Geology Reference
In-Depth Information
Geo-inSight
Types of Volcanoes
All volcanoes are structures resulting from the eruption
of lava and pyroclastic materials, but they are all unique
in their history of eruptions and development. Never-
theless, most are conveniently classified as one of the
types shown here: shield, cinder cone, composite, and
lava dome. There are also places where eruptions of
very fluid lava take place along fissures and volcanoes
do not develop.
Flank eruption
Summit caldera
Central vent
Magma
chamber
1. Shield volcanoes consist of numerous thin basalt lava
flows that build up mountains with slopes rarely
exceeding 10 degrees.
2. Sierra Grande is an extinct shield volcano in the
Raton-Clayton volcanic field of northeastern New Mexico.
It stands about 670 m above the surround plain and it is
15 km in diameter. This 2.6- to 4.0-million-year-old shield
volcano is unusual in that it is made up of andesite rather
than basalt lava flows.
3. View of Mauna Loa, an active shield volcano on Hawaii,
with its upper 1.5 km covered by snow. Mauna Loa is the
largest mountain on Earth; it measures about 100 km
across its base, stands more than 9.5 km above the
seafloor, and is made up of an estimated 50,000 km 3 of
material.
4. A cinder cone in the Big Pine volcanic field near Big Pine,
California. Notice the large crater and the eroded cinder
cone in the right foreground. The Sierra Nevada is in the
background.
5. Cinder cones in the Cima volcanic field in the
Mojave Desert of southeastern California. Volcanic
activity from 7.6 million to 10,000 years ago
produced 40 cinder cones and numerous basalt
lava flows.
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