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  • Country
  • Volcanic Region
  • Primary Volcano Type
  • Last Known Eruption
  • 39.661°N
  • 107.035°W

  • 2230 m
    7314 ft

  • 328010
  • Latitude
  • Longitude

  • Summit

  • Volcano

The Global Volcanism Program has no activity reports for Dotsero.

The Global Volcanism Program has no Weekly Reports available for Dotsero.

The Global Volcanism Program has no Bulletin Reports available for Dotsero.

Volcano Types

Pyroclastic cone(s)

Tectonic Setting

Rift zone
Continental crust (> 25 km)

Rock Types

Basalt / Picro-Basalt


Within 5 km
Within 10 km
Within 30 km
Within 100 km

Geological Summary

A small maar and scoria cone complex at Dotsero, near the junction of the Colorado and Eagle Rivers west of the Gore Range, is the only Holocene volcano in Colorado. Although Interstate highway 70 cuts across a lava flow from Dotsero, this volcanic center is one of the least known in the western United States. The most prominent feature of the Dotsero complex is a 700 m wide and 400 m deep maar that was erupted about 4150 radiocarbon years ago along a ridge consisting of evaporites and reddish oxidized sandstones of Pennsylvanian age. Small scoria cones were constructed along a NNE-SSW line on either side of the maar. Small lahars preceded eruption of a basaltic lava flow that traveled 3 km down two narrow V-shaped valleys and spread out onto the floodplain of the Eagle River, diverting the river to the south side of the valley. Older Pleistocene basaltic lava flows occur nearby at Willow Peak, McCoy, and Triangle Peak.

Eruptive History

Summary of Holocene eruption dates and Volcanic Explosivity Indices (VEI).

Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
2200 BCE ± 300 years Unknown Confirmed 2 Radiocarbon (uncorrected)

The Global Volcanism Program has no synonyms or subfeatures listed for Dotsero.

Photo Gallery

During the mid-Holocene a maar was formed in central Colorado near the junction of the Colorado and Eagle Rivers west of the Gore Range. The quarry in the foreground is cut into basaltic tephra deposits on the rim of the maar. The 700 m wide maar is 400 m deep and cuts a ridge of evaporites and reddish oxidized sandstones of Pennsylvanian age, which can be seen on the far crater wall. The maar was erupted about 4150 radiocarbon years ago and is the youngest volcanic feature of Colorado. The Eagle River lies to the south in the valley beyond the crater.

Photo by Lee Siebert, 1999 (Smithsonian Institution).


The following references have all been used during the compilation of data for this volcano, it is not a comprehensive bibliography. Discussion of another volcano or eruption (sometimes far from the one that is the subject of the manuscript) may produce a citation that is not at all apparent from the title.

Bass N W, Northrop S A, 1963. Geology of Glenwood Springs quadrangle and vicinty, northwestern Colorado. U S Geol Surv Bull, 1142-J: 1-74.

Larson E E, Ozima M, Bradley W C, 1975. Late Cenozoic basic volcanism in northwestern Colorado and its implications concerning tectonism and the origin of the Colorado River system. Geol Soc Amer Mem, 144: 115-178.

Leat P T, Thompson R N, Dickin A P, Morrison M A, Hendry G L, 1989. Quaternary volcanism in northwestern Colorado: implications for the roles of asthenosphere and lithosphere in the genesis of continental basalts. J Volc Geotherm Res, 37: 291-310.

Smith R L, Shaw H R, 1975. Igneous-related geothermal systems. U S Geol Surv Circ, 726: 58-83.

Affiliated Databases

Large Eruptions of Dotsero Information about large Quaternary eruptions (VEI >= 4) is cataloged in the Large Magnitude Explosive Volcanic Eruptions (LaMEVE) database of the Volcano Global Risk Identification and Analysis Project (VOGRIPA).
WOVOdat WOVOdat is a database of volcanic unrest; instrumentally and visually recorded changes in seismicity, ground deformation, gas emission, and other parameters from their normal baselines. It is sponsored by the World Organization of Volcano Observatories (WOVO) and presently hosted at the Earth Observatory of Singapore.
EarthChem EarthChem develops and maintains databases, software, and services that support the preservation, discovery, access and analysis of geochemical data, and facilitate their integration with the broad array of other available earth science parameters. EarthChem is operated by a joint team of disciplinary scientists, data scientists, data managers and information technology developers who are part of the NSF-funded data facility Integrated Earth Data Applications (IEDA). IEDA is a collaborative effort of EarthChem and the Marine Geoscience Data System (MGDS).
Smithsonian Collections Search the Smithsonian's NMNH Department of Mineral Sciences collections database. Go to the "Search Rocks and Ores" tab and use the Volcano Name drop-down to find samples.