Goblin Valley’s Mushrooms

February 13, 2018

PattiW_P1040788

Photographer: Patti Weeks 
Summary Author: Patti Weeks 

However you describe them — mushrooms, gnomes, hourglasses, rock babies, Darth Vader helmets, goblins — these ghostly-looking reddish figures in the off-the-beaten-path Goblin Valley State Park in south-central Utah are the inspiration for the park’s name. Designated as a state park in 1964, the small, but intriguing 5 square mile (13 sq km) park lies in Emery County between Green River and Hanksville, several miles west of Utah Highway 24. The goblins, seen in this photo from July 23, 2014, are eroded remnants of the interbedded sandstone, siltstone and shale of the Entrada sandstone, laid down on muddy tidal flats during the Middle Jurassic Period, about 170 million years ago.

InsetGoblin Valley is at the southern end of the San Rafael Swell, a massive anticline that was uplifted about 40-70 million years ago, during the Laramide orogeny. The goblins were formed locally over the next several million years through a process called spheroidal weathering. The sharp corners of the exposed horizontal rock bed at weak vertical joints are smoothed by chemical decomposition and the physical weathering of wind and water abrasion as well as annual freeze-thaw cycles. Because the siltstone and shale layers erode faster than the more resistant interbedded sandstone layers, uneven, irregular shapes are created.

The red cliffs seen in the background are going through this same process and will gradually expand the goblin landscape over the next few million years. Note that the younger lighter-colored Curtis Formation caps the Entrada sandstone. The photo at left shows the relative size of the goblins to that of a park visitor.

Point of interest: The alien rock planet scenes in the 1999 science fiction spoof "Galaxy Quest" were filmed in Goblin Valley. Photo taken on July 23, 2014.

Photo Details: Camera: Panasonic Lumix Dmc ZS7; Focal length: 13.7 mm.; Aperture: f/5.6; Exposure: 1/640; ISO equiv. 80.