What draws so many school groups, families and researchers to Lilydale Regional Park along St. Paul's Mississippi River bluff?
Fossils. Lots of fossils.
Lilydale is one of the premiere fossil-hunting locations in the region. The National Park Service has identified the Mississippi River in the Twin Cities as potentially one of the best "paleo-parks" in the nation. The Park Service has asked local paleontologist Justin Tweet to conduct a study of fossils along the Mississippi.
"It's unique in the National Park Service," he said. "We don't really have this slice of rocks preserved well in other parks and we have Cretaceous rocks elsewhere, and Triassic rocks with dinosaurs elsewhere, but we don't have this particular slice of time, and this is the best spot in the Twin Cities for these types of fossils."
The following is an edited interview with Tweet by MPR News' "All Things Considered" host Tom Crann.
“It's a place where people can come and experience the natural history for themselves. ... There aren't a whole lot of places in the Twin Cities where you can do that. “Justin Tweet, paleontologist
TOM CRANN: What kind of fossils are you apt to find at Lilydale?
JUSTIN TWEET: The rocks in Lilydale are from about 450 to 460 million years ago. They represent animals that lived at the bottom of a shallow sea when Minnesota was actually south of the equator. There are brachiopods — small shells that look like clams. Lots of sea lilies. Lots of trilobites. And snails.
CRANN: What is it about this particular location that makes it such a unique area for fossils?
TWEET: The park at Lilydale used to be a brickyard — the Twin Cities Brick Company. And they ended up excavating several areas, so there's large amphitheater-like cuts in several places, and that exposes this fairly soft formation to view, so people can collect rocks more easily and also allows erosion to get at the fossils and work them out of the shale.
CRANN: We have heard consistently since the landslide that families and school groups visit Lilydale and take fossils home to study more closely. You need a permit to do that. Is removing the fossils a potential problem for researchers like yourself?
TWEET: There are thousands upon thousands of these invertebrate fossils and as erosion goes on, I'm sure that more fossils are swept away or destroyed by natural erosion than are taken by school groups. So that isn't a huge concern.
CRANN: Much of Lilydale Regional Park right now is closed off. No one has decided the future of this fossil-hunting area. Let's say it remains closed off for safety reasons. What have we lost?
TWEET: I was there as a Cub Scout back in the 1980s. It's a place where people can come and experience the natural history for themselves. They can come and pick up things and take them home and look at them. There aren't a whole lot of places in the Twin Cities where you can do that. For some people, it can be inspirational to be holding fossils in their hands and taking them homes for their own collections. It can inspire people to go on to careers in science.