Basin & Range: Volcanoes


Why is there such a variety of lavas in the Basin & Range province?

Simplified deformation and volcanism in an extensional regime that characterizes a basin and range province. Shows the basic processes that lead to eruptions in the region, and what type of eruptions occur. Includes lava flows, ash flow, dome building and cinder cones. During Basin & Range extension, the plates pull apart, the mantle rises and melts due to lower pressures near the surface. The style of eruption depends on how long the magma sits in the crust and undergoes processes such as crystallization and melting and assimilation of wall rock.

CLOSED CAPTIONING: .srt file is included with the download. Use an appropriate media player to utilize captioning.


Thinned extended crust yields these eruptions:

  • Basalt magma erupts as thin lava flows
  • Basalt magma at depth melts the crust and makes gas-rich high-silica melt
  • Low-gas rhyolite forms lava domes
  • Gas-rich basalt forms cinder cones.

Related Interactives

Interactive map reveals seismology, geology, and geologic history of the midwest.

(IRIS is going to discontinue Flash animations in 2020)

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Long Valley Caldera area has had a history of eruptions and earthquake swarms.  Learn more with this interactive map that reveals geology, eruptions, earthquakes, and more.

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This interactive map of the Basin and Range Province reveals earthquakes, faults, hazards, volcanoes, mines, and National Parks.

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This interactive map of the Basin-Range Province reveals information about the youngest volcanic features associated with the region.

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Related Animations

Over most of the last 30 million years, movement of hot mantle beneath the region caused the surface to dome up and then partially collapse under its own weight, as it pulled apart. Currently, there is very little actual stretching going on, and the small amount is concentrated on the Western and Eastern edges of the Basin and Range.

Animation Novice

Cross section of the shallow crust in the Basin & Range. Earthquake produces seismic waves that bump an array of seismic stations. One station records the arrival of the seismic waves on a seismogram. 

Animation Novice

As extension and uplift occur, erosion and sedimentation happen simultaneously but at slower rates. As extension slows down, erosion and sedimentation can overcome mountain building.


Animation Novice

Related Videos

How can I demonstrate plate tectonic principles in the classroom?

Video lecture demonstrates the use of foam faults to demonstrate faults, and a deck of cards to demonstrate folds and fabrics in rock layers. Different types of faults include: normal (extensional) faults; reverse or thrust (compressional) faults; and strike-slip (shearing) faults.

Video Novice