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30 Cards in this Set
- Front
- Back
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What is the definition of a volcano?
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It forms at the end of a central vent or conduit that rises from the asthenosphere through the crust into a volcanic mountain.
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What is a crater?
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It is a circular surface depression that usually forms at the summit.
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What is lava?
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It is molten rock, gasses, and pyroclastics, or tephra that pass through the vent to the surface and build a volcanic landform.
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What is tephra?
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Pulverized rock and clastic materials of various sizes ejected violently during the eruption.
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Lava- What is Aa? Why is the texture the way that it is?
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It is basaltic lava that is rough and jagged with sharp edges. This texture happens because the lava loses trapped gasses, flowing slowly, and develops a thick skin that cracks into the jagged surface
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Lava- What is Pahoehoe?
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As this lava flows it forms a thick crust that develops, folds, and appears "ropy", like coiled, twisted rope.
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What are the three different areas that volcanic activity can occur? Name an example of each one.
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1. Along subduction boundaries at continental plate-oceanic plate convergence (such as Mt. St. Helens), or oceanic plate-oceanic plate convergence (Phillipines and Japan).
2. Along sea floor spreading centers on the ocean floor (Iceland on the Mid-Atlantic Ridge or off the coast of Oregon and Washington) and areas of rifting on continental plates (the rift zone in East Africa). 3. At hot spots, where individual plumes of magma rise to the crust (such as Hawaii and Yellowstone National Park). |
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What are effusive eruptions?
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These are relatively gentle eruptions that produce enormous volumes of lava annually on the seafloor and in places such as Iceland and Hawaii. Direct eruptions from the asthenosphere produce a low-viscosity magma that is very fluid and cools to form dark, basaltic rock (less than 50% silica and rich in iron and magnesium). Gasses readily escape from the magma because of it's texture causing it to pour on the surface, with relatively small explosions and little tephra. However, dramatic fountains of basaltic lava sometimes shoot upward, powered by jets of rapidly expanding gasses.
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Explosive Eruptions
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Volcanic activity along subduction zones produces the well-known explosive volcanos. Magma produced by melting of subducted oceanic plate and other materials is thicker than magma from effusive volcanos. It is 50-75% silica and high in aluminum; consequently, it tends to block the magma conduit inside the volcanos, trapping and compressing gasses, causing pressure conditions to build for possible eruption. This type of magma forms a lighter rock at the surface.
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What is another name for an explosive volcano?
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Composite
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What is the definition of weathering?
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It encompasses a group of processes by which surface and subsurface rock disentegrates into mineral particles or dissolves in water.
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Physical weathering
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Also known as mechanical weathering. This is when rock is broken and disentigrated without any chemical altercation.
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Name the types of physical weathering...
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1. Freeze-thaw action
2. Crystallization 3. Pressure-Release Jointing |
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What is freeze-thaw action?
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Repeated cycles of water freezing and thawing break rock segments apart.
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What is crystallizartion?
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In dry climates, dry weather draws moisture to the surface of the rocks. As water evaporates, crystals form from the dissolved minerals. As this process continues over time and the crystals grow and enlarge, the exert a force great enough to spread apart individual mineral grains and begin breaking up the rock.
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What is pressure-release jointing?
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Layer after layer of rock peels off in curved slabs or plates, thinner at the top of the rock structure and thicker at the sides.
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What is sheeting?
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The slip off process of the pressure-release jointing.
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What is the exfoliation dome?
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An arch-shaped and dome-shaped feature on the exposed landscape.
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What is chemical weathering?
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This refers to the actual decomposistion and decay of the constituent minerals in rock due to chemical altercation of those minerals always in the presence of water.
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What is spheroidal weathering?
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Is a chemical process that occurs when water penetrates joints and fractures in rock and dissolves the rock's cementing materials.
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What are the types of chemical weathering?
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Hydration
Hydrolysis Oxidation Carbonation and Solution |
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What is hydration?
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Meaning "combination of water", involves little chemical change. Water becomes part of the chemical composition of the mineral. When some minerals hydrate, they expand, creating strong mechanical effect that stresses the rock; forcing grains to fall apart.
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What is hydrolysis?
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Is the decomposition process that breaks down silicate minerals into rocks. It involves water in chemical reations to produce chemical compounds.
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What is oxidation?
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Occurs when certain metallic elements combine with oxygen to form oxides.
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What is carbonation and solution?
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Reactions whereby carbon combines and transforms minerals containing calcium, magnesium, potassium, and sodium into carbonates.
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Fluvial
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Strem-related processes.
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What is erosion?
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Wind, water, and ice dislodge, dissolve, or remove surface material.
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Alluvium
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A general term for the clay, silt, and sand transported by running water.
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Drainage basin
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Spatial geomorphic unit occupied by a river basin.
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Watershed
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Drainage divides define these. They are the catchment area of the draining basin.
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