A Probable Extra-Terrestrial Impact Crater in Georgia

The Cove Dome, located in west central Georgia, is a round crater.  It’s also known as the Woodbury Impact Structure because scientists who are studying this odd geological anomaly strongly suspect it is the result of an extra-terrestrial impact.  It is 4.2 miles in diameter and has an elevated quartzite rim, but the rock on the floor of the crater is made of schist and gneiss instead.

Merriweather County, site of a probable impact crater.  The Cove Dome is located 3.6 miles southeast of Woodbury, Georgia.

Satellite photo of the Cove Dome, plus 2 smaller craters to the northwest that are probably the result of the same impact event.  The Cove Dome really shows perfectly round on topographical maps.  The rim causes so much radio interference that special satellite dishes had to be built inside the crater for cell phones to work..

The sand found in the Cove Dome has similar shock-induced deformations found in other known impact sites.  The impact may have melted rocks that when cooled became the crystalized, round, charnocktite boulders visible in the crater today.  The unusual psuedotachlytic breccia present here is also evidence of extra-terrestrial impact.  Psuedotachlytic breccia is a glassy fine grained rock often associated with impact structures, however, it’s also found in areas that have suffered earthquake-induced landslides.  Scientists haven’t completely ruled out other origins for the Cove Dome crater, but studies are leaning toward impact.  Scientists have confirmed an extra-terrestrial impact origin for the Wetumpka Impact Crater in south central Alabama.  They found high levels of iridium, an element associated with meteors and comets, and there is also a great deal of shocked quartzite impactites within the crater.  The Wetumpka Impact occurred about 80 million years BP when this part of Alabama was a shallow sea.  The impact devastated an estimated 830-3840 square miles.  The Woodbury Impact is thought to have occurred during the late Cretaceous as well but slightly above sea level.  Neither impact was as devastating as the K-T impact which cooked the atmosphere 65.5 million years ago and wiped out the dinosaurs.  The K-T impact blew rock and breccia into the atmosphere, and scientists suspect some of it landed on Cretaceous deposits located near Columbus, Georgia because this material doesn’t resemble any of the local rock. The K-T impact crater is off the coast of the Yucatan penninsula in Mexico.  Presence of rock blown from Mexico to west Georgia demonstrates what a cataclysmic impact it was.

Illustration of the Wetumpka Impact Crater.

Another major extra-terrestrial impact occurred in the Chesapeake Bay about 35 million years ago.  This impact melted part of earth’s crust and also blew this melted rock into the atmosphere.  Many of these melted shards, known as tektites, cooled and fell across North America.  The tektites that fell in Georgia and South Carolina are classified as Georgiaites and are found nowhere else in the world.  Tektites from the Chesapeake Bay impact that landed in other parts of North America come from a different part of the earth’s crust and are not of the same composition as the Georgiaites.

A Georgiaite tektite.  It’s translucent green when held up to the light.

This map of Georgia shows where Georgiaite tektites have been found. They have been discovered in over 20 counties in Georgia and 2 in South Carolina, but 95% of them have been found in Dodge and Bleckley Counties.  Over 2500 have been discovered so far in exposed Eocene age sediments.

I’ve never visited west central Georgia, but this part of the state has at least 2 other sites worth visiting besides the Cove Dome: Warm Springs State Park, F.D. Roosevelt’s favorite vacation spot; and Sprewell Bluff which hosts a rare open oak savannah as well as the scenic bluff.  These attractions are a little off the beaten path but may be worth investigating.

Reference:

Albin, E.F.; et. al.

“Cosmic Impact in the Piedmont of Georgia? The Woodbury Structure”

Lunar and Planetary Science XXXVII (2006)

Advertisement

Tags: charnocktite, Cove Dome, Georgiaite tektite, pseudotachlytic breccia, west central Georgia, Westbury Impact Structure, Wetumpka Impact Structure