Giant rock falls on highway north of Prairie Du Chien

Experts, locals say fallen rocks common this time of year

Locals know fallen rocks aren’t uncommon on bluff-side highways, but one found yesterday between Prairie Du Chien and Lynxville was something special.

“It was one of the bigger ones I’ve seen,” said Lynxville resident Brian Golbach.

The nearly car-sized rock was reported Wednesday afternoon, and crews had it gone by 7:30 p.m. that night. No one was injured, including the highway, but the concrete barrier was damaged. One lane was kept open during removal.

“If they say watch for rocks, you better watch for them,” said Eastman local Phil Dwornik. “They don’t put signs up for no reason.”

“The number of signs out there along that stretch of Highway 35 was doubled more than a month ago because of the temperature changes that were occurring because of the warm spell we had,” said WisDOT Regional Communications Manager Michael Bie.

Bie said maintenance crews regularly check the bluffs for fallen rocks.

“There are rocks that will become loose on a regular basis and in this case it was a significantly sized rock,” he said.

Paul Reyerson, assistant professor in the Geography and Earth Science Department at UW-La Crosse, said falling rocks ramp up in springtime.

“Water will get in the cracks and soils in the bedrock and it will freeze there. And when it freezes it expands, and expansion is what breaks this rocks up,” he said. “So this time of year, when the soil and the bedrock is so damp, that’s why we see these bigger rocks and more rocks in general falling off.”

Reyerson said this year’s weather pattern was the perfect storm for rocks to crack and fall.

“You’re going to get a lot more breaking of the rock when the temperature is hovering right around the freezing point and it’s very damp, so like what we had this past week. We can expect a lot more fracturing of the rock when that occurs,” he said.

Locals know it’s just one of the trade-offs that come with living in the bluffs.

“It’s one of the things about Prairie Du Chien, it’s a beautiful area but we kind of rough it out and tough it out,” said Dwornik. “You never know what you’re going to see down this way.”