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198 Cards in this Set
- Front
- Back
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What are the two primary types of waves generated by earthquakes?
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-surface waves and body waves
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Name two types of body waves
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-P waves and S waves
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Where do body waves and surface waves travel?
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-Body waves travel within Earth, and surface waves travel along Earth's surface.
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What do vertical and horizontal surface waves have in common?
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-Both waves travel along Earth's surface and decrease in amplitude with depth below the surface.
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How do rocks within Earth change as P waves pass?
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-Rocks within Earth both expand and contract as P waves pass.
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How does rock within Earth change as S waves pass?
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-Rocks within Earth are displaced up and down as S waves pass.
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How are S waves and vertical surface waves different?
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-S waves are body waves, whereas vertical surface waves are surface waves. The amplitude of S waves does not decrease with depth, but the amplitude of vertical surface waves does decrease with depth.
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what are the four primary zones in Earth's interior?
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-crust, mantle, outer core, inner core
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What data provided information about the existence of different zones within Earth?
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-P-wave and S-wave arrival times
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Which of the following statements about seismic wave ray paths is most accurate?
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-Seismic waves move along curved ray paths because of changing properties of rocks.
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Why do we believe Earth's outer core is a liquid?
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-P waves slow down and refract at the boundary between the mantle and the outer core.
-S waves do not travel through the outer core. |
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Why do geologists believe the inner core is solid?
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-P waves refract at the boundary between the outer core and inner core
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How could you test whether the core of another planet were completely solid?
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-Set off a bomb to create seismic waves. If S waves arrive on the opposite side of the planet, then the core is solid.
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What is a seismograph?
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-A seismograph is an instrument used to record earthquake waves.
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What is the underlying principle of seismograph construction?
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-A heavy weight suspended within a moving box needs to overcome inertia, resulting in a slight delay in the motion of the weight after the box moves
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When will the first earthquake waves arrive at a seismograph station?
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-a short time after the earthquake occurs
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What is the longest amount of time that might occur between earthquake occurrence and arrival of the first earthquake waves at a seismograph?
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-several minutes
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What was the response by the scientific community when Alfred Wegener published The Origin of Continents and Oceans in 1915?
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-His ideas were generally viewed with disbelief, rejected, and considered improbable or impossible
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How do plates move at divergent plate boundaries?
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-Plates move apart.
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How do plates move at convergent plate boundaries?
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-Plates move together
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How do plates move at transform plate boundaries?
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-Plates move side by side.
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In general, where do both earthquakes and volcanic eruptions occur?
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-at divergent plate boundaries
-at convergent plate boundaries |
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What forms at divergent plate boundaries?
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-new oceanic lithosphere
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In general, where do volcanoes form in subduction zones?
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-on the overriding plate, away form the convergent boundary
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Why are volcanoes not found at transform boundaries?
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-Transform boundaries do not cause changes to the pressure, temperature, or composition of the mantle.
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The East African rift is a divergent plate boundary that is splitting the continent of Africa into two pieces. What will eventually form around this divergent boundary?
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-an ocean
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Where are tectonic plates located?
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-at Earth's surface
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What are the three types of plate boundaries?
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-divergent, convergent, and transform
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Which of the following statements about earthquakes with magnitude greater than 4.0 is most accurate?
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-Earthquakes with magnitude greater than 4.0 occur in a pattern than correlates closely with plate boundaries.
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Which plate boundary is NOT associated with volcanic eruptions?
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-transform
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Which phenomenon can explain the presence of volcanoes in the middle of the Pacific Ocean?
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-hot spots
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Which type of plate boundary is most closely associated with uplifting continental regions and mountain building?
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-convergent boundaries
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Which type of plate boundary is most closely associated with the formation of new ocean floor?
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-divergent
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Which of the following statements about Earth's magnetic field is most accurate?
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-Earth's magnetic field switches polarity at irregular time intervals.
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How often does the Earth's magnetic field switch polarity?
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-every 100,000 to several million years
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How are normal polarity and reverse polarity of Earth's magnetic field different?
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-A compass points toward the North Pole during normal polarity and to the South Pole during reverse polarity
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In general, what is our best evidence that the orientation of Earth's magnetic field has changed over time?
