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Today is September 16, 2021

Mississippi Seen

Rocks of the ages

By Walt Grayson

Rocks of the ages

Some of the rocks tell a story of ancient oceans - like this seashell fossil.

We took a tour of the canyons out west a few years ago. Most of the time we were in southern Utah. It is a beautiful part of the nation. The exposed layers of nature fascinated me. If you ever get the chance to go see it, go. Plus, with all of the red rock and the vegetation-less terrain, it will save you from ever having to go to Mars.

We don’t have those kinds of exposed layers of creation here in Mississippi. Well, with a few exceptions. Red Bluff in Marion County is about the best we have. Its alternating strata of river graves and clays and sands make up an exposed eroded hillside. A geologist can read the rocks and tell the story of how they got here.

James Starnes is a geologist with the Mississippi Department of Environmental Quality. I follow him on Facebook. In addition to being a talented and creative photographer, he has also been posting some interesting finds he has made in some gravel pits in west-central Mississippi under the loess bluffs of Warren, Hinds and Yazoo counties. The multiple layers of ancient rocks and sands are exposed here because of the digging. Since we don’t have thousands of feet of mountainside to display it, if you want to see the onion layers of the earth here, you have to dig for it. And a rock quarry is a great place.

The topsoil in the bluffs, maybe up to a few hundred feet deep, was blown in after the last ice age from dust and dirt picked up from melting glaciers out west. Under that are layers of gravel deposited during the ice age before it, as melting ice sheets up north created the ancestor of the Mississippi River, meandering all over the place leaving deep layers of sand and gravel over a wide area. The rocks left here came from glacier-cracked bedrock as far away as Canada. James says a geologist can trace the gravel back to its origin by rock type.

The rarest rocks they find are those that have had one side shaved flat as it sat under moving glacier ice. Recently, they have found pieces of petrified wood that have been glacier-shaved, too. Prior to this, the thinking was the wood became petrified in the gravel deposits about the time the rocks were laid down. But the flat surface on some of the wood means it was already stone before the time of the glaciers. This may cause a re-assessment of the age of the gravel deposits.

Sometimes, we tend to think of history beginning with maybe the Civil War. Or perhaps the colonial period. And ancient history going back to when the Native Americans got here. But if you want to study our real ancient history, dig a little deeper. A hundred feet or so deeper. And you will find fascinating stories carved in stones.

 

Walt Grayson is the host of “Mississippi Roads” on Mississippi Public Broadcasting television and the author of two “Looking Around Mississippi” books and “Oh! That Reminds Me: More Mississippi Homegrown Stories.” Walt is also a reporter and 4 p.m. news anchor at WJTV in Jackson. He lives in Brandon and is a Central Electric member. Contact him at walt@waltgrayson.com.

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