Dotsero Volcanic Center
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Dotsero Crater, near the Dotsero railroad junction in central Colorado, is one of several volcanic features resulting from basaltic eruptions between 3,800 and 5,500 years ago (4,150 +/- 300 years B.P. radiocarbon age).
Location: Colorado, Eagle County
Latitude: 39.663° N
Longitude: 107.032° W
Elevation: 2,230 (m) 7,316 (f)
Volcano type: scoria cone, lava flow
Most recent eruption: 4,150 years ago
Nearby towns: Dotsero, Gypsum, Eagle, Glenwood Springs
Threat Potential: Moderate*
The earliest eruptions occurred along a north-northeast trend and built scoria cones that ascend the north canyon wall of the Eagle River near where it joins the Colorado River. An ‘a‘ā lava flow issued southward from a gulch and buried about 0.7 km2 (168 acres) of the adjacent floodplain. Today, U.S. Interstate Highway 70 cuts this lava flow. Dotsero Crater formed when magma encountered water and explosively blasted a crater through the country rock, destroying part of the scoria-cone chain and showering tephra across the landscape. This tephra fallout includes a substantial amount of red sandstone bedrock fragments. Although 20 m (65 ft) or thicker around the vent, much of the tephra was blown eastward from the crater by prevailing winds. The crater today has a diameter of about 750 m (2,460 ft) and a depth of 76 m (250 ft) at low rim points. When first formed, the crater was possibly as deep as 400 m (about 1,300 ft), but has since been partly filled.