07/19/2020
Coke Ovens, Colorado National Monument.
John Otto supposedly called them the “Haystacks,” but they have been known since the building of Rim Rock Drive as the Coke Ovens, so named for their resemblance to the brick kilns called coke ovens used to produce coke for the manufacturing of steel.*
Like most of the named features at Colorado National Monument, these domes are formed from the erosion of the buff-colored Wingate Sandstone that composes most of the cliffs in the Monument. Laid down in the Lower Jurassic period, the 350-feet-thick Wingate Sandstone at the Monument is softer than the 45-80-feet-thick Kayenta sandstone that capped it. The Kayenta capstone protects the Wingate underneath it like a hat, and reduces the speed at which it erodes. But the Kayenta over the ages eventually crumbles away, breaking off at the rims as the surviving Wingate succumbs to gravity, and the formations composed from it narrow until the edges of the capstone slowly snap off under their unsupported weight.
After millions of years, the Kayenta will erode away, leaving the now-unprotected Wingate underneath. Because it is softer, what had been rugged monoliths like Independence Monument while they were protected by the Kayenta capstones will erode away into the soft-shouldered giants we see today.
The last remnants of the Kayenta capstones are easily discerned in this undated photograph taken by Grand Junction’s most well-known historical photographer, Frank Dean (1864–1947). The capstones might look crumbly, but the Earth will likely make its way a few million times around Sol before they’re completely gone.
*A coke oven is used burn impurities and moisture out of coal so the resulting purified coal, called coke, can be used in the production of steel. Coal is loaded inside the charcoal-burning ovens, made of fire bricks, also known as kiln bricks, and then sealed in, with only small vents left open to allow the minimum amount of oxygen in to support combustion. Temperatures inside the ovens, in which the coal is heated, can reach 2400 degrees Fahrenheit, so fire bricks, and the mortar that joins them, have to be made especially dense and have a high silicon content to withstand such temperatures.
Steve & Denise Hight
Fruita Historic Preservation Board
Historical Photos of Fruita & Western Colorado:
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Historical Photos of Women’s Suffrage:
https://www.facebook.com/HistoricalSuffragePhotos/