The coordinates take you to the entrance to Dunning’s Spring Park. You will need to walk the blacktop road a short distance to get to the stone arch bridge near the waterfall.
This is an EarthCache. There is no physical cache to find. Instead, in order to log a “Found It” on this cache, you must send the answers to the questions to the cache owners.
The stone arch bridge was completed in 2017 and is similar to one that was here more than 140 years ago. This unique bridge features dry stonewalling, which means there is no mortar between the joints. The Decorah Park-Rec Board decided to replace the aging replacement wooden bridge with a bridge similar to the original one that was here when there was a mill. Some of the rock used in the bridge was salvaged from the former East Side School building.
The honeycomb limestone used in the area connecting the bridge to the trail came from veins found in area quarries from the Galena Formation. The delicate honeycomb limestone contains some nice fossil specimens. The fossils found in the Winneshiek county area are from the Ordovician time period about 450 million years ago. These specimens of marine life flourished in the warm, shallow seas that once covered Iowa. The fossils formed when the plants and invertebrate animals died in this watery environment and were buried in the mud and silt. Soft tissues quickly decomposed leaving the skeletal tissue, hard bones, or shells behind. Over time, they were buried in layers of sediment. Sediment continued to build up. Heat and pressure hardened the sediment into the limestone rock you see here.
The types of fossils that you can find in this area include Brachiopods, Gastropods, Crinoids, Cephalopods, Bryozoans, Receptaculites, Horn Corals, and Colony Corals. We are going to focus on some of the fossils that you can see here. The photos of fossils were taken either on the bridge, or in the honeycomb limestone that leads from the bridge to the trail. You will need to find the fossils and then tell the cache owners where you found them.
A. This picture shows an imprint from a Brachiopod. Brachiopods look like seashells and lived in two hinged shells.
B. This is a picture of a Gastropod, or sea-snail, called a maclurite. These marine animals could only be found in the sea. It moved along the ocean floor using its foot that could be pulled all the way into their shells.
C. This is also a Gastropod, but a spiraling gastropod called Hormotoma. There are several great examples of these on the stone columns at the entrance to the park.
D. Crinoids, often called sea lilies, are actually animals related to starfish that lived long ago. They lived anchored to the sea floor like lilies.
E. Bryozoans look a lot like bones, but are actually little tiny animals. These Branch Bryozoans grew together to make each fossil. The name means “moss animals” because they can resemble mats of moss.
F. Receptaculites look like fossilized sunflower heads but are actually mats or colonies of algae that grew into the shape of a plate.
This picture shows the area where these fossils can be observed. The numbers show the specific location of one of the fossils.
1. Your job will be to match the numbers 1-6 in the photo to the letters A-F of the fossils telling where each one can be found. Then click on "Message this owner" and send us your answers.
2. Post a photo of yourself or a personal item near the bridge.
As always, respect the environment. Do not remove any of the fossils from these locations.
If you are doing Adventure Labs, one of the stages of the Adventure Lab "Decorah: A Driftless Adventure" is nearby.
Permission to place this EarthCache was given by Andy Nimrod, Director of Decorah Parks and Recreation.