Fossil hunters

Aaron and Maisie have been getting interested in geology lately. They pick up rocks when they're out on walks and try to identify them when they get home. I'm always happy to encourage an interest in science, so on Sunday morning I suggested a field trip to go hunt for fossils!

We went to a St. Paul city park on the Mississippi called Shadow Falls that's known as a good place in the cities to search for fossils. If you want to go, it's right at the western end of Summit Ave., by the WW1 monument. There's free off-street parking, yay!

Once you get down off the main monument area onto the trails, there's also some pretty spectacular geology! This is taken right below the monument's safety rail. You can see layers and layers of limestone:

Here's the reason for the safety rail:

I'm not sure how high up we were there at the top of the bluff, but it was pretty dang high.

At this point we hadn't gone far at all, but we had already found our first fossils!

This is a hunk of limestone with some fossils that are pretty typical of what you find in the area. They date from the Ordovician time, 505-438 million years ago, when the area that's now Minnesota was covered by a shallow inland sea and 10-40 degrees south of the equator. So you end up with a lot of fossils from small marine organisms. The round thing you see in the limestone is part of a stem from a crinoid, a family of sea lilies that are related to sea urchins and sea stars. There are other little fossils in there too but they're hard to see in the picture!

Aaron scouted out some trails to get down to the riverside, north of the falls. I don't have pictures from the hiking part because the trails were a little narrow and steep, so not exactly good picture-taking! But we all made it down to the river.

Yes, bunny ears. It was Easter after all!

From the riverside you could see the different rock layers that make up the area. There's the limestone on the top, followed by shale (which holds most of the fossils). The white on the bottom is a huge layer of sandstone - it's extremely soft, so the graffiti here is carved in instead of written on the rock.

At the riverside, we searched for fossils. Aaron was an AWESOME fossil hunter and made some excellent finds! Maisie took notes in her field journal, drawing pictures of animals we saw and the different shapes of shells we found.

She did a great job of documenting all our finds.

We also poked around a little bit up and down the shore, looking at the different rock formations. One area had these HUGE slabs that were clearly sliding down towards the river. They were really fun for the girls to climb up and around.

HUGE!

Eventually it was time to head back up. So up up up we went...

back up to the monument. We checked out our finds, had a snack, and compared field journal notes.

So here's a representative sample of what we found!

Going clockwise - the top rock is that big piece of limestone with embedded fossils. Next is a piece of shale that Maisie thought looked like a dinosaur tooth. Then another smaller piece of limestone with fossils, followed by a big piece of black something or other... very smooth and shiny! Then you can see some of the shells that we found.

We weren't able to identify everything, so that afternoon the girls and I took our finds to the science museum, to get some identification help.

At 9:00 in the picture is what we initially thought was a fossilized shell. If you look closely, it has lines on it that look like those on the kind of shell a scallop would have, if that makes sense - radiating out from a point. We took it to the science museum, though, and the scientist there identified it as actually a trace fossil! It's a piece of stone that used to be sand that had a shell on top of it. Cool, hey? Then there are the two little things that look almost like vertabrae. They are fossilized bryozoans - a colonial organism very similar to coral. If you looked closely you could see that they're covered in tiny pores, each of which was the home to one tiny animal.

At the end of the day Maisie said, "We learned so much today!!" Both girls really had a lot of fun. They loved hiking, seeing the animals, and talking about the rocks. Today my legs are sore, sore, sore. But it was a lot of fun and an experience we will definitely repeat.