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23 Cards in this Set
- Front
- Back
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Glassy |
Ig rock texture. Ejected into atmosphere during eruption, cools quickly into a solid. this rapid cooling gives rock a glassy texture. |
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Porphohyritic |
Ig texture. Two different crystal sizes. Forms when molten rock containing diff crystals moves and cools the way it formed(ie, during eruption) |
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Phaneritic |
ig texture. large masses of magma that crystalize slowly, giving rock a coarse grained texture |
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Vesicular |
Ig rock. Extrusive. Contains voids that are left by gas bubbles that escape as lava solidifies |
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Pyroclastic |
Ig texture. Grouping of ash, once molten blobs, or larger blocks that were ejected during eruption |
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Aphanitic |
Ig texture. Fine grained. Cool at or just below the surface rapidly |
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Bowens reaction series |
Shows the order in which minerals crystallize from a mafic magma. Illustrates relationship btw magma and the minerals crystallizing from it during the formation of ig rocks |
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Mafic |
Basaltic Composition. Rock is composed of dark colored silicates (feldspar) |
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Felsic |
Granitic Compostion. Rock is composed of light colored silicates |
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Ash |
Less than 2mm. 1/8- 2 mm |
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Lapilli, Cinders |
2- 64mm |
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Blocks and Bombs |
more than 64 mm |
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Dust |
<1/8 mm |
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Why no vol activity in Eastern US and Canada? |
No active tectonic plates. Closest boundary is btw American and Eurasian plates (divergent), but it's much closer to Europe, nowhere near US |
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Shield Volcano |
Prouduced by pile up of fluid basaltic lavas, making "layer ccake" of lava flows. Lava pours quietly from fissures and flood surrounding land. Gas escapes easily Mauna Loa in Hawii |
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Cinder Cones Scoria Cones |
Bulit from ejected lava fragments that begin to harden in flight to produce vesicular rock.(quick process) the fragments rang from ashes to bombs. Often exist at the foot of larger vols. Vols are composed of loose fragments, not solid rock, so lava leaks from the bottom more often than it erupts from the top. Cerra Negro in Nicaragua |
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Composite Vols Strato Vols |
Buillt with gradual deposition of layers of volcanic lava and ash. Large and volient eruptions. Intermediate (andesitic) to felsic (rhyloitic) lava Common at subduction zones Mount Mayon in Phillipines |
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Chem Weathering |
Rock is chem altered into a new material weakens the surface of a rock, giving mech weathering a foothold |
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Mechanical Weathering |
Rock is broken down into smaller pieces. Mech weathering increases the surface area of a rock, providing more surface area for chem weathering to step in |
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What causes Mech weathering |
-water, frost action -root wedging -temp changes (hot OR cold) -abrasion -Mech exfoliation (unloading), pressure release...rock is shedding layers as it surfaces -Ice wedging -Human/animal activity |
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What causes Chem weathering |
-Oxidation:Oxygen in atmosphere is chem reactive, reacts w/ many metals to form oxides -dissolution:dissolving materials -hyrdolysis: breaking down minerals with h2O assistance. Atomic bonds re broken down and atoms are carried off, facilitated by more acidic H2O. the H+ ion can replace other ions in crystal lattice, often producing clay minerals |
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Explosivness of a Volcano |
Depends on vol's viscosity (more V= thicker lava=a bigger explosion) Viscosity depends on the tempature (hotter lava is less viscous) and the composition (mafic/felsic): more silica lava flows more easily (felsic is granitic, lighter in color, more silica) and more gasses (more gasses = a more volient eruption) |
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