Glenwood Springs rocks, says Zabel
From where Garry Zabel and about 100 rapt listeners stood behind Colorado Mountain College’s downtown Glenwood Springs offices Saturday, the view looked pretty good.To the north, the CMC geology professor explained, was a Leadville Limestone formation that was home to Glenwood Caverns on Iron Mountain.To the west, Red Mountain takes its name from the Maroon formation, itself named after the Maroon Bells near Aspen.”The Maroon Bells don’t look as red as that,” he said, comparing them to Red Mountain. “They’ve been a little bit baked,” giving them their greenish tints.Lower on Red Mountain, Zabel noted, the same Eagle Valley Evaporite formation named for the Eagle Valley can be seen. There it provides the commercial gypsum being mined and turned into wallboards.As Zabel’s audience paused to take it all in, so did he.Glenwood offers a geological diversity “almost equal to the Grand Canyon,” he said with a deeply held reverence for rock. “We don’t have to go to the Grand Canyon. It’s here.”Zabel, who has offered occasional geological tours through the Grand Canyon, quickly clarified that the well-known geological gash is still hard to surpass in its diversity and breadth of formations.But he then ushered his crowd into Glenwood’s own Glenwood Canyon, which, he would soon explain, held no lack of marvels itself.As it turned out, the two passenger vans allocated for the outing had to be supplemented by several passenger vehicles, as the turnout on this sunny spring day far surpassed expectations.Zabel’s geology walk was part of “Moving Waters: The Colorado River & the West,” a traveling exhibit now on display at the CMC Gallery at 831 Grand Ave.Locals and tourists alike took advantage of Zabel’s offer to provide an understanding of geological concepts not through a textbook, but through on-the-ground, and up-the-canyon-walls, observation.Rock hammer in hand, Zabel strode into the Horseshoe Bend section of No Name and mounted boulders to point out features such as the No Name Fault, which occurs in the area of the twin water towers above the No Name Tunnels, and runs underfoot beneath the gate blocking off the old highway. No Name is also home to Precambrian rock, from the world’s oldest geological era, which makes up 85 percent of geologic time.Dropping down to the roadside are cliff bands that are 1.7 billion years old.”This is some of the oldest rock material in Colorado,” Zabel noted.Precambrian rock is often found in canyons that have eroded down to expose it, and similarly aged rock can be found in Black Canyon of the Gunnison and the Royal Gorge.Not far away is Sawatch sandstone that’s a mere 500 million years old. In some parts of Glenwood Canyon, Zabel said, Sawatch sandstone and Precambrian rock abut each other, and you can place a finger across an unexplained break in time that spans 1.2 billion years.”We would like to read the book, and this book has 1.2 billion years of pages ripped out of it,” he said.On the ground, he ran his hand across a boulder that is marked with the burrows of some ancient animal. Further up the hillside rested cobblestones from the river, deposited perhaps 10,000 to 30,000 years ago before the Colorado carved ever deeper, Zabel said.That river at one time ran north of where the canyon lies, and at another time south. But eventually it found its present course, where it has cut away at an average of an inch or two every thousand years, and sometimes as fast as two feet over the same amount of time, as sediments and heavy flows sped up the process. Over the last 10,000 years, the river actually has been filling in the canyon, depositing more sediments than it scours away.As he stood beside the reservoir at Hanging Lake, Zabel said ancient lake deposits have been discovered in the area, suggesting a lake that might have extended all the way from Hanging Lake to Dotsero as recently as 9,000 years ago.With debate growing over whether Lake Powell should be drained, Zabel noted that there is evidence that in both Glenwood and Grand canyons, natural reservoirs have formed and drained on their own.Glenwood Canyon is probably about 3 million years old, similar to the age of the Grand Canyon, Zabel said.”We’re still putting the pieces together. If in 10 years, it’s 4 (million years), don’t blame me.”Zabel’s mix of information and a humorous, light delivery style was a hit with listeners.”He has been doing this for so long, and he doesn’t lose his enthusiasm for it,” said Glenwood resident Sharon Beattie, who has studied under Zabel on other trips.Zabel was surprised by Saturday’s turnout. The weather helped, he said, but he added, “I think living in this area has to bring out interest in knowing more about where we live.”For Zabel, there was far more to talk about than time allowed him in one morning. He noted that he will be teaching a geology class in Glenwood next fall.Even if you miss that class, Glenwood Canyon’s not going anywhere. Unless, of course, you’re counting in millions of years.
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