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SALT
SALT 9th Science - Chp 8
| Question | Answer |
|---|---|
| geology | study of the earth |
| crust | the earth’s outer layer of rock; thinnest beneath the oceans |
| oxygen | the most abundant element in the earth’s crust |
| granite | composes the portion of the earth’s crust underlying the continents |
| basalt | composes the portion of the earth’s crust underlying the oceans |
| sediments | deposits of sand and mineral fragments, usually laid down by water |
| Mohorovičić discontinuity (Moho) | boundary between the crust and the mantle |
| mantle | the middle layer of earth between the crust and the core (upper and lower mantle); like the crust, the mantle is solid rock |
| transition zone | zone in between, where the upper mantle merges into the lower mantle |
| plastic rock | rock in the mantle with some properties of a solid and some properties of a liquid |
| Gutenberg discontinuity | boundary between the bottom of the mantle and the core |
| core | the central portion of the earth’s interior (outer core seems to be liquid, and the inner core of the earth inner core is thought to be solidthought to be solid due to pressure) |
| plate tectonics | the theory that states that the earth’s crust and upper mantle consist of huge plates that slowly drift as a result of convection currents in the mantle |
| theory of plate tectonics | states earthquakes and volcanoes are far more likely to occur at the edges of plates |
| Pangaea | According to the continental drift hypothesis, all the present-day continents were at one time connected into this huge land mass |
| fault | a fracture in a rock that occurs when the rock breaks under the strain of the forces upon it |
| normal fault | type of fault that results when rocks along one side of a fault sink vertically |
| strike-slip fault | type of fault that results when rocks along one side of a fault move horizontally along the fault |
| thrust fault | type of fault that results when rocks on one side of a fault move on top of the rocks on the other side |
| fold | is formed by the bending of buckling of rocks under great force |
| syncline | troughlike structure formed when rocks are folded downward |
| anticline | archlike structure formed when rocks are folded upward |
| volcanic mountains | type of mountains apparently formed when molten rock erupts from a hole in the earth’s crust |
| domed mountains | type of mountains apparently formed when molten rock collects beneath an overlying rock layer, forcing the layer upward into a blisterlike structure |
| folded mountains | type of mountains apparently formed when the edges of two adjacent rock layers are pushed violently together, causing the layers to buckle like a wrinkled rug |
| fault-block mountains | type of mountains apparently formed when rocks on one side of a fault are forced upward and the rocks on the other side are forced downward |
| earthquake | a trembling or shaking of the earth’s crust |
| tremor | a weak earthquake (with a magnitude of less than about 3) |
| aftershocks | small earthquakes that often follow a larger earthquake at frequent intervals for days or even months |
| seismology | study of earthquakes |
| faulting | the sudden movement of rock masses along a fault |
| elastic rebound theory | states that rocks spring back to a position of little or no strain at the moment of an earthquake, causing vibrations in the earth’s crust |
| San Andreas fault | a large, well-known strike-slip fault in western California |
| focus | the point deep in the earth at which an earth quake begins |
| epicenter | the point on the earth’s surface directly above the point at which an earthquake begins |
| P-waves (primary waves) | earthquake waves consisting of a rhythmic push-pull motion in the direction of wave travel; fastest type of earthquake waves |
| S-waves (secondary waves) | earthquake waves consisting of a rhythmic side-to-side motion that occurs at right angles to the direction of wave travel; they can produce a lot of damage to buildings |
| surface waves | earthquake waves that travel along the earth’s surface |
| seismograph | an instrument used to record the vibrations caused by earthquakes |
| Circum-Pacific belt | area where about 80% of the world’s earthquakes occur |
| Mercalli scale | a scale with 12 degrees of intensity describing and measuring the effect of an earthquake on man, man’s structures, and the earth’s surface |
| Richter scale | the most famous scale used to measure earthquake strength, which rates earthquakes on a scale of 1 to 10 |
| volcano | an opening in the earth’s surface through which hot gases, ash, and molten rock are ejected from the earth’s interior |
| vent | the channel in a volcano through which gases, ash, and molten rock are ejected from the earth’s interior |
| magma | molten rock beneath the surface of the earth |
| volcanology | the study of volcanoes and volcanic phenomena |
| cinder-cone volcano | type of volcano consisting primarily of erupted volcanic ash and rock fragments held loosely together |
| shield volcano | broad, gently sloping volcano built up of large quantities of highly fluid lava that harden into rock |
| composite volcano | volcano formed partly by explosive eruptions of ash and rock fragments and partly by mild lava flows |
| active volcano | has erupted in the last 50 years |
| dormant volcano | has not erupted in the last 50 years, but may erupt again |
| extinct volcano | will probably not erupt again |
| Ring of Fire | the most important volcanic belt, a narrow zone of active volcanoes that nearly encircles the Pacific basin |
| ejecta | any substance emitted by an active volcano |
| lava | molten rock that flows from volcanoes |
| pahoehoe lava | lava that hardens into a smooth-textured rock with a “ropy” appearance |
| aa lava | lava that hardens into rough, jagged rocks with a crumbly texture |
| pyroclasts | particles or blocks of solid volcanic ejecta |
| pyroclasts range in size | volcanic ash, volcanic cinders, volcanic blocks, and volcanic bombs. |
| volcanic bomb | large almond- or teardrop-shaped pyroclasts formed when lava solidifies while hurtling through the air |
| nuée ardent | a superheated, incandescent cloud of gas and volcanic ash that flows swiftly down a volcanic slope as an avalanche |
| caldera | a huge bowl-shaped crater in the ground more than 2 miles wide, formed by the collapse of an underground magma chamber |
| lava tunnel | an underground tunnel formed when the surface of a large lava flow hardens before the lava beneath |
| igneous intrusions | a mass of igneous rock beneath the earth’s surface |
| dike | vertical, sheetlike igneous intrusion formed when magma hardens in a vertical crack or fissure |
| sill | horizontal, sheetlike igneous intrusion formed when magma hardens in a horizontal crack or fissure |
| laccolith | domelike igneous intrusion formed when magma bulges overlying rocks upward |
| batholiths | an igneous intrusion similar to a loccolith but much larger; commonly forms the base of great mountain ranges |
Created by:
kbtarheelgirl
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