Knowing what they know, geologists tend to be skittish about the prospect of living under Billings' beautiful but unstable Rims, whose slopes are thick with slabs and boulders shed over thousands of years.
Jay Shearer, a past president of the Montana Geological Society, said he came close to buying a house under the Rims some years ago.
“I really wanted to,” he said. “I just decided I couldn't sleep up there.”
Ben Chorn, who measured the movement of partially detached slabs of sandstone on the Rims as a geology major at Rocky Mountain College last year, expressed similar reservations.
“I can see the aesthetics of it, but if you want your house to last 50 or 100 years, it might not be the best place,” he said.
The danger imagined by geologists was vividly manifest last month, when a 50-ton boulder smashed into the home of Jon Lodge and Jane Waggoner Deschner, demolishing half the house and pushing the whole structure two feet forward on the foundation.
“Those rocks are going to keep coming down. It's just hard to predict when,” said Jon Reiten, a hydrogeologist in the Billings office of the Montana Bureau of Mines and Geology. “They're crumbling and weathering. Gravity rules and eventually wins.”
Building high up on the slopes below the Rims is a relatively recent phenomenon. As the valley filled up and people of means wanted a building lot with a spectacular setting and expansive vistas, development crept closer and closer to the Rims. It's hard to imagine anyone building in the shadow of those Rimrocks amid all those boulders without, to some extent, assessing the risks of doing so.
But there is risk everywhere. Drunk drivers crash into more houses than boulders do, and even for houses under the Rims, lightning could be as likely as falling rocks. For that matter — and getting back to geology — there is the purportedly inevitable explosion of the Yellowstone caldera and the resulting obliteration of large swaths of Montana, Wyoming and Idaho.
Jim Koessler, who has lived under the Rims since 1997, said he and his wife, Eva, gave some thought to the danger of falling rocks when they bought their house on the upper end of Harrow Drive, but that consideration was outweighed by the beauty of the setting and the feeling of rural solitude just minutes from downtown Billings.
“Stuff happens,” he said. “That's part of life. Neither of us worries about it.”
The Koesslers are literally surrounded by the Rims, or fragments of them. Boulders are strewn about their backyard, and the stairs leading to their front door wind up through what appears to be a massive boulder that came to rest there in the past and then split in two. In Jim Koessler's home office, one wall was built around a portion of one of those sandstone behemoths, bringing the outside in.
When they bought the house, Jim Koessler said, the only geological question they asked was whether the foundation was solid. It was, having been built on bedrock.
“That was our main concern,” he said. “If a rock comes down, it comes down.”
David Lopez, a retired geologist with the Bureau of Mines and Geology, produced a map in 2003 that shows the “areas of potential rock fall in the Billings area.” Basically, those areas include all of the Rims that border Billings on the north and east, plus a small stretch of cliffs in the Alkali Creek drainage.
Forces of nature
The Rims regularly shed boulders and slabs of rock because they are composed of erosion-resistant Eagle sandstone that sits atop the easily eroded Telegraph Creek Formation. As the ground beneath the Rims erodes, the undermined ledges break off and go tumbling or sliding down the slope.
The effects of erosion and gravity are compounded by freeze-thaw cycles and the wedging action of root systems, which widen joints that open in the Rims. Reiten said the heavy rains of last spring and summer may have made the Rims more susceptible to rock falls this year.
The human element
Human activities, of course, could also play a role. Lodge and Deschner, whose house on Granite Avenue was virtually destroyed on Oct. 9, filed suit in late October against the state of Montana, claiming that a culvert under Highway 3 atop the Rims, installed by the Department of Transportation, directs water to flow into a crack in the Rims where the slab above their home eventually peeled off.
The lawsuit also names the city of Billings, which owns the parkland encompassing that stretch of the Rims, and their insurer, Brickley Insurance Agency. The suit says the insurer has not made a determination on whether they are entitled to coverage because “an expert analysis of the incident” has not yet been completed.
Barry Conver, with Conver and Winchell Insurance in Billings, said people living under the Rims would need to add “earth-movement coverage” to their policies. That would cover earthquakes, landslides and rock falls. He recalled one client from seven or eight years ago who bought a house with a backyard full of boulders and was told that earth-movement insurance would cost an extra $400 a year.
“I think he put it on for a year or two and then took it off,” Conver said. “A lot of people see it (the danger of falling rocks) like a flood and say, 'I'm not going to pay for flood coverage.' ''
Conver offered some simple advice: “Anyone who lives under the Rims needs to have a conversation with their insurance agent.”
Billings Mayor Tom Hanel, who is also a real estate agent, likewise had some advice for people looking at a house beneath the city's most distinctive natural feature. He suggests thoroughly investigating the property from below and above, looking at the likelihood of rock falls, and he also recommends getting advice from a structural engineer.
Hanel said he always tells potential buyers of the hazards of living near the Rims. “I go one step further and have them sign a disclosure statement,” he said.
Asked if such disclosures are standard practice, Hanel said, “I hope so, because there's a great amount of risk that lies with the real estate agent who doesn't make the proper disclosures.”
Candi Beaudry, director of the city-county Planning Department, said there are no setback requirements from the Rims in subdivision or zoning regulations, but geotechnical reports are required for all subdivisions and building permit applications. In a development near the Rims, standard wording in the Subdivision Improvements Agreement would say: “Lot owners should be aware that there exists a potential for rock falls or slides within the subdivision due to the proximity of the Rims.”
Doug Clark, a geologist who sits on the Yellowstone County Planning Board, said he wasn't sure how significant such a warning is.
“How many people when they move in there read the Subdivision Improvements Agreement, I can't tell you,” he said. “Probably not very many.”
The price of solitude
In some cases, the very signs of potential danger are what make the lots so attractive.
Wayne Nelson lives near the top of Ronan Drive, a few blocks east of Montana State University Billings. Much of his backyard is occupied by a house-size rectangular chunk of sandstone that actually rises above his house.
“That's why we bought the house about five years ago,” he said. “My wife called me at work and said, 'You've got to see this house.' And this” — he gestured toward the giant rock — “is what we were looking at.”
Nelson said when he thinks of where he lives, he thinks of the peace and quiet, and of the micro-climate created by the massive presence of the Rims.
Even if another slab were to fall off the Rims, he said, it would have to take out his neighbor's house and somehow get past the giant slab in his backyard. He calls it his “bumper.”
Contact Ed Kemmick at firstname.lastname@example.org or 657-1293.