The Dakota Wall
The Dakota Wall, a sandstone formation nicknamed the “Backbone of the Rockies,” was formed when fault lines were broken and turned upright. These great sandstone walls stretch all along the Front Range of the Rockies and are visible in Spanish Peaks Country when traveling through the Cucharas River Valley, over La Veta Pass, and into northern Huerfano County. In many places along this journey, you can see where the ground was actually folded and broken by the pressures along the fault line.
About 30 million years ago, the process that built the modern Rockies about 50 miles east of the Ancestral Rockies began. This process saw the creation of the Sangre de Cristos. The Sangres are fault block mountains – there are faults along both the east and west side of the mountains and the mountains themselves were raised up in one big chunk of rock. Along the fault line on the east side of the mountains, the Dakota formation again was broken and turned upright.
The Wet Mountain Valley is a fault block valley in that there are faults along the east and west sides of the valley, and the valley floor dropped when the Sangres rose. There are sections of the Dakota Wall visible above ground along the east side of the valley, in the western foothills of the Wet Mountains. The major mass of the Wet Mountains themselves was put in place during the Colorado Orogeny (some 1.7-1.8 billion years ago), about the same time as the Mt. Blanca Massif and the Front Range around Pike’s Peak came into existence.
Other places where the Dakota Wall sticks out above ground are the Flatirons near Boulder, Garden of the Gods near Colorado Springs, and the Stonewall near Cerrillos, New Mexico.