Rockhounds rejoice
Rockin’ the Driftless goes prehistoric
By Emily Rocksvold
Emily Rocksvold identifies fossils commonly found in the Driftless region. Here she holds up a maclurite specimen. (Driftless Multimedia photo by Samantha Ludeking)

Emily Rocksvold is a Geoscience graduate of University of Iowa and Decorah resident whose enthusiasm for and knowledge of the unique fossils, flora and fauna of the Driftless is generously shared.

We live in an amazing area of the United States. You have probably heard it called the Driftless Region. It has this label because of a period of time when this land was not covered by glaciers, instead it was scoured by rivers and erosion for thousands of years. Those processes created the cliffs and river valleys we see today.

Before that time, about 470 million years ago, this area was a shallow ocean. Sediments and traces of living organisms settled to the bottom. Over those millions of years, the sediment became rock and some of those traces of life became fossils. The cliffs and bedrock in this area are full of fossils from that time period referred to as the Ordovician Period (485-443 million years ago).

Here are some common fossils you can find while out on a walk along almost any body of water or hillside

around Decorah. 1) Gastropods are much

like their modern descendants -snails and sea snails. They are incredibly similar to those we see today. Some have high spiraled shells, some have a flat

spiral. Whole eroded-out casts can be found, or cross sections of

the shells.

2) Receptaculites were colonial algae. They are commonly known as the dinner plate or sunflower fossil. Whole specimens are as big as a dinner plate and exhibit geometry that looks like the

Fossils

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