A Geological Tour of Denver, Golden, and Colorado's Front Range

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Geologic Time Period

The Lyons Sandstone

North Gateway Rock - Lyons sandstone in Garden of the Gods Park

North Gateway Rock - Lyons sandstone in Garden of the Gods Park, Colorado Springs.

By Jack Barkstrom

Sand as far as the eye can see...

The Permian Period brought a drier climate to Colorado. Most of the streams which deposited the sands of the Fountain Formation gradually dried up and the surrounding area turned to desert. Sand still was carried by streams, when seasonal rains filled them. When they dried up, winds picked up the sand and deposited it in large dunes. Modern counterparts can be seen in the Great Sand Dunes National Monument, west of Walsenburg, Colorado and at White Sands National Monument, southwest of Alamogordo, New Mexico. (The dunes of the Colorado's Great Sand Dunes are not remnants of the Permian Period, but are nevertheless believed to be quite old, probably forming in the Pleistocene Epoch, which began 1.8 million years ago.  White Sands formed within the last 25,000 years.)  Animal and plant life did not disappear, but it was forced to adapt. Some animals managed to live on or near the dunes. Others found areas outside the dunes more hospitable.  Forests existed in the region south and east of the dunes.[1]

Near the town of Lyons, Colorado, north of Boulder, modern industry created quarries to mine the sandstone for flagstone used in sidewalks and terraces in Denver and other cities along the Front Range.  Some of the Lyons Sandstone found along the Front Range is a mix of white, red, grey, and pink, the result of the removal of iron as the sand was re-worked.[2]

The desert climate which created the dunes existed for some ten to fifteen million years. Erosion continued to supply the sand, but water once again moved in to cover the flat landscape.

(1) Halka Chronic and Felicie Williams, "Roadside Geology of Colorado, 2nd ed.," Mountain Press Publishing Company, (Missoula, MT 2005), p. 185;
Kirk R. Johnson and Robert G. Raynolds, "Ancient Denvers: Scenes from the Past 300 Million Years of the Colorado Front Range," Denver Museum of Nature & Science, (Denver 2003), p. 8;
Laurence Parent, "Scenic Driving: New Mexico, 2nd ed.," Falcon, (Helena, Montana 2005), p. 115.
(2) Andrew M. Taylor, Ph.D., "Guide to the Geology of Colorado," Cataract Lode Mining Company, (Golden, CO 1999), p. 59;
Chronic and Williams, "Roadside Geology of Colorado," p. 26.