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-A record of Earth's magnetic field is recorded in oceanic rocks, which show a clear pattern of changes in Earth's magnetic polarity.
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Where would you expect to see alternating bands of rock with different magnetic polarities?
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-on both sides of the mid-ocean ridge
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Which mountain belt lies to the north of India?
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-the Himalayas
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In general, what are the Himalayan mountains composed of?
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-folded and faulted rock
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Which of the following statements is most accurate?
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-A moving India collided with a stationary Asia about 30 million years ago.
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Which of the following statements is most accurate about Tibet?
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-Prior to 30 million years ago, Tibet was a much thinner landmass than it is today.
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Which type of plate boundary exists between India and Asia today?
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-a convergent boundary
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Why didn’t India subduct under Asia?
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-The two continents have similar densities.
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Did any subduction occur during the collision of India and Asia?
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-Yes; ocean basin between these two continents subducted under Asia
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Which location is the result of oceanic-continental convergence?
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-The Cascades and Mt. St. Helens
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What is a terrane?
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-a slice of lithosphere that has been added to the margin of a continent during plate collision
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Where does most terrane accretion occur?
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-in association with a continental-oceanic subduction zone
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Why are terranes added to continental margins, rather than subducting under them?
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-Terranes are too buoyant to subduct
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hich of the following statements about terranes is most accurate?
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-The margins of many continents have grown through the accretion of terranes.
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How do the Hawaiian Islands support tectonic plate theory?
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-They are a hot spot and show plate movement.
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What geologic process is related to caldera formation?
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-volcanism
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How do calderas form?
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-Calderas form when the summit of a volcano collapses
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Where is Crater Lake?
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-Oregon
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Why does Crater Lake have an island in it?
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-The volcano is still active, and a new volcanic peak has formed
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Which of the following are types of volcanoes?
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-Cinder cone
-Shield volcano -Composite volcano |
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What information do geologists use to classify volcanoes?
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-Shape and type of deposits
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Cinder cones are made of________.
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-pyroclastic deposits
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how often do most cinder cones erupt?
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- once
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What are shield volcanoes generally made of?
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-Basalt flows
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What is the range of shield volcano height?
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-300 to 10,000 meters
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What are composite volcanoes made of?
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-Pyroclastic deposits
-Basalt flows |
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Why are shield volcanoes wider than composite volcanoes?
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-The lava that flows out of shield volcanoes is more fluid than the lava that flows out of composite volcanoes
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What type of magma erupts out of dome complexes?
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-Felsic magma
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What type of volcanoes are the tallest?
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-Shield volcanoes
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What is the range of dome complex height?
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-500 to 2,000 meters
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What is a fault?
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-fractures along which rocks move
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What are rocks below and above a fault called?
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-the footwall below and the hanging wall above
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Which type of force is responsible for normal fault formation?
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-tensional force
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Which type of force is responsible for reverse fault formation?
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-compressional force
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Which type of force is responsible for normal strike-slip formation?
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-shear force
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Which type of fault has NO vertical motion of rocks associated with it?
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-strike-slip fault
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What is an explosive volcanic eruption of hot gases, ash, and rocks that burns and buries things in its path?
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-Pyroclastic flow
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What are the types of mountain glaciers, and how are they related?
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-A cirque glacier can become a valley glacier and then a piedmont glacier.
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How does a nunatak form?
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-Mountain glaciers accumulate sufficiently to isolate and surround a mountain peak
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Where do glaciers form?
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-in places where more snow falls in the winter than melts away in the summer
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What is the snow line?
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-the elevation above which snow persists throughout the year
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What is the zone of wastage?
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-the part of a glacier where snow melting exceeds snow accumulation
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Under what conditions will the front of a glacier remain stationary?
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-Glacial fronts remain stationary when melting and snow accumulation are equal
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What is an end moraine?
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-a ridge of debris deposited at the end of a glacier
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How does an end moraine form?
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-Pieces of rock are transported to the front of a glacier as ice within the glacier moves
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Will plucking occur if a glacier is not advancing?
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-Yes, because glacial ice is still moving inside the glacier even if the glacier’s front is not advancing
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What is the impact on a glacier in a year when melting exceeds snowfall?
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The area of the glacier shrinks.
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What is the ocean-filled portion of a previously glaciated valley called?
