Geology | St. Louis Public Radio

Geology

What is the story behind Natural Bridge Road?
AA Roads

If you’ve ever wondered where in the world the “natural bridge” in Natural Bridge Road comes from, you’re not alone. The answer is tied to Missouri's abundance of caves and the underground world of St. Louis.

It’s a question Joe Light, vice president of the Meramec Valley Grotto and member of the Missouri Speleological Survey, gets asked all the time. Several Curious Louis questioners have wondered the same thing.

The cliffs of the Tettegouche State Park in Minnesota are made of volcanic rocks that were formed by the Midcontinent Rift.
Wikimedia Commons | Smokemob

About five years ago, Doug Wiens, a seismologist from Washington University in St. Louis, went knocking on the doors of farmers in Minnesota and Wisconsin. He asked them if they would let him and his team of geologists place seismometers, devices that measure the earth’s movements, on their land.

The farmers were a little suspicious.

“‘Why are you doing this here? Are you exploring for oil? Nobody’s done anything like this before,’” Wiens recalled them asking. “And so, we would show them this gravity map and we’d say, ‘Well, there’s this really unusual feature here and we want to study that.’”

The USGS will collect data on mineral deposits in the St. Francois Mountains using a Piper Navajo airplane with auxiliary wingtip pods and tail stinger magnetometers.
Terraquest Ltd.

The U.S. Geological Survey is searching for commercially important minerals in southeastern Missouri. But the researchers won't be using any shovels or pick-axes: All the data will be collected from a small, low-flying plane.

The aerial survey is part of an on-going project to study the geology of the St. Francois Mountains.

Look at this map, and notice that deep, deep in the Republican South, there's a thin blue band stretching from the Carolinas through Georgia, Alabama and Mississippi. These are the counties that went for Obama in the last election. A blue crescent in a sea of red.