Geology1234
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- Originally created from gases released by magmas
- atmosphere
- produced by condensation of volcanic water vapor
- Hydrosphere
- both positively and negatively influenced by volcanism –Lava flows and ash weather to produce fertile soils –Violent eruptions can destroy nearly all life in their paths –Large amounts of ash and volcanic gases in atmosphere can trigger rapid cli
- Biosphere
- produced when magma reaches Earth’s surface
- lava
- Explosive eruptions can produce rapidly cooled rock fragments called
- pyroclasts –Size range from dust (ash) to boulders (blocks and volcanic bombs)
- Calm oozing of magma out of the ground produces
- lava flows
- Pyroclastics and lava flows form________igneous rocks
- extrusive
- Lava flows and pyroclasts pile up to form
- volcanoes
- appearance of a rock with respect to size, shape and arrangement of its grains
- texture
- opening through which lava erupts
- vent
- basin-like depression around the vent at the summit of the volcano
- crater
- volcanic depression much larger than the original crater, having a diameter of at least 1 km
- Caldera
- fractures through which magma rises in a volcano
- Feeder Dikes
- type of volcanoe: –Broad (base is wide in comparison to height) –Gently sloping –Composed of solidified lava flows –Flows often contain lava tubes –Most common in ocean basins
- Shield volcanoes
- type of volcanoe: –Small –Steeply sloping –Composed of a pile of loose cinders
- Cinder cones
- type of volcanoe: –AKA stratovolcanoes –Moderately to steeply sloping –Constructed of alternating layers of pyroclastic debris and solidified lava flows –Composed primarily of intermediate composition volcanic rocks (i.e., andesite) –Most c
- Composite volcanoes
- eruption type: –Very fluid (basalts) –Extremely large in volume –Create extensive lava plateaus –Eruption times correspond with largest mass extinction events
- flood eruption
- eruption type: –Nearly always basaltic –Mid-ocean ridge eruptions –Pillow basalts
- submarine eruption
- A change in the composition of a magma body is known as
- magma evolution
- Magma evolution can occur by ___, ___, ___, or ___.
- differentiation, partial melting, assimilation, or magma mixing
- ______ involves the changing of magma composition by the removal of denser early-formed ferromagnesian minerals by crystal settling
- Differentiation
- _______ produces magmas less mafic than their source rocks, because lower melting point minerals are more felsic in composition
- Partial melting
- _____ occurs when a hot magma melts and incorporates more felsic surrounding country rock
- Assimilation