Chapters 2, 3, 4, 7, and 9 WOO! 2
Terms
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- The continental shelf and the steeper continental slope lie:
- Under water along the edges of continents.
- Submarine canyons are cut into the continental slope and outer continental by:
- Turbidity currents, sand flow and fall, bottom currents, and river erosion during times of lower sea level.
- What are turbidity currents?
- A flowing mass of sediment-laden water that is heavier than clear water and therefore flows donslope along the bottom of the sea or a lake.
- Abyssal fans form:
- As sediment collects at the base of submarine canyons.
- A passive continental margin occurs:
- Off geologically quiet coasts and is marked by a continental rise and abyssal plains at the base of the continental slope.
- The continental rise and abyssal plains form:
- From sediment deposited by turbidity currents.
- Continental rise may also form from:
- Sediment deposited by contour currents at the base of continental slope.
- Contour currents are:
- A bottom current that flows parallel to the slopes of the continental margin.
- An active continental margin is marked by:
- An ocean trench at the continental slope.
- What are associated oceanic trenches?
- Benioff zones of earthquakes and andesitic volcanism.
- What is the mid-oceanic ridge?
- A globe-circling mountain range of basalt, located mainly in the middle of ocean basins.
- What are fracture zones?
- Lines of weakness that offset the mid-oceanic ridge.
- Sea Mounts are:
- Conical, submarine volcanoes that are now mostly extinct.
- What are Guyots?
- Flattopped seamounts, probably leveled by wave erosion before subsiding.
- Chains of seamounts and guyots form what?
- Aseismic ridges.
- Corals and algae living in warm, shallow water construct what?
- Fringin reefs, barrier reefs, abd atolls.
- Terrigenous sediment is composed of what?
- Land-derived sediment deposited near land by turbidity currents and other processes.
- Pelagic sediment is composed of what?
- Wind-blown dust and microscopic skeletons that settle slowly to the sea floor.
- What does the mid-oceanic ridge lack?
- Pelagic sediment.
- Oceanic crust consists of what?
- Basalt pillows and dikes, probably overlying gabbro.
- Ophiolites in continental mountain ridges represent what?
- Slivers of somewhat atypical oceanic crust somehow emplaced on land.
- How old are the oldest rocks on the deep sea floor?
- 200 million years old.
- Plate tectonics
- The theory that the earth's surface is divided into large plates.
- Who is Alfred Wegener?
- A meteoroligist that proposed the theory of continental drift and Pangea.
- What evidence is there of continental drift?
- Careful fits of continental edges and detailed rock matches between now-sparated continents.
- What is Hess's hypothesis of sea-floor spreading?
- The sea floor moves away from the ridge crest and toward trenches as a result of mantle convection.
- Sea-floor spreading explains trenches as what?
- Sites of sea-floor subduction, which causes low heat flow and negative gravity anomalies.
- Sea floor spreading also explains what?
- The young age of rock of the sea floor as caused by the loss of old sea floor through subduction into the mantle.
- Plates are composed of what?
- Blocks of lithosphere riding on a plastic asthenosphere.
- What is Vine and Matthews?
- It's the hypothesis that gives the rate of plate motion and can predict the age of the sea floor before it is sampled.
- Divergent plate boundaries are marked by what?
- A narrow zone of shallow earthquakes along normal faults, usually in a rift valley.
- Transform boundaries are marked by what?
- By shallow quakes caused by strike-slip motion along one or more faults.
- Convergent plate boundaries can cause what?
- Subduction or continental collision.
- What are convergent plate boundaries marked by?
- Trenches, low heat flow, Benioff zones, andesitic volcanism, and young mountain belts or island arcs.
- Plate motion was once thought to be caused by what?
- Mantle convection.
- What is plate motion now attributed to?
- Cold, dense, leading edge of a subducting plate pulling the rest of the plate along with it.
- Trench suction:
- Helps continents to diverge.
- Mantle plumes are:
- Narrow columns of hot, rising mantle rock that cause flood basalts and may split continents , causing plate divergence.
- Earthquakes usually occur when?
- When rocks break and move along a fault to release strain that has gradually built up in the rock.
- Seismic waves move where?
- The move out from the earthquake's focus.
- Body waves move where?
- Move through Earth's interior.
- Surface waves move where?
- On Earth's surface.
- What are seismographs?
- A seismometer with a recording device that produces a permanent record of Earth motion.
- The time interval between first arrivals of P and S waves is used to determine what?
- The distance between the seismograph and the epicenter.
- Earthquake is determind and measured by:
- assessing damage and on the midfied Mercalli scale.
- How is magnitude tested?
- On the Eichter scale
- Most of the world's earthquakes are located where?
- The circum-Pacific belt.
- Convergent boundaries are marked by what?
- A very broad zone of shallow quakes and Benioff zones.
- Atoms are composed of what?
- protons, neutrons, and electrons. A given element always has the same number of protons.
- What is an ion?
- An atom in which the positive and negative electric charges do not balance.
- Ions or atoms bond together in what?
- Orderly 3-D crystalline structures.
- A crystalline substance is considered what?
- A mineral if it is naturally occurring and has a specific chemcial composition.
- The three most abundant elements in the earth's crust are what?
- Oxygen, silicon, abd aluminum.
- Most minerals are what?
- Silicates.
- What are the most common minerals in the earth's crust?
- Feldspars. The next are quartz, the pyroxenes, the amphiboles, and the micas. All silicates.
- Minerals are usually identified by what?
- Their physical properties.
- What are the physical properties?
- Cleavage, crystal form, fracture, hardness, luster, color, streak, and specific gravity.