Chapter 13 Flashcards
a volcanically active area of Earth’s surface, commonly far from a tectonic plate boundary.
Hot spot
Oceanic volcanoes that commonly form from mafic magma, which has a low viscosity the gases can easily escape .
Quiet Eruption
liquid rock produced under Earth’s surface.
Magma
Rock that forms when magma cools .
Igneous Rock
are continental volcanoes and have felsic lava which also contains large amounts of trapped gases.
Explosive eruption
fragments of rock that form during a volcanic eruption.
Pyroclastic Material
magma that flows onto Earth’s surface; the rock that forms when lava cools and solidifies.
Lava
Large pyroclastic particles that are less than 64 mm in diameter.
Lapilli
large formations of igneous rock.
Pluton
forms when magma cools quickly from an underwater volcano.
Pillow lava
describes magma or igneous rock that is rich in feldspar and silica and that is generally light in color.
Felsic magma
describes magma or igneous rock that is rich in magnesium and iron and that is generally dark in color.
Mafic magma
Volcanic ash that is less than 0.25 mm in diameter.
Volcanic dust
If the lava continues to flow after the crust forms, the crust wrinkles to form a volcanic rock.
Pahoehoe
large, circular depression that forms when the magma chamber below a volcano partially empties and causes the ground above to sink
Caldera
Under what conditions does rock melt?
If the temp rises above melting point,if pressure is removed from rock, and if fluids are added.
What are the major volcanic areas ?
Subduction zones, mid-ocean ridges and hotspots.
What are the signals of a volcanic eruption?
Changes in earthquake activity, bulges on the side of the volcano, and a change in the amount of composition of volcanic gases.
What type of eruption was Mt. St. Helens ?
Explosive
How was Iceland formed ?
When an island was cut into two parts by a fissure
Explain how igneous rock forms .
When magma cools.
How do most island volcanoes, such as those in Hawaii, form?
From Mafic magma in the the oceanic volcanoes.
List the five major types of pyroclastic material, in order of size,from smallest to largest.
Volcanic ash, volcanic dust, lapilli, volcanic bombs, volcanic blocks.
any activity that includes the movement of magma toward or onto Earth’s surface.
Volcanism
