Sinkhole sucks in geologist
Post Independent Staff
Less than 24 hours after Jonathan White heard about the Colorado Mountain College sinkhole, he motored west to the Roaring Fork Valley to check it out.
“This is important to us,” said White, an engineering geologist with the Colorado Geological Survey in Denver. “When I heard about it, I wanted to see it … see it in relation to the local geography and topography.”
White said a four-foot-wide hole might have come first. The 30-foot-wide sinkhole now evident formed in a matter of seconds earlier this month, perhaps with a “poof” sound.
“I haven’t seen many spontaneous ones like this, not in Colorado. This is pretty rare,” White said Thursday morning as he and a handful of CMC geology students and staff members surveyed the Roaring Fork Valley’s newest attraction.
Colorado Mountain College staffers at the Spring Valley campus discovered the sinkhole, which is 20 feet deep, on Feb. 10, but geology instructor Garry Zabel told White that some students found it a few days before that.
“I heard a couple of kids jumped into it,” Zabel said.
The sinkhole sits on the Gates Family Soccer Complex between soccer fields 4 and 5. CMC maintenance crews put up temporary fencing to prevent the curious from venturing too close.
There’s a chance the sinkhole’s walls could collapse. The sinkhole rim is also undercut and unstable.
“There seems to be more undercutting,” student Eric Herth told Zabel and White. Pointing inside the hole toward its steep wall, Herth continued, “That slab wasn’t there a week ago.”
White had already jotted details in a yellow notebook and took pictures with his well-used camera when Zabel and his four students walked up a muddy road to the hole Thursday morning.
White told Zabel’s students the state Geological Survey is trying to build awareness of sinkhole risks here, because they occur more densely in the Roaring Fork Valley than anywhere else in Colorado.
“They can occur in Aspen Glen, Rose Ranch, Coryell Ranch, all the way to Carbondale,” White said as the students gathered around.
One student joked about golf courses chewing up the Roaring Fork Valley floor, and White retorted, “Golf courses are probably the best land use around here. With a sinkhole you can just fill it up and use it for a sand trap.”
Moments later, White scrambled across a load of fill material that CMC has dumped into the hole, and inched his way to the bottom to snap off a fist-sized soil sample from the wall of the sinkhole
Topside, White broke the tan soil in half and told Zabel, “This looks like reworked loess to me.” Loess (pronounced luss), he explained, is windblown dust.
“This is pretty interesting,” White said has he slowly turned the sample over and over. “I don’t see any basalt at all.”
The soccer field sinkhole is one of several in and around the CMC campus, and elsewhere around the Roaring Fork Valley.
“There’s one above the sewage treatment plant,” Zabel said, of the CMC plant, which is south of the soccer fields.
“At the Mt. Sopris rest stop, you can see them down at Coryell Ranch, with scrub oak growing inside,” White countered.
Less than a quarter mile southwest of the soccer field sinkhole, a sinkhole several hundred years old stretches 200 to 300 feet across and is 50 feet deep. “That large one, over there, is almost like a crater,” White said.
After White snapped his camera case shut, closed his notebook, and the kids drifted off to talk among themselves, White said his observations will be added to a Roaring Fork Valley sinkhole map the Geological Survey recently completed.
“This places another point on the map. It’s another piece of data for this area,” White said.
Sinkholes receive nationwide attention when they gobble up vehicles and houses, but Roaring Fork Valley sinkholes have yet to gulp down a Volvo or bite off someone’s garage. White said that local track record could change.
“As growth continues in the Roaring Fork Valley, the risk to structures increases. In an area with this density of sinkholes, you keep putting houses there and in time, someone is going to be impacted,” he said.
But White brushed off the worry that soccer players could fall into a sinkhole at the popular Gates complex.
“This kind of sinkhole is very rare,” he said. “I think there’s a better chance of getting hit by lightning playing soccer up here, than falling in a sinkhole.”
Contact Lynn Burton: 945-8515, ext. 534
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