The Physical Environment
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Chapter Review

Assess your understanding of concepts related to this chapter by answering the questions below. Click the question to reveal the correct answer.
Shield volcanoes have broad, low-angled slopes and built layer on layer of fluid lava. Composite volcanoes are steep-sided cones built from alternating flows of lava and pyroclastics. Cinder cones are smaller cones built primarily from explosive eruptions of pyroclastics.

Mauna Loa shield volcano, Hawai`i

Shield Volcano
Photograph: D. Little
Courtesy USGS

Mount Mageik volcano, Katmai National Park and Preserve, Alaksa

Composite Volcano
Photograph: R. McGimsey
Courtesy USGS

Cinder cone on Mauna Kea Volcano, Hawai`i.

Cinder Cone
Photograph: J.P. Lockwood
Courtesy USGS

In subduction zones, along the midocean ridge, and over hot spots.
Eruptions from shield volcanoes tend to be dominated by effusive eruptions of fluid lava. Composite volcanoes produces explosive eruptions from stickier magma.
Mudflows called lahars are caused by the rapid melting and runoff of snow mixing with ash and soil.
Hot ash, pumice, rock fragments and noxious gas that moves rapidly down the side of a volcano.
The most common gas released by magma is steam (H2O), followed by CO2 (carbon dioxide), SO2 (sulfur dioxide), (HCl) hydrogen chloride and other compounds.
By the volcano blowing the summit off or magma draining from the central vent removing support for the summit causing it to collapse in.

Mt. Saint Helens, Courtesy USGS
Mt. Saint Helens, Courtesy USGS

The Hawaiian islands were formed by volcanic activity over a hot spot. The youngest island in the chain lies toward the southeast as the Pacific Plate moves toward the northwest.

hot spot
Click image to enlarge
Click image to enlarge

Hawaiian islands forming
over hot spot

Source: USGS

Age of Hawaiian Islands

Source: USGS

A flood basalt of 170,000 cubic kilometers known as the Columbia River basalts covered a large portion of southeastern Washington, eastern Oregon and southern Idaho creating the plateau.
A volcanic neck is the "mold" of the central vent. Magma stuck in the central vent cools. Removal of the overlying rock exposes the plug-like shape within. Shiprock, NM (below) is a notable example of a volcanic neck.

Ship Rock, NM

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Michael Ritter (

For Citation: Ritter, Michael E. The Physical Environment: an Introduction to Physical Geography.
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