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-Fjord
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Which glacial landform can be found beyond the extent of the ice?
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-Outwash plain
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What is the process that breaks rock material into smaller pieces by atmospheric and biotic agents?
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-Weathering
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What impact do rock openings have on weathering processes?
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-They increase the surface area exposed to weathering.
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What type of rock opening is most important in facilitating weathering?
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-Joints
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Why does water frozen in the cracks of a rock help to break down the rock?
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-Water expands when frozen and physically forces the rock apart
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What is salt weathering?
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-The formation of minerals in rock cracks during the evaporation of salty water, forcing rock apart.
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What do freeze-thaw and salt weathering have in common?
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-Both freeze-thaw and salt weathering require rain and force rocks apart physically.
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What is the agent of erosion associated with mass wasting?
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-Gravity
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In which location would frost wedging have the most impact?
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-Maine
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Which statement correctly describes the impact of climate on weathering?
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-Weathering is least active in deserts
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Which of the following are classifications describing how rock and other material move downslope?
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-fall, slide, slump, creep, flow
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What is mass movement?
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movement of material under the influence of gravity alone
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How is a fall different from creep?
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-Falls occur rapidly and in areas with high slope, whereas creep occurs slowly in areas with low slope
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How are slumps and slides related?
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-Slumps are a type of slide in the special case where the rupture surface is curved.
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How are debris avalanches and flows related?
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-Debris avalanches are large, rapid flows of rock.
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Which type of mass movement event requires the addition of water?
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-flow
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How does water influence mass wasting?
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-Water acts as a lubricant.
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What type of mass wasting involves the greatest amount of water?
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-Flow
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What is the distinctive trait of a slump?
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-Slumps involve movement along a curved surface
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How do mudflows and earthflows differ?
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-Mudflows are the wettest type of mass wasting.
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What is described by the statement that a stream moves a cubic meter of material past the stream gage every day?
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-Capacity
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How can pieces of rock in contact with a stream bed move?
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-rolling, sliding, bouncing
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Complete this analogy: Bouncing is to sand as suspension is to_____________.
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-clay
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Sliding is to gravel as dissolution is to_____________.
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-ions
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Which of the following are part of the bed load?
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-sand and gravel
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What are the three types of loads carried by streams?
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-bed load, suspended load, dissolved load
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What is suspended load?
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-the fine-grained particles that travel in the water column above the stream bed
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What is the drainage pattern of the streams on Mt. Vesuvius in Italy?
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-Radial
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What causes stream capture?
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-Headward erosion by an adjacent stream with a steeper gradient destroys the drainage divide.
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Why does a delta form?
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-Stream velocity slows sufficiently that the load is dropped.
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What is a floodplain?
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-a flat surface next to a river channel
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What is a natural levee?
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-a ridge of flood deposits next to a river channel
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How does the formation of a natural levee impact flooding?
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-Natural levees raise the height of the stream channel, reducing the amount of flooding that will occur on the floodplain
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What type of stream is associated with the formation of an oxbow lake?
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-meandering stream
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What is the dominant fluvial process in a clear, sediment-poor stream moving down a steep slope?
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-downcutting
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Which processes result in the widening of the floodplain of a meandering stream?
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-undercutting and lateral erosion
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Where do deposition and erosion of material occur along a meander?
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-Deposition occurs on the inside of the meander, whereas erosion occurs on the outside.
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What is an oxbow lake?
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-Oxbow lakes form when one meander erodes into another, cutting off water to part of the stream channel.
-a meander that has been cut off from the original stream channel |
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What is a meander scar?
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-a landscape feature formed after an oxbow lake dries up
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Which sequence is correctly ordered from first to last in the development sequence?
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-Meander, cutoff, oxbow lake, and meander scar
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When do stream terraces form?
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-when streams exist under alternating erosional and depositional conditions
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When do streams erode laterally?
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-when downcutting is occurring in easy-to-erode sediment or rock
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What is a stream terrace?
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-a remnant of an older floodplain that sits above the stream valley
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How many stream terraces can exist along a single valley?
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-No limit exists. Stream terraces will keep forming as long as lateral erosion and downcutting continue.
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Are stream terraces depositional or erosional landforms?
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-Stream terraces can be either depositional or erosional.
