Castle Rock in Douglas County, Colorado — The American Mountains (Southwest)
The Rock
Gray Gold
Photographed by Charles T. Harrell, July 3, 2011
1. The Rock Marker
Inscription.
The Rock. Gray Gold. A geologic phenomenon known as a “glowing avalanche” formed Castle Rock and the other buttes of Douglas County 36.7 million years ago. A volcanic eruption near Mount Princeton, about 95 miles southwest of here, spewed a frothy, gleaming cloud of lava across the landscape. As soon as the liquid rock hit the ground it hardened into a glassy-textured layer some 15 to 30 feet thick, known today as Castle Rock rhyolite. Throughout time, powerful wind and water forces scoured this valley and eroded the lava flow, leaving behind the rack-capped mesas seen today from Sedalia to Greenland on either side of East Plum Creek. These remnants supported a major industry in Douglas County-rock quarrying-from the 1870s onward., Gray Gold , In 1872 Silas Madge pried loose some of the gray, buff, and pink rocks from a prominent mesa on his ranch and sent them to mineral experts in Denver. The stone proved to be a superlative building material-weather resistant, exceptionally strong for its weight, and easily cut. Madge capitalized on the discovery with a profitable but backbreaking quarry just south of Castle Rock. When two other quarries opened nearby, the town and county profited from the industry. Builders used the rock for prominent commercial and residential buildings in Denver, Colorado Springs, and Pueblo, and as far away was Kansas City, Cheyenne, and Omaha. Closer to home, rhyolite graced the old Douglas County Courthouse, railroad depots, schools, churches, businesses, and houses throughout the county. In the first decade of the 1900s, concrete surpassed stone as the preferred building material in the region and the heyday for the quarries ended, although the rock is still quarried for road and construction projects., Captions: , The Rockies Explode by Jan Vrieson. An artist’s rendering of a cloud of superheated ash spewing toward Castle Rock from a distant, prehistoric volcanic eruption. All rights reserved, Image Archive, Denver Museum of Nature and Science. In the early decades of the twentieth century, motorists enjoyed touring Perry park Ranch to view the dramatic hogback formations. , Photo courtesy Denver Public Library. , Colorado Historical Society
A geologic phenomenon known as a “glowing avalanche” formed Castle Rock and the other buttes of Douglas County 36.7 million years ago. A volcanic eruption near Mount Princeton, about 95 miles southwest of here, spewed a frothy, gleaming cloud of lava across the landscape. As soon as the liquid rock hit the ground it hardened into a glassy-textured layer some 15 to 30 feet thick, known today as Castle Rock rhyolite. Throughout time, powerful wind and water forces scoured this valley and eroded the lava flow, leaving behind the rack-capped mesas seen today from Sedalia to Greenland on either side of East Plum Creek. These remnants supported a major industry in Douglas County-rock quarrying-from the 1870s onward.
Gray Gold
In 1872 Silas Madge pried loose some of the gray, buff, and pink rocks from a prominent mesa on his ranch and sent them to mineral experts in Denver. The stone proved to be a superlative building material-weather resistant, exceptionally strong for its weight, and easily cut. Madge capitalized on the discovery with a profitable but backbreaking quarry just south of Castle Rock. When two other quarries opened nearby, the town and county profited from the industry. Builders used the rock for prominent commercial and residential buildings in Denver, Colorado Springs, and Pueblo, and as far away was Kansas
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City, Cheyenne, and Omaha. Closer to home, rhyolite graced the old Douglas County Courthouse, railroad depots, schools, churches, businesses, and houses throughout the county. In the first decade of the 1900s, concrete surpassed stone as the preferred building material in the region and the heyday for the quarries ended, although the rock is still quarried for road and construction projects.
Captions:
The Rockies Explode by Jan Vrieson. An artist’s rendering of a cloud of superheated ash spewing toward Castle Rock from a distant, prehistoric volcanic eruption. All rights reserved, Image Archive, Denver Museum of Nature and Science.
In the early decades of the twentieth century, motorists enjoyed touring Perry park Ranch to view the dramatic hogback formations. Photo courtesy Denver Public Library.
Colorado Historical Society
Topics. This historical marker is listed in these topic lists: Industry & Commerce • Natural Features. A significant historical year for this entry is 1872.
Location. 39° 22.347′ N, 104° 51.611′ W. Marker is in Castle Rock, Colorado, in Douglas County. It is on Wilcox Street close to 3rd Street, on the right when traveling south. Touch for map. Marker is in this post office area: Castle Rock CO 80104, United States of America. Touch for directions.
Regionally, this marker is in Colorado’s Front Range. It is also in the American Mountain West. Globally, it is in North America, the Rocky Mountains, the Western Hemisphere, the Western World, and the Anglosphere. Historically, it finds itself in what was once the Louisiana Purchase.
Other nearby markers. At least 8 other markers are within 6 miles of this marker, measured as the crow flies: Good Roads in Colorado (here, next to this marker); Keystone Hotel
Photographed by Mark Hilton, July 1, 2017
2. View of marker looking northwest towards Douglas County Government buildings.
Other markers no longer nearby. Douglas (was about 300 feet away, measured in a direct line but has been confirmed missing); Castle Rock (was about 300 feet away but has been confirmed missing).
Photographed by Mark Hilton, July 1, 2017
3. View from marker of intersection of Wilcox and Third Streets.
Credits. This page was last revised on December 23, 2024. It was originally submitted on August 15, 2011, by Charles T. Harrell of Woodford, Virginia. This page has been viewed 1,711 times since then and 56 times this year. Photos:1. submitted on August 15, 2011, by Charles T. Harrell of Woodford, Virginia. 2, 3. submitted on July 1, 2017, by Mark Hilton of Montgomery, Alabama. • Bill Pfingsten was the editor who published this page.
