Thursday, August 4, 2011

Devonian Fossil Gorge – University of Iowa

(Iowa City, IA) Hi 87 Lo 69 – We got out and about today. It was still humid, but it was cloudy so it wasn’t that "hard to breathe" feeling.

We started our day by heading out to see what’s around this COE park. We went to the visitors center, where they have a small museum about the geological features of this area. While there we talked to a park ranger who was very interested in our full time lifestyle. He told us that they're always looking for workers at COE parks nationwide, and they hire a lot of RV full timers.
Right here in the park about a mile from us is Devonian Fossil Gorge. To best explain what the gorge is, and what caused it, I'll give this direct quote from the website:  

"Historic floods during the summer of 1993 poured over the emergency spillway at Coralville Lake and eroded a deep channel into the underlying bedrock deposits. It is now possible to walk across acres of Devonian-age sea floors and get a first-hand look at features normally hidden from view or glimpsed only in vertical cuts along roadsides or in quarries. The exposed rocks provide a rare opportunity for public observation of Iowa's geologic past. The floor bed is over 375 MILLION years old."

We got a pamphlet at the visitors center with a guide to the features of the Gorge, which were marked with numbers embedded in the limestone. At the entry plaza are displays telling about the dam, the floods, and fossils of the Gorge. (Click on photos to enlarge.)
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This is one half of the area that encompasses the Gorge, looking from the entry plaza.
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Some of the fossils in the Gorge are Brachiopods, Crinoids, Trilobites, and various Corals (all about 200 million years older than the dinosaurs).

This is an example of a Crinoid fossil. Called sea lilies, crinoids are related to star fish, and lived anchored to the sea floor by flexible, segmented stems.
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Several thin fractures in the limestone are filled with white to clear calcite crystals. It was really prominant in several of the rocks.
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Colonial corals from the overlying biostrome collapsed into a cave and were cemented to the cave floor. Erosion exhumed the cave and exposed the fossils and cave walls.
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Brachiopods, folds and fractures. Abundant brachiopods can be seen. In the background several fractures and large folds in the limestone show stresses that affected these rocks in the geologic past.
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A large variety of fossils can be seen here, including brachiopods, crinoids, bryozoans, and horn corals.
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This is a view of the river bed, as seen from one end of the Gorge.
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We spent about an hour looking around the Gorge, and it was fascinating to see evidence of life from 375 million years ago! We then drove around to see some other areas of the Coraville Dam Complex. Here's a view of Tumbleweed from the other side of the river.
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Looking up at the side of the earthen dam. A local guy we met said that during the flood of 2008 water rose eight feet higher than the dam, and you could see lots of fish going over it. (Note the car at the right on top, to show the size.)

And this is looking down from the road that goes along the top of the dam. Our campground is on the left bank of the river, just about where the river disappears around the bend.
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There are five campgrounds in the Dam Complex. We drove through them all. Some have full hookups (water, sewer and electric), but most have only electric. And most of the sites have concrete pads, which is very nice!
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It was time for lunch, so Jim did a search on our Garmin GPS and found our favorite place (Culver's) nearby in Coralville. After filling our tummies with butterburger and tenderloin, we headed to Iowa City to see the campus of The University of Iowa.

Kinnick Stadium, home of the Iowa Hawkeyes football team.
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One of the buildings of the UI Medical Complex.
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Not sure what this building is, but it's pretty.
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The UI Field House, which contains the practice facilities for the Hawkeye basketball team.
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The campus is very pretty and we're glad we got to see it. It’s a Big Ten school, so we can't officially be Iowa fans because our son went to University of Illinois, another Big Ten school. :)

It looked like rain was on the way so we came back home and settled in for the rest of the day. The storm system ended up going north of us.  It was a great day of exploring, and we still have a few more places to see.


Weldon and Sandy said...

One fine post. The photos as usual are outstanding.

Weldon and Sandy said...

What a fine post. The photos as usual are outstanding.

Sam&Donna Weibel said...

Love all the info. Always have found fossils fascinating. Thanks.
Donna W