek Basin, Indian tribes found haven in this pleasant basin that had so much to offer. Game was plentiful, and the streams yielded a variety of fish and mussels. Springs and clear streams were present. The low hill in the middle of the basin afforded an excellent place to camp and to live safely above the highest flood water. Outposts of watchers could guard the trail that entered the basin from the south along Wells Creek as well as paths that crossed the protective rim of hills surrounding the basin. The low central hill could be defended easily. Dense flint found in great abundance in the hills about five miles to the west could be patiently worked into arrow and spear points for war and hunting, large ceremonial flint objects, and many other useful items.

When the first white settlers came from North Carolina and Virginia, they were impressed by the relatively flat, well-drained basin. The soil was better than that of the surrounding hill country. Not only was the soil fertile and essentially free of chert blocks, but it also presented within a small area a variety of soil types formed by the weathering of many types of rock exposed there. Here in the basin, a highly agricultural society developed. The owners, their neighbors and visitors, knew that the soil was different and that the rocks were unlike others in the region. Undoubtedly many wondered why.

The center of the Wells Creek crater contains some of the finest shatter cones in the world. A shatter cone is a conical fragment of rock that is formed from the high pressure of a meteorite impact and has striations radiating from the apex of the cone. The Wells Creek shatter cones were actually formed by the shock waves that arrived before the limestone beds were tilted by the meteorite. The cones formed pointing toward the place from which the shock waves came. The Wells Creek shatter cones were formed by shock waves coming from a position which was (at the time of impact) more than 2,000 feet underground.

On Saturday, February 25, 2006 about 20 members of the Memphis Archaeological and Geological Society were given a grand tour of the Wells Creek Crater by Tennessee state geologist, Marvin Berwind. Mr. Berwind gave us an overview of the formations and fault patterns that make up the Wells Creek structure. We were given an opportunity to view the structure from several locations along the rim before venturing into the crater for an afternoon of exploration and shatter cone collecting at ground zero. Shatter cones were very abundant, although most required a little bit of work to extract from the limestone formations. The Wells Creek shatter cones averaged from about a quarter of an inch to two or two and a half inches in diameter, although shatter cones outside that range were also available.

REFERENCES:
[01] Charles W. Wilson, Jr. and Richard G. Stearns. Circumferential Faulting Around Wells Creek Basin, Houston and Stewart Counties, Tennessee. Journal of the Tennessee Academy of Science. Vanderbilt University, Nashville, Tennessee. 1966.

[02] Charles W. Wilson, Jr. and Richard G. Stearns. Bulletin 68: Geology of the Wells Creek Structure, Tennessee. State of Tennessee. Department of Environment and Conservation. Division of Geology. Nashville, Tennessee. 1968. Reprinted 1993.

[03] Wells Creek Crater. Wikipedia. Answer.com. http://www.answers.com/topic/wells-creek-crater. 27 February 06.