EARTH SCIENCE
VOLCANOES
|
Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
|
|
|
is built from layers of lava and volcanic ash.
|
|
|
consists primarily of cinders and volcanic rock.
|
|
|
composed almost entirely of thin lava.
|
|
|
None of the above
|
Detailed explanation-1: -Composite volcanoes are built up by successive eruptions of domes, lava flows and pyroclastic flows, but also can experience large blasts that destroy large areas of their summits, such as the May 1980 explosion and landslide at Mount St. Helens. Landslides may occur during eruptions or at other times.
Detailed explanation-2: -A cross section of a composite volcano reveals alternating layers of rock and ash: (1) magma chamber, (2) bedrock, (3) pipe, (4) ash layers, (5) lava layers, (6) lava flow, (7) vent, (8) lava, (9) ash cloud. Frequently there is a large crater at the top from the last eruption.
Detailed explanation-3: -Composite volcanoes are tall, symetrically shaped, with steep sides, sometimes rising 10, 000 feet high. They are built of alternating layers of lava flows, volcanic ash, and cinders.
Detailed explanation-4: -Stratovolcano: A large, steep-sided, symmetrical cone built of alternating layers (strata) of lava, ash, cinders, blocks, and bombs. Also called composite volcano, these stratovolcanoes form some of Earth’s grandest mountains rising as much as 8, 000 feet above their bases (movie).
Detailed explanation-5: -Stratovolcanoes, also called composite volcanoes, are typically steep-sided, symmetrical cones built of alternating layers of lava flows, volcanic ash, and other eruptive products (see animation courtesy of Exploring the Environment).