During the final week of October, students participating the archaeological dig at Crossroads’ Ida Bay Preserve found flakes, animal bones and pottery. They also found coral fossils which led some kids to dig with even more enthusiasm, hoping to find dinosaur bones. They didn’t. And they won’t, at least here in Door County.
Back 425 million years (or so) ago, the place we now call Wisconsin was covered by a warm, shallow sea. Conditions were ideal for fossil formation. Primitive animals such as corals secreted hard shells. Many were preserved in the dolomite which forms our bedrock.
Understand that the bedrock in our area is sedimentary, a type of rock that forms in layers. Now consider: if a layer of rock formed and then, another layer formed on top of it, which one is older? The bottom layer, of course. So if there are many layers (and here in Door County, there are many, many layers) the bottom layers are the oldest, the top layers are the youngest. Each layer is younger than the layer below it and consequently, fossils found in those layers should also be oldest at the bottom, youngest at the surface.
This makes sense and scientists have a name for it. Geologist (and as I learned last month, also archaeologists) call this The Law of Superposition.
The fossils the kids found are the remains of creatures that lived long before the Age of Dinosaurs.. So wouldn’t you think that in the rocks closest to the surface, kids would find dinosaur bones? That is, if dinosaurs were here. So were dinosaurs here? Scientists simply do not know.
It’s an unsolvable mystery. We don’t know what animals roamed or swam through ancient Wisconsin because there is a major gap in the fossil record. Almost 400 million years of geological evidence is missing. Scientists call this The Lost Interval.
We assume, but don’t know, that layers of rock continued to form. Much of this soft rock was probably eroded by water, and then, what was left was scraped off by Ice Age glaciers. Geologists can speculate, based on rock formations found in unglaciated parts of the country, but they will never have rock solid evidence whether or not there were dinosaurs here.
So kids participating in the No School Friday Family Program: Door County Fossils on Friday, November 20 at 2:00 absolutely will not find dinosaur bones. But they very well might find fossils of creatures millions of years older. The program begins with hands-on activities featuring the Law of Superposition and ends with a fossil hunt. Some of the models we will make are edible, so parents should call ahead 746-5895 if children have dietary restrictions. If weather makes outdoor fossils hunting impossible, we have an alternate plan.
Saturday, November 21, at 10:00, hike participants will explore the north end of the Ida Bay Preserve. Hikers should park at the small lot at the intersection of Canal and Buffalo Ridge Trail. The deciduous forest looks very different following leaf drop. The pace will be gentle and the hike will take about about an hour and a half.
Crossroads at Big Creek is a donor supported preserve welcoming learners of all ages to programs in science, history and the environment. The Collins Learning Center, located at 2041 Michigan Street in Sturgeon Bay, is open 2:00-4:30 daily and during scheduled activities. The Crossroads, Big Creek Cove, and Ida Bay Preserve’s trails are open to the public without admission charge.
Friday, November 20
2:00 No School Family Program: Door County Fossils
This free family program begins with hands-on activities featuring the Law of Superposition and ends with an optional fossil hunt. Some of the models we will make are edible, so parents should call ahead 746-5895 if children have dietary restrictions. If weather makes outdoor fossils hunting impossible, we have an alternate plan. Meet at the Collins Learning Center.
Saturday, November 21 10:00 Hike at Ida Bay
Hike participants will explore the north end of the Ida Bay Preserve. Hikers should park at the small lot at the intersection of Canal and Buffalo Ridge Trail. The deciduous forest looks very different following leaf drop. The pace will be gentle and the hike will take about about an hour and a half.