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denudation
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-total effect of all actions (weathering, mass wasting, erosion) that lower the surface of the continents
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weathering
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-physical and chemical disintegration of rock that is exposed to the atmosphere
-first process in shaping the surface (denudation) |
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mass wasting
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-short-distance downslope movement of weathered rock under the influence of gravity
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erosion
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-Detachment, removal, and transportation of fragmented rock material
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talus
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-pieces of weathered rock of different sizes that fall due to downslope
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What is the relationship between mass wasting and gravity?
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-the greater the mass the larger the gravitational force
-stress -the lower levels have more stress |
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rock fall
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-mass wasting in which weathered rock drops to the foot of a cliff or steep slope
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Earth flow
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-mass wasting in which a portion of a water saturated slope moves a short distance down hill
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Mud flow
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-Rapid, downslope movement of dense mix of weather rock and water through or within a valley
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landslide
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-abrupt and catastrophic event
-large mass of rock and soil slides downslope in a few mins or secs -collapse of a slope |
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What three things happen to the terrain after a landslide?
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1. deep scare, exposing bedrock
2. Mass material chokes the valley at the bottom 3. produces and new lake by blocking the bottom stream |
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Fault
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-breaks in bedrock
-occur in small numbers -appear in major landscape features -allow easy penetration of weathering agents |
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Joints
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-cracks that develop as a result of stress
-numerous -minor structures not extending far |
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Why is clay a facilitator of mass wasting?
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-clay absorbed water
-makes things slippery -anything resting on clay can be set in motion by rainfall or earthquake |
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solifluction
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-gradual movement of wet soil or other material down a slope
-"creeps" that produce distinct surface appearance -high altitudes and elevation tundras -summer ground thaws, melt water can't go deeper because of permafrost -erratic and irregular movement |
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When you see a titled telephone pole on a hill, what is the most likely explanation for this tilt?
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-creep
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exfoliation
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-curved layers peel off bedrock "onion"
-smoothes the landscape -unloading stress form crystalline rocks |
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Describe the ways that mechanical weathering can occur.
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-frost wedging= freeze and thaw action
-salt wedging= salt crystalizes as water evaporates -temp changes= can change the volume of mineral particles causing expansion and contraction |
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hydrolysis
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-chemical union of water with another substance to produce a new compound that is weaker than the orginial
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Why is water such an important agent in weathering? What happens to water when it freezes and what effect does that have on weathering?
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-dissolves rocks and enhances the effects of chemical weathering
-it expands and contracts |
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How does most biological weathering occur?
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-penetration of growing plant roots into cracks
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In what types of climates is weathering most likely to occur?
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-shallow in tundras and deserts
-deep in tropical rainforest |
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salt wedging
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-salt crystalizes out of solution as water evaporates
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Frost shattering
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-freezing and thawing
-much more effective mechanical weathering |
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Pangaea
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-massive super continent existing 225 mya then broke apart into large sections
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Explain how the presence of the Mid-Atlantic Ridge supports the theory of plate
tectonics. Why does the rock get increasingly older as you move away from the mid-ocean ridges? |
-runs halfway between and matches the shape of the coastlines on both sides
-subduction (recycled) defends into the asthenosphere |
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Divergent plate boundary
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-2 plates diverge from one another (spread apart)
-magma comes up in openings between plates -produces line of volcanic vents that spill out lava on the the ocean floor (mid ocean ridges rift valleys) -spreading, shallow earth quakes Red sea |
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Convergent boundary
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-2 lithospheric plates collide
-destructive -removal or compression of surface crust -Mt., volcanoes, and ocean trenches -oceanic-continental, oceanic-oceanic, continental-continental |
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transform boundary
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-2 plates slip past one another laterally
-neither create new crust nor destroy old -a lot of seismic activity -shallow focused earthquakes -san Andres fault in Cali |
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Explain the Hawaiian Islands in terms of mantle plumes.
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-terrane is too buoyant to be sub ducted in the collision so it is fused to other plates
-accretionary wedges -accreted terranes |
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Why is there such a concentration of earthquakes and volcanoes around the
margin of the Pacific Ocean? What is this called? |
-Pacific ring of fire
-plate boundaries are found all around the Pacific basin -subduction zones, segments of transform and divergent boundaries |
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How were the Himalayas formed? How were the Andes formed?
