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New MexicoExample

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Drawing/Section

Cat Hills, Los Lunas

McCartys lava flow, El Malpais

Cerro La Jara, Valles Caldera, Jemez Mtns

Mount Taylor volcano

Zuni Salt Lake crater

Cabezon Peak, Rio Puercovolcanic neck

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VolcanoType

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Raton-Clayton volcanic field

Valles Caldera

Cerro Verde volcano

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How and Why It Erupts

Poster design, graphic, and photographs by L.S. Crumpler and Jayne Aubele. These are just a few of New Mexico’s volcanoes.For more information about the location of volcanoes in New Mexico go to poster no. 2, or go to “Volcanoes of New Mexico” at

www.nmnaturalhistory.org/sci_volcanoes.html

New Mexico Museum of Natural History and ScienceImagenés de la historia natural, No. 3

• violent explosive and catastrophic eruption of glowing clouds of ash that flow awayfrom the caldera (ash-flows or pyroclastic flows), due to very high gas content and veryhigh silica magma in a very large magma chamber

• the roof of the extremely large, shallow magma chamber collapses during and aftereruption

• uplift (rebound) of the caldera floor over a long period of time to form Redondo Peak,and even later eruptions of high silica, low gas content lava domes around the interiormargin of the caldera

• lava intrudes earlier lava and piles up at the vent because very high silica magmamakes the lava viscous

• mostly non-explosive eruptions due to low gas content magma

• near-surface intrusions are formed when continued eruptions push into the pile

• many intermittent eruptions of different types over a long time period caused bychanges in the magma composition

• built by lava flows, ash, and domes from multiple conduits of intermediate to lowviscosity due to medium to low silica and gas content magma

• intermittent mudflows and landslides are interlayered with ash, lava flows. and brokenrocks due to crumbly materials erupted on steep upper slopes

• single to multiple eruptions that extend over years to decades

• moderately explosive eruptions of mafic (basaltic) composition, including lava flows,due to moderate gas content and low silica magma

• builds a small volcano of ash, cinder, and scoria (fragmented magma) that iscommonly 0.6 to 1.2 miles (1-2 km) in diameter

• multiple eruptions of long lava flows from a central conduit over a moderately longtime period

• mostly non-explosive and fluid eruptions, due to low silica and low gas content magma

• forms a low, broad volcano with some ash and cinder at the summit

• single eruption of a long, fluid, large volume of mafic (basaltic) lava

• mainly lava with little ash and cinder due to low gas

• lava covers large area due to low viscosity and low silica magma

• usually erupted in association with a small cinder cone source volcano

• multiple violent steam-blast eruptions, due to the interaction of magma andgroundwater or surface water

• forms a crater with its floor below ground level that is surrounded by a low rim of ejectacomposed of fragmented magma and surrounding rock

• the near-surface interior of a small volcano that has experienced erosion of its exteriorflanks

• erosion leaves behind the hard crater fill (lava flows, ash, and cinder) and thenear-surface, magma-filled throat or conduit of the original volcano

• a large region over which volcanism is active over a time period from thousands tomillions of years

• many new eruptions from multiple conduits, rather than many eruptions from a singlevolcanic vent, due to small batches of magma that are generated and erupted fromdifferent places within the region over time to form each individual volcano

• consists of a concentration of varied types of small volcanoes, dominantly cindercones and their associated lava flows, but also some shield volcanoes and lava domes

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