Tag Archive for: geosight

GeoSight Devils Playground

Do you think playgrounds are boring? Are you getting sick of the same old swing and slide? Well check out this playground—it rocks!

Devils Playground is not your typical playground at the park, but a playground of granitic rock weathered into fantastic forms and eerie shapes. Located on Bureau of Land Management and state land, Devils Playground is a relatively unknown geologic curiosity found in a remote region of northwestern Utah.

Devils Playground consists of Tertiary-age (approximately 38 million years old) granitic rock formed from a cooling magma body that intruded overlying Paleozoic (400 to 300 million years old) sedimentary rocks. Known as the Emigrant Pass pluton, this intrusion covers an area of approximately 10 square miles in the southern part of the Grouse Creek Mountains.

Check out more on Devil’s Playground HERE.

Take a tour of our other GeoSights HERE.

geosights-wall-arch-beforeDuring the night of August 4, 2008, Utah lost a popular giant when Wall Arch, a prominent arch along the Devils Garden Trail in Arches National Park, collapsed.

While not the largest or most famous arch in the park, Wall Arch was still a favorite due to its proximity to Landscape Arch along the always-busy trail. With a measured span of 55 feet, it was ranked as 12th largest in the park (some publications and Web sites give the span as 71 feet – this is actually the “breadth”, a dimension that is not useful for comparing arches).

While no arch lasts forever, it is still extremely rare to see such a dramatic example of “geology in action.” We do not have a good geologic tool for dating arch formation, but we are sure that Wall Arch had stood nearly unchanged for hundreds, and probably thousands of years.



geosights-fanatsy-canyonGeologic Information: The sandstone layer in which the pinnacles, pillars, arches, and knobs of Fantasy Canyon are formed consists of ancient river channel sediments. The underlying and overlying rock layers sandwiching the sandstone layer, and creating scenic badland topography around the canyon, are finer grained floodplain deposits.

During the Eocene Epoch, 55 to 34 million years ago, the Fantasy Canyon area was at the fringe of a vast subtropical lake – Lake Uinta – that at peak level stretched from the Wasatch Plateau to western Colorado. The lake was in a drying phase and retreating westward by the end of the Eocene.



cascade-springsGeologic Information: The area around Cascade Springs is underlain by coarse-grained glacial sediment deposited when glaciers covered high elevations of the Wasatch Range approximately 30,000 to 10,000 years ago.

Beneath the glacial deposits, bedrock consists of Cambrian-age (about 500 million years old) quartzite, shale, sandstone, and limestone. These rocks were transported eastward 30 to 50 miles during low-angle faulting on the Charleston-Nebo thrust fault around 80 million years ago. As a result of the faulting, the bedrock in the vicinity of the springs is tilted and highly fractured.