Sunday, October 12, 2014

Walking the Devil’s Backbone

Driving home from Rocky Mountain National Park we stopped just a few miles west of Loveland, Colorado, to examine the Devil’s Backbone.  How could we not?!  It’s an eye-catching landform and there’s a trailhead at the south end, right off Highway 34.

Demonic geologic features are common in Colorado -- there are at least twenty-one (Colorado Geological Society 2009).  Curiously, all are composed of either igneous rock or Mesozoic sandstone (Mesozoic means 252-66 million years old).  Some early geologists assumed the Devil's Backbone was igneous, a dike.  It has that look -- long, linear and narrow.  But then someone investigated and found it’s Mesozoic sandstone, specifically the Dakota sandstone -- sediments deposited by rivers flowing into an interior seaway to the east roughly 100 million years ago.
Here the Dakota is a mix of fine and coarse river deposits.  Note nearly vertical orientation of beds.
Along the Front Range of the Rocky Mountains, the Dakota forms hogbacks -- ridges of steeply-tilted sedimentary strata.  In the Devil’s Backbone the sandstone is really steep, basically vertical.  It's part of the west flank of a small anticline (uplift) east of the main Rocky Mountain uplift.  The more gentle east flank of the anticline is visible from the trail.  In the next photo, it's marked by rimrock with trees on the horizon, above boulder-strewn slopes.  The Triassic red Chugwater Formation is exposed in the valley below.  The valley also contains the “crest” of the breached anticline (cut through by erosion.)
Looking from the Backbone toward the hogback on the east flank of the anticline. 
The Wild Loop trail along the Devil’s Backbone is about two miles roundtrip, and is an easy stroll.  A short spur leads to the “Keyhole” where you can stand among the Devil’s vertebrae!
A demonic vertebra.
The Keyhole.
Long's Peak (Rocky Mt NP) from inside the Keyhole; Dave's finger rests on summit (click on image to view).
For more information, download the trail brochure provided by Larimer County’s Parks and Open Spaces.  This is the southern end of a network of trails extending north along the Front Range to Fort Collins.  Consider a weekday visit.  It’s popular, and the parking lot often fills on weekends.

NOTE:  The Devil has multiple backbones -- at least eight in the USA.

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