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The Manson Crater

4/11/2012

 
74 million years ago North America looked A LOT different! The crust of the Earth is broken into multiple “plates” that are driven by the heat and pressure from within the Earth.  The plates collide and pull apart every minute of every day in a process called plate tectonics.  It takes millions of years for any noticeable change to occur in the shape of the continents; however, almost every earthquake on Earth is caused by this violent splitting and crashing of the plates into one another. Below you can find images of what the Earth looked like at this time in history.
Picture
Here is (roughly) what North America looked like 70 million years ago. Image: Everything Dinosaur
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Here is a view of what the entire Earth looked like around the same time. Image: Wikipedia
75-70 million years ago falls within the Cretaceous period. This was a time of relatively warm climate, resulting in high sea levels and creating numerous shallow inland seas. These oceans and seas were populated with now extinct marine reptiles while dinosaurs continued to dominate on land.  There were new groups of mammals and birds and plants that appeared. The Cretaceous ended with a large mass extinction (the asteroid that killed off the dinosaurs) 65 million years ago. 

Now that we have the setting let us get to the "meat" of this blog post!  In the area that is now the state of Iowa in North America a large asteroid struck the Earth.  The impact was equivalent to 1,000,000 Hiroshima nuclear bombs, created earthquakes in excess of 10.0 magnitude, and generated tsunamis hundreds of feet high.  The asteroid dug a mile into the Earth in a fraction of a second and formed a crater about 24 miles in diameter.  “The impact is said to equal 10 trillion tons of TNT, resulting in an electromagnetic blast that incinerated anything within 130 miles and wiped out all life within 650 miles of the blast” (Pfeiffer).  In fact scientists once believed that this asteroid impact may have been the culprit that wiped out the dinosaurs.  Of course, we now know (at least we are pretty sure) that the asteroid that wiped out the dinosaurs struck 65 million years ago. 
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The circled area is the approximate region of Iowa and of the meteor impact.
Over time the crater eroded and glacial till covered it completely.  Today the area above the crater is completely flat; however, dozens of feet beneath the soil sits a giant crater and remnants of a meteorite.  The meteor was most likely 1.2 miles wide, made of stone, and was traveling 45,000mph when it struck the Earth. 
Today the town of Manson, Iowa sits on top of the crater.  For years engineers looked for a sustainable water source beneath the ground in Iowa.  The Iowa Department of Natural Resources thinks it knows how to find this sustainable water source:  When the meteor struck the Earth it instantly vaporized and pulverized the limestone in the ground beneath the impact. 

All of the limestone that was pulverized was able to mix with the groundwater deep underground and create the only natural soft water source in Iowa.  Engineers want to tap into this massive area soft water under the ground and they believe the softest of the water is located in the center of the crater.  Plans are being put together to drill into the center of the crater in hopes of creating a soft water well to supply Manson and neighboring Iowa towns with fresh water. 
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Here is a cross section of the underground crater. Image: IowaDNR
The task will not be simple, however.  Unless the exact center of the crater can be located there will be multiple attempts to find the softest of the water and multiple failures.  It may also prove to be difficult to drill through the rock layers outside of the crater center due to folding and faulting from the impact.

Hopefully engineers and scientists succeed and, in the process, gather more scientific evidence regarding the meteor and the massive impact it had on Cretaceous North America.  

Thanks for reading!

Sources:

http://www.igsb.uiowa.edu/browse/manson99/manson.htm

http://news.yahoo.com/blogs/sideshow/ancient-meteor-standing-between-one-iowa-town-water-154639667.html

http://blog.everythingdinosaur.co.uk/blog/_archives/2010/04/23/4512087.html

    Author

    I am an educator and avid student of Earth sciences and history. 

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