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60 Cards in this Set
- Front
- Back
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Mafic magmas contain about what percent silica?
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50%
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Which type of volcano is not usually made of basalt?
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Composite
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What is the major difference between intrusive igneous rocks and extrusion igneous rocks due to?
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Where it cools
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Why don't flood basalts build volcanic cones?
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Because flood basalts have very low viscosity
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What determines whether volcanic eruptions are very explosive or relatively quiet?
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The viscosity
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What tectonic plate are you presently on?
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North American
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Why do mafic magmas tend to reach the surface much more often than silicon magmas?
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Mafic magmas have a much lower viscosity
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What rock would probably for if magma that was feeding volcanoes above subduction zones solidified at considerable depth?
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Diorite
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What determines viscosity of lava?
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Silica content, temperature, and gas content
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What is a surface separating different rock types called?
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Contact
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The ability of a mineral to break along preferred direction is called
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Cleavage
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3 major types of rock?
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Igneous, sedimentary, metamorphic
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What are atoms of an element containing different numbers of neutrons but the same number of protons called?
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Isotopes
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How would you distinguish quartz and feldspar based on their physical properties?
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Quartz scratches feldspar
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What is the most common igneous rock type of continental crust?
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Granite
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What are the three most common elements in earth's crust?
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Oxygen, silicon, aluminum
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What is a substance that cannot be broken down into another substance called?
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Element
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How do oceanic and continental crust differ?
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Continental crust is thicker and less dense than oceanic
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Explain why cavemen never saw dinosaurs.
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Lived at different times
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What is the most likely geological hazard in your part of the country?
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Flash flooding
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Why is it desirable to find an index fossil?
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It allows correlation of rocks worldwide
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Geological processes operating at present are the same processes that have operated in the past
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Uniformitarianism
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If rock A cuts rock B, is A older or younger than rock B?
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Younger
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Within a sequence of undisturbed sedimentary rocks, the layers get younger going from bottom to top
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Superposition
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How do regional metamorphic rocks differ in texture from contact metamorphic rocks?
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Regional metamorphic rocks ate foliated
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What is the correct sequence of rocks that are formed when shale undergoes prograde metamorphism?
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Shale to slate, phyllite, schist, gneiss
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What are the various sources of heat for metamorphism?
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Pressure, temperature, magma bodies in earth's core
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How would you distinguish a quartzite from a marble?
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Limestone fizzes with acid, quartzite scratches glass
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Limestone recrystallizes during metamorphism into what rock?
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Marble
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What do mud cracks tell about the environment of deposition of a sedimentary rock?
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Alternate wet and dry conditions
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Name the three most common sedimentary rocks
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Limestone, sandstone, shale
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What is the major difference between breccia and conglomerate?
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Conglomerate has rounded grains
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How do evaporates form?
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Evaporation of saline h20
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Name 2 evaporates
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Rock salt and gypstone
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Describe at least three processes that mechanically weather rocks
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Frost wedging- freeze and thaw h20 in cracks.
Root wedging- roots grow in cracks Pressure release- exfoliation joints in granite |
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What is the single most effective agent of chemical weathering at Earth's surface?
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Carbonic Acid
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What is the most common end product of the chemical weathering of feldspar?
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Clay
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How can mechanical weathering speed up chemical weathering?
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Increases surface area
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Why do stone buildings tend to weather more rapidly in cities than in rural areas?
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Acid rain
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Why do sedimentary rocks often have a reddish brown color?
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Because of the small percentage of iron which oxidizes
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What is the evidence that South America and Africa were once joined?
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The rocks and fossils found on both continents were similar
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How does sea floor spreading account for the age of the ocean floor?
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No rocks over 2 million years old.
The further from the fault, the older the rocks get. |
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Define lithosphere and asthenosphere.
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Lithosphere is the crust and upper mantle which is solid. Where as the asthenosphere is below and is soft.
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Discuss possible driving mechanisms for plate tectonics.
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Convection currents in mantle
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What is transform fault?
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Plates move sideways past each other. Ex: San Andreas Fault
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Describe the differences between oceanic and continental crust
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Oceanic is thinner and more dense than continental crust.
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What facts make it probable that Earth's core is composed mainly of iron?
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Average density of earth is 5.5 which means the core is very heavy like iron. 10% of meteorites have iron, nickel composition
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What is the principle of continents being in buoyant equilibrium called?
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Isostacy
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What is the Mohorovicic discontinuity?
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It is the contact between the crust and mantle
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Discuss seismic wave shadow zones and what they indicate about the earth's interior.
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P wave shadow zones indicate presence of core. S wave shadow zones outer core is liquid
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Discuss the distribution of earthquakes with regard to location and depth of focus.
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Along plate boundaries. Convergent plate boundaries have deep foci where as divergent have shallow
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What is the point within earth where seismic waves originate called?
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Focus
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Name and describe the various types of seismic waves.
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Body waves
P waves- fastest waves S waves- come after p waves and only travel through solids. Surface waves deal the most damage |
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How do earthquakes cause tsunami?
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Offset of the ocean bottom
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A zone of shallow earthquakes along normal faults is typical of what type of plate boundary?
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Divergent
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What are fractures in bedrock along which movement has taken place called?
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Faults
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What factors control whether a rock behaves as a brittle material or a ductile material?
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Pressure, temperature, type of rock, and the strain it has
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What is a structure in which the bed dips away from a central point and the oldest rocks are exposed in the center called?
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Structural dome
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What is the compass direction of a line formed by the intersection on an inclined plane with a horizontal plane called?
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Strike
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What type of faulting is associated with tensional stress and crustal stretching?
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Normal faults
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