Geology - Test 5
Terms
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- What is a plate?
- one of numerous rigid sections of the litosphere that moves as a unit over the material of the asthenosphere
- Which tectonic plate are we riding on right now?
- North American Plate
- Why do so few earthquakes of any consequence occur in North Dakota?
- no faults, no boundaries --- it'd have to be intra plate action i suppose
- Why does oceanic lithosphere subduct, while continental lithosphere doesn’t
- oceanic lithosphere is denser than continental lithosphere
- Name at least one plate that borders on (touches) the North American plate to our west, and one plate that borders on the North American plate to our east.
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Juan de Fuca
San Andreas Fault (not a plate)
Pacific Plate
Eurasian Plate
African Plate
South American Plate
Caribbean Plate
Cocos Plate - What is the most common igneous rock on the seafloor?
- basalt
- Who is most closely associated with the idea of Continental Drift?
- Wegener and Taylor
- Explain three pieces of evidence suggesting that now-separate continents were once connected.
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*The continental jig-saw puzzle*
-the continents fit together
*Fossils match across the sea*
-Mesosaurus
*Rock type and structures match*
*Ancient Climates* - What was Mesosaurus?
- fresh water reptile
- What was Glossopteris?
- a plant with big seeds
- What was the fundamental problem with the Continental Drift idea? (That is, why wasn't it a workable idea in its original form?)
- ----?
- Compare the mechanism by which continents move in the old Continental Drift idea with the mechanism by which continents move in the modern Plate Tectonics idea.
- -----?
- Although there are several different tectonic plates ("plates"), there are only three different kinds of plate boundaries (different ways the plates touch each other). What are the three kinds of plate boundaries?
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convergent
divergent
transform faults - Explain what happens at a divergent boundary. Go into specifics about the geologic phenomena (for example, the nature of earthquakes, kinds of volcanic and/or magmatic activity, if any).
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*rift valleys*
*seafloor spreading*
upwarping-riftvalley-linearsea-midocean rift - Explain what happens at a convergent boundary. Go into specifics about the geologic phenomena (for example, the nature of earthquakes, kinds of volcanic and/or magmatic activity, if any).
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*subduction zones*
*continental volocanic aracs*
*volcanic island arc*
*mountains...?* - What is a Benioff Zone? (Since Benioff Zones were discovered before Plate Tectonics, do not use Plate Tectonics in your answer. Just say what Benioff Zones are.)
- ---
- With what type of plate boundary are Benioff Zones associated?
- convergent
- How does Plate Tectonics explain Benioff Zones (i.e., what is going on there)?
- ----
- What is the asthenosphere?
- a subdivision of the mantle situated below the lithosphere. This zonoe of weak material exists below depth of about 100 kilometers and in some regious extends as deep as 700 kilometers. The rock within this zone is easily deformed
- What is the role of the asthenosphere in Plate Tectonics?
- --?
- What kind of plate boundary is the mid-Atlantic Ridge? What is happening there?
- divergent - seafloor spreading
- Why are there so few earthquakes along the east coast of the U.S.?
- no faults?!
- What kind of plate boundary separates the North American Plate from the Eurasian Plate?
- divergent
- What kind of plate boundary separates the North American Plate from the Juan de Fuca Plate?
- transform fault
- What kind of plate boundary separates the North American Plate from the Pacific Plate?
- convergent?
- Name two places on the globe where small, new ocean basins are opening up.
- ?
- What kind of igneous activity occurs in the vicinity of a divergent plate boundary? (Be specific. I am looking for the rock name and how it is classified (which tells something about how it formed).)
- ---?
- What kind of igneous activity occurs in the vicinity of a convergent plate boundary? (Be specific.)
- ---?
- Which kind of plate boundary is associated with the least igneous activity?
- ---?
- How does intrusion of granite fit into the Plate Tectonic model?
- ?
- What is the relationship between granite and andesite in the Plate Tectonic model?
- ?
- Which type of plate boundary is associated with andesitic volcanism?
- ?
- Which type of plate boundary is associated with granitic plutonism?
- ?
- What kind of plate boundary is the San Andreas Fault?
- transform
- What is a "subduction complex"?
- ?
- What is an "accretionary wedge"?
- ?
- What is "tectonic melange"?
- ?
- What happens at a "hot spot"?
- a proposed concentration of heat in the mantle capable of introducing magma that in turn extrudes onto Earth's surface. The intraplate volcanism that produced the Hawaiin Islands is one example
- What is a mantle plume?
- a mass of hotter-than normal mantle material that ascends toward the surface, where it may lead to igneous activity. These plumes of solid yet mobile material may originate as deep as the core-mantle boundary
- Distinguish between the technical meanings of "stress" and "strain."
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stress - the force per unit area acting on any surface with in a solid
strain---resultant of stress - Define tension.
- ?
- Define compression.
- ?
- Describe shear.
- stress that causes two adjacent parts of a pudy to slid past one another
- Describe elastic deformation. What do we mean when we say deformation is "elastic"?
- nonpermanent deformation in which rock returns to its original shpae when the stress is realeased
- What is brittle deformation?
- ?
- What is plastic ("ductile") deformation?
- ?
- Qualitatively, what sort of conditions (in terms of amount of stress, confining pressure, and the element of time) favor (1) elastic deformation; (2) brittle deformation; (3) plastic deformation?
- ?
- What's a horst/graben?
- ?
- What specific kind of geologic structure is produced by brittle failure due to shear stress?
- ?
- What specific kind geologic structure is produced by brittle failure due to compressional stress?
- ?
- Define strike and dip.
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strike - exhibit mainly horizontla displacement parallel to the fault surface (tranform)
dip - normal and reverse - primarily vertical