Posted: May 18, 2020
Fossil Hunting in the Driftless
I have been waiting for spring to arrive in full force and when it finally did, I was ready. My binoculars and morel bag were ready to go. I’d brushed up on my spring wildflower ID and frog calls. I was so excited to get outside and share everything with my family!
Out we went, and I showed them all the changes that come with spring. Look, here’s a spring beauty blooming! And that’s a northern flicker just returning! And listen to that chorus frog singing!
Their response to my enthusiasm? Any parent can probably guess: “That’s great, Mom. Can we do something else now?”
Shucks. How am I going to get outside enjoying the things I love when I can’t interest my young kids in it?
Luckily, we hit on something they do seem to love (at least right now): fossil hunting. Searching for ancient fossils is as close to the exact opposite of watching daily spring changes as you can get, but at least they both take place outside.
And spring is a great time to search for fossils. Winter’s freeze/thaw cycle is constantly pushing new fossils up from below the soil surface; spring’s heavy rains erode more fossils out of riverbanks and wash dust, mud, and debris off those already exposed; and there’s not yet much plant growth to work around.
Iowa has fossils from a wide time period, but the fossils you can find in Winneshiek County are about 450-million-years old, from the Ordovician time period. Unfortunately for most kids, and a few grown-ups I know, we don’t have dinosaur fossils in Winneshiek County. Our fossils are all ocean-dwelling creatures that were trapped in the layers of sediment that built up on the bottom of the oceans that once covered Iowa and much of North America.
But that makes fossil hunting here even more fun! In land-locked Iowa, we can find sea-snail gastropods, brachiopods that look like seashells, and squid-like cephalopods (or sesame pods as my kid calls them; please don’t tell him otherwise). Other fossils trick us into thinking they are something else. Bryozoans look like tiny, holey bones but were really colonies of hundreds of tiny animals. “Sunflower” corals look like snakeskin but were mats of algae.
And the coolest thing of all? Everything is really, really, really, unimaginably old.
While there are probably specific sites that are “prime” fossil areas, we happen to live in a part of the state where you can find fossils just about anywhere that’s rocky. My family was walking up a road ditch the other day and my six-year-old found a cephalopod the size of his arm. He is very proud of that find, mostly because the rest of us walked right by it.
Some good spots to check are sand or gravel bars along rivers or creeks, rocky ravines, exposed bluff faces, or dry creek beds. Focus on areas with lots of limestone (tannish rock; usually in bluff faces) or shale (grayish and flaky). As always when exploring outside, be sure to respect private property. For the most part, you can keep fossils you find on public property, except at state preserves where you cannot remove anything.
So, this spring my family is making sure our outside adventures include places that might have fossils. I’ll poke around and flip a few rocks, but I’m pretty easily distracted by birds and flowers. It’s a good thing I’ve got my six-year-old staying focused and catching the many fossils I miss.
Download a guide to the Fossils of Northeast Iowa.