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Himalayas= continental-continental convergence continental collision
Andes= compression due to the convergent plate boundary. South america was forced against the Nazea plate |
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What is the definition of an active volcano? Where are most of the volcanoes
located in the United States? |
-if it has erupted at least once within historical times and is likely to do it again
-Cascade Range Pacific northwest |
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What were some of the effects of the Mt. St. Helens’ eruption? Why are
volcanoes sometimes considered beneficial? |
-they can be beneficial because water is released as water vapor, magma and ash mix with soil to provide nutrients for plant growth
-reduced elevation, $1 billion in damages, and 57 people died -clogged the columbian river and spread ash 22,000 miles |
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What is North America’s most famous caldera? How was it formed?
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-crater lake
-during an eruption, the walls weakened and collapsed -emptying the magma chamber -filled with water |
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graben
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-a portion of the earth's crust, bounded on at least two sides by faults, that has dropped downward in relation to adjacent portions.
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Horst
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-uplift of a block of land between 2 parallel faults
-results of the land on both sides being down thrown rather than the block being uplifted |
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Diastrophism
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-aka Tectonism
-rocks may be bent or broken in response to great pressure exerted in crust or mantle |
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folding
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-bending of crustal rocks by compression or uplift
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faulting
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-fracture or zone fracture
rock structures are forcefully broken and 1 side is displaced relative to the other -horizontal or vertical or both |
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anticline fold
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-simple symmetrical up-fold in the rock structure
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syncline fold
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-down-fold in rock structure
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overturned fold
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-pushed so much from 1 side it becomes over steepened
-reverse orientation on the other side |
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overthrust fold
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-created by compression
-forcing the upthrown block to override the down thrown block at a low angle. -older rocks to rise above younger rocks |
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Which mountain range is a series of ridge and valleys caused by folding?
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-up-fold Anticlines produce ridges
-syncline down-folds produce valleys -Appalachian Mountains |
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magma
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-molten material below Earth's surface
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LAVA
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-molten magma that is extruded onto the surface of Earth
-cools and solidifies |
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Lahar
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-volcanic mudflow
-fast moving muddy flow of ash and rock |
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Pyroclastic material and flow
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-solid rock fragments thrown into the air by volcanic explosions
-high speed avalanche of hot gases, ash and rock |
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Flood basalt
Where are prominent flood basalt formations located? |
-large scale out pouring of basaltic lava that may cover an extensive area of Earth
-covers a lot of land -mass extinction -Deccan Traps, India and Siberian Traps and Columbian River in N. America |
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Lava flow
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-spreads outward parallel with the surface that it is flowing from
-stacking |
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What is the difference between an earthquake’s focus and its epicenter?
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-the strongest shocks and creates vibrations are felt on the ground above the focus at the epicenter
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Batholith
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-largest and most amorphous of igneous intrusions
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Caldera
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-large steep side, circular depression
-resulting from explosion or collapse of a volcano |
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Continental drift
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-continents were originally connected as one or two large land masses that broke up and drifted apart
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Dike
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-vertical sheet of magma that is thrust upward into preexisting rock
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Fault-block Mountain
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-Mnt. formed where surface block is faulted
-upthrown on one side w/o any faulting or uplift on the other side block is tilted -producing a slope |
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strike-slip fault
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-side to side
-horisontal movement -shear stress |
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Fault scarp
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-steep cliffs
-vertically displaced block |
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Hot spot
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-and area of volcanic activity within the interior of a plate
-magma rising up from the mantle |
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Laccoliths
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specialized form of intrusion produced slow-flowing, viscous felsic magma
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Mantle plume
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-plume of mantle magma that rises to earths surface
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Monocline
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-one sided fold
-connecting two horizontal inclined strata |
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Oceanic trenches
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-narrow and deep
-occur around margins of ocean basins |
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off set stream
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-a stream course displaced by lateral movement along a fault
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Plate tectonics
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-massive rearrangement based on movement of continent sized plates
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sag pond
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-caused by a collection of water into sunken ground
-resulting from crushing go rock in an area of fault movement |
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sea floor spreading
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-pulling apart of plates to allow rise of magma to the surface
-mid-ocean ridges |
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subduction
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-descent of the edge of an oceanic plate under the edge of an adjoining plate
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