Fossil Hunting in Iowa

by Tatyana Ivanov
Iowa's geological parks are full of treasures for fossil hunters.

Iowa's geological parks are full of treasures for fossil hunters.

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Imagine walking the ocean floor in landlocked Iowa. The prehistoric geological richness of Iowa can be explored by fossil hunting in the many geological parks of the state. Several environmental occurrences have revealed fossils dating back as far as before the existence of the dinosaurs. Surprising prehistoric discoveries can be made in Iowa.


One of the prime locations for fossil hunting in Iowa is in the northwest portion of the state, along a series of outcroppings called the Paleozoic Plateau. The Devonian Fossil Gorge, just outside of Iowa City, is included in this outcropping. This site was discovered in 1993 when a flood at nearby Coralville Lake eroded and exposed portions of the site. A subsequent flood in 2008 fully revealed the remainder of the site. Additionally, fossil hunters can hike along the Floyd County Fossil and Prairie Park located just outside of Rockford. This site is free and open to the public, featuring miles of hiking trails through the fossil-rich area.


It's hard to imagine that landlocked Iowa was once beachfront property. Approximately 375 million years ago, between the Cretaceous and the Cambrian eras, Iowa was located south of the equator and covered with warm, shallow seas. These prehistoric Iowa seas resembled the Caribbean Ocean today. As time passed, the ocean floor and floodplain sediment of ancient Iowa settled, fossilizing and imprinting the rocks with the remains of ancient sea creatures. The fossils found in northwestern Iowa are of the Devonian strata and are approximately 200 million years older than dinosaurs.


The Paleozoic Plateau outcroppings of bedrock located in northwest Iowa primarily consist of limestone created by the solidification of ocean floor sediment. Additionally, some of the rocks located in the northwest portion of the state of Iowa consist of silica-rich sandstone, dolomite and shale, which can be up to 3,000-feet thick at some locations. Because of the predominance of limestone, the area also has a thriving limestone extraction business that contributes millions to the state's economy.

Types of Fossils

The types of fossils found in Iowa's geologically rich environments are predominately from the Devonian strata, which primarily encompasses sea creatures living approximately 416 million years ago. During this era, the fins of certain fish began to evolve into legs. Thus, Iowa's geological history serves as an important link to the evolution of terrestrial creatures. Some of the sea-creature fossils found in Iowa geological parks include lobe-finned fish, brachiopods, crinoids, trilobytes and bryozoans.

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