GEOL 101: EXAM 1
95 Cards in this Set
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Principles Of Geology
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Core, Mantle, Crust
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Core, Mantle, Crust
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It is lower density than the mantle
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The radius of the Earth's core is 3486 km and the thickness of the mantle, which surrounds the core, is 2900 km. Therefore, the volume of the mantle is ____ the volume of the core.
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Much more than.
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Much more than.
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Continental Crust
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The ___ forms the relatively cool, brittle plates of plate tectonics.
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Lithosphere.
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Which one of the following best characterizes the asthenosphere?
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A zone of softened peridotite and magma in the upper mantle.
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Which of the following best describes the hypothesis of seafloor spreading?
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Rising material in the mantle spreads laterally, carrying the seafloor away from seafloor ridges in the center of the ocean basin.
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Which of the following energy sources is thought to drive the lateral motions of Earth's lithospheric plates?
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Export of heat from deep in the mantle to the top of the asthenosphere.
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Why is so much basaltic magma erupted along mid-ocean ridges?
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Lowered pressures decrease the temperatures at which basalt magma can partially melt from a rising plume of mantle peridotite.
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'Black smokers’ in the ocean are:
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Submarine hot springs on mid-ocean ridges
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Cooler, older, oceanic lithosphere sinks into the mantle at:
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Subduction zones along convergent plate boundaries.
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The Hawaiian Islands become younger to the east-southeast (Hawaii is the youngest, while the seamounts to the west-northwest are oldest). Assuming the hot spot is stationary, and the entire chain of islands was formed by this hot spot, which direction is the Pacific plate moving?
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West-northwest
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A hot spot of long term active volcanism is:
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The Earth surface location of a large mantle plume
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Oceanic ridges are elevated compared to the surrounding
ocean floor because __________.
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Newly formed lithosphere is hotter and therefore less dense than the surrounding rocks and occupies more space
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Which technique for calculating when the Earth formed as a planet is the most accurate in determining a numerical age for the Earth?
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Analysis and measurement of the ratios of uranium and lead isotopes present in rocks.
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Which of the following geologic observations would indicate that a sandstone is younger than a granite?
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An unconformity surface between the granite and sandstone
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Which of the following best defines a mineral and a rock?
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In a mineral the constituent atoms are bonded in a regular, repetitive, internal structure; a rock is a lithified or consolidated aggregate of different mineral grains.
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Atoms of an element with an electrical charge are ____ and atoms of an element with different number of neutrons in the nucleus are ____ .
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ions; isotopes
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The difference between ionic and covalent bonds is _______.
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Ionic bonds are when atoms are attracted electrostatically due to positive and negative charges; covalent bonds are when atoms share the same electron(s)
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A sheet silicate mineral, with silica tetrahedra ions arranged in sheets will usually:
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Have good cleavage along the sheets
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The feldspars are an example of a mineral group with:
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3-dimensional array of silica tetrahedra.
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A mineral composed of iron (Fe) and oxygen would be:
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An ore mineral for iron
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A mineral is considered a gemstone if it:
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Has good color, reflects light well, is rare.
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Why do magmas rise toward Earth's surface?
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Magmas are mainly liquid and contain dissolved fluids such as water; most are less dense than the adjacent solid rock.
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How is magma produced from rising mantle rock along midocean ridges?
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Temperatures remain high as lowered pressures decrease melting temperatures.
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Which of the following describes best the difference between magma and lava?
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Upon eruption, magma becomes lava, the magma that flows out of the volcano
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Lava flows are typically finer grained than intrusive igneous rocks. Why?
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The extrusive magma cools quickly so the mineral grains do not have time to grow.
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Composite cone, high slope angle-volcanoes are characteristic of :
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Subduction zone andesitic volcanoes.
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Which of the following rocks is likely to have the most quartz within it and why?
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Granite; intrusive rock that formed from cooling of relatively high silica magma.
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Which one of the following shows the correct order of decreasing magma viscosity and silica content of magma (high viscosity on left, low viscosity on right)?
