Ice tower

It’s a familiar sight every winter as you look up at the sheer rock along Lake area highways. Once the air turns cold, spectacular ice towers cascade down the rock face like a frozen waterfall. They’re beautiful to look at, but where do the Lake's ice cliffs come from and are they any danger to drivers?

A simple meeting of rock and water forges these ice towers. The bedrock that makes up the rock walls is full of small fractures that groundwater runs through. Usually this water flows out of the fractures in the rock face without notice, but in the winter the water meets the frigid air and freezes. This process repeats over and over as more water flows through and freezes. Giant icicles slowly form.

The most stunning of these formations at the Lake is probably the ice mass on the cliffside beneath Eagle's Landing: alongside westbound Highway 54 just after the exit for Lake Ozark and Route 242.

The icicles themselves aren’t dangerous to drivers, but the effect that water and ice has on the rock can cause problems. A rock wall collapse in December of 2019 brought rocks and rubble down onto Highway 54, scattering major debris across both lanes of traffic. Thankfully no one was hurt, but several cars were damaged. Although it’s impossible to know the exact cause of the collapse, ice may have been a factor.

“Because water expands in volume when it freezes, this can lead to an increase in the mechanical weathering of the rock,” said Dr. John Hogan, a geology professor at with Missouri S&T, “Ice forming along fractures in the rock faces can promote large blocks to spall off and tumble down towards the road which is very dangerous.”

A rock collapse like the one on 54 is very rare according to Bob Lynch, Area Engineer with the Missouri Department of Transportation (MoDOT). Lynch says anticipating such an event is challenging.

"The one on 54 was a sudden release," Lynch said. "It was deep inside the rock bluff so there were no visual things to tell us that something was going to happen there. A lot of it is what’s the makeup of the rock inside are there fracture zones that you can’t see because it’s so deep in the rock cut, you just don’t know if it’s there or not. It’s a very difficult thing to determine."

According to Lynch and Hogan, prevention is the primary policy for avoiding rock wall collapses by analyzing the rock before cutting for highways and determining that it’s safe for construction.

"That’s part of our initial investigation when we’re building the project, we determine what kind of rock is there and if it’s able to sustain a vertical face like that and our geologists help us determine that," Lynch explained. "That’s why there's a rock bluff there: it’s sound rock and can keep its shape."

The greatest danger to drivers, Lynch said, is the temptation to grab a cellphone and snap a photo of the towering ice cliffs. Leave that to your passenger.

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