Photo of the landslide on the Pinnacles that occurred Tuesday morning. Photo by Benny Molina.
(Dubois, Wyo.) – On Tuesday at approximately 11:30 a.m. the profile of the geological feature west of town known as ‘The Pinnacles’ was significantly altered by a massive rock slide. According to Adam Long, Brooks Lakes Lodge general manager, there was no warning, just a cracking noise followed by “a huge dust cloud” that completely blocked the view of the Pinnacles, followed by the ground rumbling. “There was dust everywhere, you could actually see and smell it from the Lodge,” he said.
The Pinnacles is one of the most photographed features west of Dubois and is featured in local and state tourism information.
In a phone interview with Central Wyoming College Geology professor Suki Smaglik, she noted that the Pinnacles formation was composed of very loosely consolidated volcanic rock known as volcanic breccias which, even without the unusually high amount of rain and snow, was unstable. Smaglik said the formation was laid down in the Eocene Era, some 50 million years ago from volcanic action. “The material there is from mountains that are now gone. The material is like what is found in the Cascades, it’s volcanic debris.” The CWC professor also said a contributing factor could have been a very wet September, but that’s just a possibility. “It’s not a surprise that a rock slide occurred,” she said, “they happen there all the time, but not on this scale usually.” Smaglik also noted that with additional snow, freezing and thawing, more rock slides could occur.
Brooks Lake Lodge maintenance manager Brian Miller witnessed the event, saying it ”felt like a huge earthquake” and sounded at first like a high powered rifle being shot. He said that the slide area is near the east side of the Pinnacles trailhead. He said he was immediately concerned for any hunters that might have been in that area. Miller’s wife, Antonia Armenta-Miller, executive chef at the Lodge noted, ” the breadth and width of the slide is just phenomenal.”
There are no reports of any injuries or of any missing people in the area.
Due to the government shutdown, information from the U. S. Geological Survey was not available. Officials at the State of Wyoming’s Geological Survey’s Hazards Program were out of the office and unavailable for comment.