Des Plaines crater facts for kids
The Des Plaines crater, sometimes called the Des Plaines disturbance, is a special place in Cook County, Illinois, United States. Scientists believe it is an impact crater. This means it was formed a very long time ago when a large object from space, like a meteor, crashed into Earth. Today, this ancient crater is hidden deep underground. It lies beneath the eastern part of the city of Des Plaines, which is a town near Chicago.
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What is the Des Plaines Crater?
The Des Plaines crater is a large, circular area of disturbed rock. It was created when a space rock hit the Earth with incredible force. Over millions of years, the crater got covered up by layers of dirt and rock. This includes a thick layer of material left behind by glaciers, called glacial till. Because it's buried, we can't see the crater on the surface. Instead, scientists study it using special tools that look deep underground.
How Big is the Des Plaines Crater?
The Des Plaines crater is quite large. It measures about 5.5 miles (8.9 kilometers) across. This means it covers an area of about 25 square miles (65 square kilometers). Imagine a circle that big! It's buried between 75 to 200 feet (23 to 60 meters) under the ground. That's like being buried under a 7 to 20-story building!
How Old is the Des Plaines Crater?
Scientists are not completely sure how old the Des Plaines crater is. They think it formed sometime between 280 million years and 2 million years ago. This wide range means it could have happened during the Permian period or even more recently. Finding the exact age of buried craters can be very tricky.
How Was the Des Plaines Crater Discovered?
The first hints of this hidden structure came in 1893. People drilling for water wells in the area noticed something strange. One well, dug about 1,600 feet (488 meters) deep, did not find any water. This was very unusual for the area. The rocks underground also looked different from what they expected.
For a long time, scientists didn't know exactly what this strange underground area was. They called it a "cryptoexplosion structure" or "cryptovolcanic structure." These names meant they knew something big had happened, but they weren't sure if it was from a volcano or some other unknown explosion.
Evidence for an Impact
Over time, more studies were done. Scientists used special methods like well logs and seismic surveys.
- Well logs are detailed records of the rock layers found when drilling a well.
- Seismic surveys use sound waves sent into the ground to create a picture of the layers beneath.
These studies showed that the rocks deep underground were broken and tilted. There were many faults, which are cracks in the Earth's crust where rocks have moved. Some rocks had moved up or down by as much as 600 feet (183 meters)!
The biggest clue that it was an impact crater came from finding shatter cones. Shatter cones are unique cone-shaped rocks that only form under the extreme pressure of a meteorite impact. Also, the center of the structure was pushed upwards, which is common in impact craters. All this evidence helped scientists confirm that the Des Plaines crater was indeed formed by a space rock hitting Earth.
