Limestone Bluffs of Eden Valley Refuge

The images from Eden Valley Refuge highlight the exposed limestone outcrops. Limestone is a sedimentary rock and is formed by an accumulation of skeletal fragments of marine organisms. The marine organisms were living in a shallow, tropical sea covering Iowa around 430 million years ago. The fossils present in the images from Eden Valley Refuge consist of brachiopods, corals, and crinoids.

• Why are fossils found in limestone bluffs/outcrops in Iowa?

• What is limestone?
• What are fossils?
• What is the history of Iowa’s landscape?

Students could:

• View the Bedrock Geologic Map of Iowa to determine the age of bedrock in different areas of the state.
• Research Iowa’s geology to understand the landforms and landscapes of Iowa.
• Identify fossil species found in Iowa.
• Visit a local state or county park, preserve, or recreation area with limestone outcrops and identify fossil species.

• National Resource Conservation Service | Iowa Geological and Water Survey: Bedrock Geological Map of Iowa: This source from the Iowa Geological and Water Survey is a Bedrock Geologic Map of Iowa.
• Iowa State University Extension: Landforms and Geology - Iowa's Nature Series: A free PDF booklet detailing Iowa geology, fossils and landforms.
• Iowa Geological Survey | Fossils: This source from the Iowa Geological Survey provides photographs and descriptions of fossils found in Iowa.