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Professors Discover Rare Fossils in Pierce County

By Kate Smith
University Communications

Fossil UWRFDEC. 8, 2008--When University of Wisconsin-River Falls geology Professor Bill Cordua received a phone call from a local landowner about an unusual rock formation on his property, he could not have guessed their discussion would lead to the discovery of two rare Cretaceous-age fossils.

The fossils, which include two leaf impressions dating back to the Cretaceous period (from 65 million to 144 million years ago), were found on the property belonging to a geologist from the Minnesota Pollution Control Agency, Steve Thompson.

Thompson, who lives southeast of River Falls, was excavating on his property when he noticed an unusual sandstone formation near the edge of the area where he was working. “I knew the strata of the area, and this was not in the normal sequence,” Thompson said.

Intrigued by his discovery, Thompson called the UWRF geology department and asked if anyone could come to his property and take a look at the formation.

Cordua received the call and recruited several of his colleagues to visit the site. Geology Professor Kerry Keen was one of the first to visit and view the area. Within minutes, he discovered an impression of a leaf in the unusual sandstone formation, as well as fragments of wood. Keen explained that the discovery is significant because it is extremely rare to find fossils from the Cretaceous period in western Wisconsin.

“Most of the rocks we find in western Wisconsin are from the Ordovician period, which ranges from 450 million years to 500 million years ago. Also, most fossils we find here are marine fossils; there is no other reference to plant fossils from that [Cretaceous] time period in western Wisconsin.”

After making the discovery, Keen returned to the site with fellow geology Professor Mike Middleton and several others in the geology field. On that trip, the group found a second plant fossil in Thompson’s sandstone formation. From there, the fossils were taken back to UWRF, where the professors began work on identifying them and promoting their discovery to the geological community. In order to promote the find,

Keen, Middleton, Cordua, Thompson, UWRF geology Professor Bob Baker and UWRF junior geology major Amy Nachbor of Maple Grove, Minn., worked together to author a paper and create a poster on the fossils and presented them at the regional meeting of the Geological Society of America in April.

The professors have also displayed the fossils themselves at other places, including Chalmer Davee Library during the UWRF Celebrating Research, Scholarship and Creative Achievement event. Keen hopes that in sharing the discover it will bring awareness that there is a rich geological history in the River Falls area, and that there may be something unique in one’s own backyard.

“I would hope that someone could find an impression of dinosaur footprints or other plants,” Keen said. “That’s the fun thing of geology. You never know what discoveries are around the corner.”

The fossil samples are housed in the UWRF paleontology collection and are available to view by appointment. Contact Middleton at 715-425-3139 or for more information.


Last updated: Thursday, 22-Apr-2010 16:09:20 Central Daylight Time


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