Have a question about Iowa geology? Click on the items below for answers to some of the more commonly asked questions.

Did dinosaurs once live in Iowa?

The simple and unqualified answer is “Yes, without a doubt!” Dinosaur fossils have been found in several states adjoining Iowa (Nebraska, Minnesota, Missouri, and South Dakota). But the actual evidence for dinosaurs in Iowa is limited to only a few fossils.

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What fossils can I find in Iowa?

Many people become interested in geology after finding fossils. Iowa has quite a few well-known fossil-bearing rock formations, and fossils from around the state have found their way into museums worldwide. Most Iowa fossils were once marine animals, reflecting Iowa’s history as a vast, shallow, warm sea.

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Have any meteorites fallen in Iowa?

Yes! The arrival of the first of Iowa’s historic meteorites in 1847 was announced with a great blast, described as sounding like the rolling of “distant thunder” followed by “three reports … in quick succession, like the firing of heavy cannon a half mile distant.” C.W. Irish, a civil engineer, reported that the explosions were “distinctly heard at Iowa City, 22 miles south from the place of the fall, and great was the alarm caused by them.”

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What are geodes and where can I find them?

Geodes form in voids (holes) in the bedrock. Over time, minerals form in these voids from the precipitation of minerals out of the water flowing through the bedrock. The type of minerals that forms depends on the chemistry of the water flowing through it. Geodes are common in the southeast corner of Iowa.

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What are those strange boulders in fields?

Peculiar, irregular, and uncommon are words used to describe one class of Iowa rocks — glacial boulders or “erratics.” Geologists define erratics as stones or boulders that have been carried from their place of origin by a glacier and then left stranded by melting ice on bedrock of a different composition. In Iowa, glacial erratics are commonly found where glacial deposits occured at the land surface, primarily in the north central and northeastern parts of the state.

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Are there caves in Iowa?

Yes! Northeast Iowa is dominated by karst topography, which is a type of landscape dominated by caves, sinkholes, and natural springs. You can see many of these features in parks in this part of the state. The most popular public park for caving is Maquoketa Caves State Park.

Read more about Iowa’s karst topography and check out the field guide to Maquoketa Caves State Park.