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60 Cards in this Set

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