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rhyolite, andesite, basalt
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What is a difference between a caldera and a crater?
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A caldera is a large depression caused by collapse after a large-scale eruption, whereas a crater is a small, steepsided, volcanic depression bored out by an eruptive event.
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Which one of the following most accurately describes the volcanoes of the Hawaiian Islands?
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Shield volcanoes fed by a long-lived hot spot below the Pacific lithospheric plate.
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Which one of the following is a natural disaster?
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A landslide striking San Francisco. Not a hurricane, volcano, or earthquake.
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The principle of ___ states that the physical, chemical, and biological processes at work shaping the Earth today have also operated in the geologic past.
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Uniformitarianism
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What is the accepted age of the Earth?
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4.56 billion years
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___ was an important 18th century scientist who developed the idea of Uniformitarianism to explain the slow, steady changes responsible for shaping the Earth.
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James Hutton
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What percentage of the Earth is covered by oceans?
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71%
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What percentage of the Earth is covered by oceans?
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Energy exchanges b/w the surface and outer space, creating weather and climate. Protection from ultraviolet radiation and the intensity of the Sun. Providing air for respiratory processes in the biosphere.
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Which of the four spheres of Earth is the most extensive?
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Geosphere
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What is the date of the formation of the universe?
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13.7 billion years ago.
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What is the definition of differentiation?
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Separation of materials based on density.
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What property of the crust allowed it to form as the exterior of the Earth?
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Materials that make up the crust are less dense and rose to the top.
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What provides us with the most information about the interior of the Earth?
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Seismic energy waves
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If the temperature in the Earth generally increases with depth, how is it possible that the Inner Core is a solid?
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The pressures in the core are immense and keep it in a solid state in spite of the temperature.
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Which layer of the Earth is the thinnest?
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Crust
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Which layer of the Earth is the thickest?
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Mantle
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What is the definition of the asthenosphere?
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A soft, low-velocity layer in the Upper Mantle.
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The ___ is a layer of liquid nickel and iron believed to be responsible for generating the Earth's magnetic field.
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Outer Core
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A ___ is a part of the craton that is covered by a thin veneer of sedimentary rocks.
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Platform
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In what two areas are the youngest mountain ranges found today?
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The Circum-Pacific belt and Southern Europe/Asia
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Historical geology describes geological processes that operate on the Earth.
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FALSE.
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Geologic hazards are natural processes.
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TRUE. Natural hazards result from natural Earth processes.
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Before a hypothesis can become an accepted part of scientific knowledge, it must pass objective testing and analysis.
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TRUE.
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A hypothesis can never be changed or modified.
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FALSE
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The majority of the hydrosphere is found in the atmosphere in the form of water vapor.
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FALSE
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The four spheres on Earth operate independently from each other.
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FALSE. The 4 major systems of Earth are the geosphere, hydrosphere, atmosphere, and biosphere.
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Both energy and matter will flow in and out of an open system.
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TRUE
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The interior of the Earth is divided into roughly spherical layers separated by density.
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TRUE. Earth formed from the accumulation of dust and gas, and multiple collisions of smaller planetary bodies.
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The lithosphere is the layer in the interior of the Earth that is just below the crust.
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FALSE
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External processes driven by solar energy can create the materials necessary for sedimentary rocks.
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FALSE
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The craton is the interior of a continental mass that has been undisturbed for the last 1 billion years.
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FALSE
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___ is the doctrine that describes how the Earth was shaped by a series of great catastrophes over a short period of time.
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Catastrophism
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What was the source for the early atmosphere?
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Differentiation of materials in the early Earth and the process of degassing led to the early atmosphere.
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Earth's spheres
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Hydrosphere - water portion
Biosphere - all life on Earth
Atmosphere - gaseous envelope around the planet
Geosphere - the solid earth
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Events leading up to the formation of the early Earth in order.
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1. Rapid expansion of stellar matter
2. Formation of solar nebula
3. Nuclear fission lights up Sun
4. Formation of proto-planets
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Igneous Rocks
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Rocks that form from the crystallization of molten material. Examples: Granite, Gabbro, Rhyolite, Basalt
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Sedimentary Rocks
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Rocks that form from pre-existing materials going through lithification. Examples: Limestone, Conglomerate, Arkose, Dolomite
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Metamorphic Rocks
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Rocks that form when a pre-existing rock is altered due to heat and pressure. Examples: Slate, Schist, Quartzite, Phyllite
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Which scientist developed the idea of Continental Drift?
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Alfred Wegener. He also proposed the super-continent Pangaea.
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Although the jigsaw-puzzle fit of the southern continents was noted, opponents of Continental Drift argued that, even if continental displacement had occurred, a good fit between the continents today would be unlikely. What geological evidence did they cite to support this claim?
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Wave erosion and coastal deposition have changed the shape of the continents
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When the continents were assembled and mountain ranges were matched up, mountains in Scandinavia and the British Isles matched up perfectly with which North American mountain range?
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Appalachian Mountains
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The lithosphere is composed of material from the ________ and the rigid part of the ________.
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Crust; Upper Mantle
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Which plate boundary accounts for the smallest percentage of all plate boundaries on the surface of the Earth?
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Transform Boundaries
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Continental crust is mainly composed of ________ whereas oceanic crust is mainly composed of ________.
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Granite; Basalt
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Why are the mid-ocean ridges higher in elevation than the surrounding ocean floor?
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Warmer material near the ridge is less dense, so floats higher on the mantle
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At a ________, one colliding plate will be forced beneath another because of differences in density.
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Subduction Zone
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How will the age and temperature of the subducting plate affect its angle of descent?
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Younger and warmer plates will have a shallow angle of descent
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A ________ is a geographic low marking the location where oceanic lithosphere descends into the mantle.
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Deep-Ocean Trench
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Which type of convergence will result in a continental volcanic arc?
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Oceanic-Continental
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Which type of convergence will result in a volcanic island arc?
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Oceanic-Oceanic
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Where are the majority of transform faults located?
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On the ocean floor offsetting segments of oceanic ridge
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What is a mantle plume?
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An upwelling of hot material from the Earth's interior that is cylindrical in shape
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________ is when iron particles in lavas align their magnetic fields with magnetic north, preserving a record of that pole's location at that moment in time.
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Paleomagnetism
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Where is the top of the asthenosphere is closest to Earth's surface?
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Along a mid-ocean ridge
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What two pieces of information would researchers need to have in order to calculate the rate of plate motion for seafloor spreading?
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Distance from the rift and age of seafloor sample
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How can the orientation of transform faults provide information about the direction of plate motion?
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Transform faults are parallel to the direction of plate motion
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What generates the heat necessary for convection in the Earth?
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Decay of radioactive materials
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________ is when cold oceanic lithosphere are more dense than the underlying warm lithosphere.
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Slab Pull
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In which layer of the Earth does the convection necessary for plate motion occur?
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Outer Core
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The majority of divergent plate boundaries are associated with oceanic ridges.
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TRUE
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An oceanic plate that has been permeated by water before subduction will melt at a lower temperature than a "dry" oceanic plate.
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TRUE
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Which is denser: Oceanic lithosphere or continental lithosphere?
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Oceanic lithosphere
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Analyze and explain how the respective temperatures of the lithosphere and asthenosphere affect those layers' rigidities and responses when force is applied.
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The lithosphere is cooler and more rigid, so will bend or break when force is applied. The asthenosphere is warmer and more pliable, so will flow when force it applied.
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_______ is the name of the process by which new seafloor is generated at mid-ocean ridges.
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Seafloor Spreading
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Tectonic boundary
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Convergent - crust is being destroyed (compression affecting it)
Divergent - crust is being created (tension affecting it)
Transform - crust is being conserved (shear affecting it)
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Chapter 10