GEOL 15OO: EXAM 1
205 Cards in this Set
| Front | Back |
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The _____ division of the geologic time scale is an era of the Phanerozoic eon.
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Paleozoic
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The currently accepted age of Earth is _____ years.
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4.6 billion
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Metamorphic rocks are created by _____.
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temperatures hot enough to change the rock in the solid state without melting it
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_____ was an important 18th-century English geologist and proponent of Uniformitarianism.
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James Hutton
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The _____ refers to the sum total of all life on Earth.
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biosphere
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The relatively stable interior portion of a continent is known as a _____.
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craton
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The asthenosphere is a relatively cool and rigid shell that overlies the lithosphere.
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false
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The composition of the core of Earth is thought to be _____.
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solid iron-nickel alloy
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According to the rock cycle, any type of rock (igneous, sedimentary, or metamorphic) may be transformed into another type of rock, given enough time.
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True
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Internally, the Earth consists of spherical shells with different compositions and densities.
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True
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________, a popular natural philosophy of the 17th and early 18th centuries, was based on a firm belief in a very short geologic history for Earth.
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Catastrophism
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The doctrine of uniformitarianism implies that the current forces and processes shaping the Earth have been operating for a very long time.
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True
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________ is the process by which rocks breakdown in place to produce soils and sediments.
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Weathering
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The _____ is the thinnest layer of the Earth.
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crust
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Musch of our modeling Earth's interior comes from the study of seismic or earthquake waves.
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True
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_____ rocks always originate at the surface of solid Earth.
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Sedimentary
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In correct order from the center outward, Earth includes which units?
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inner core, outer core, mantle, crust
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Which of the following best describes the fundamental concept of superposition?
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any sedimentary deposit accumulates on top of older rock or sediment layers
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The law os superposition applies primarily to sedimentary rocks and lava flows.
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True
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A _____ is a well-tested and widely accepted view that best explains certain scientific observations.
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theory
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A scientific theory is a tentative or untested explanation that is proposed to explain scientific observations.
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False
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What is relative age dating?
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the order of events, but not their exact ages in years
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The asthenosphere is actually a part of the _____ of the Earth.
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mantle
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_____ rocks form by crystallization and consolidation of molten magma.
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Igneous
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Which of these statements is most consistent with the law of uniformitarianism?
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"The present is the key to the past."
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What does the Law of Uniformitarianism say?
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the laws governing geology today also governed it in the past
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The _____ is thought to be a liquid, metallic region in the Earth's interior.
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outer core
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Active mountain belts are most likely to be found _____.
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along the margins of continents
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_____ is often paraphrased as "the present is the key to the past."
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uniformitarianism
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Which sphere does the crust of Earth belong to?
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geosphere
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Sedimentary rocks may weather to igneous rocks.
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False
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Magmas crystallize to form igneous rocks.
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True
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Igneous rocks can undergo metamorphism.
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True
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Metamorphic rocks may melt into magma.
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True
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According to the nebular hypothesis, all of the bodies in the universe evolved from a rotating cloud of cases and dust about 5 billion years.
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False
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The _____ forms relatively cool, brittle plates of plate tectonics.
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lithosphere
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The _____ proposes that the bodies of our solar system formed at essentially the same time from a rotating cloud of gases and dust.
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Nebular hypothesis
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Compared to the age of the Earth accepted as correct today, how did the 17th and 18th century proponents of catastrophism envision the Earth's age?
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They believed Earth to be much younger than current estimates
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When a researcher publishes research in a national journal, what part of the scientific method is he or she most likely involved with?
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a hypothesis
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Igneous rocks are produced largely by the deposition and consolidation of surface materials like sand and mud.
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False
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The _____ is not a part of the Earth's physical environment.
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astrosphere
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All of the following are possible steps of scientific investigation except for _____.
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assumption of conclusions without prior experimentation or observation
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The lithosphere and asthenosphere are both layers of Earth defined by their composition.
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True
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A transform plate boundary is characterized by _____.
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a deep, vertical fault along which two plates slide past one another in opposite directions
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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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The oldest rocks on the seafloor are much younger than the oldest rocks on the continents.
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true
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Earth's magnetic field reverses over geologic time.
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True
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A rock changes its magnetic field direction over geologic time as Earth's magnetic field changes.
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False
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Magnetic stripes on the ocean floor provide weak evidence for seafloor spreading.
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False
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Geomagnetic reversals cause the movement of the tectonic plates.
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false
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The volcanoes and deep valleys of East Africa are related to a _____.
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continental rift along which parts of the African continent are beginning to slowly separate.
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Deep ocean trenches are evidence for _____.
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sinking of oceanic lithosphere into the mantle at a subduction zone
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The _____ is an example of an active, continent-continent collision.
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northward movement of India into Eurasia
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The _____ is a logical evolutionary analog of the African Rift Valleys ten million years from now.
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Red Sea
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The continental drive hypothesis was rejected primarily because Alfred Wegener could not ______.
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identify a mechanism capable of moving continents
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Linear, magnetic patterns associated with mid-ocean ridges are configured as _____.
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normal and reversed magnetized strips roughly parallel to the ridge
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Which one of the following is an important fundamental assumption underlying the plate tectonic theory?
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Earth's diameter has been essentially constant over time.
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Wegener's continental drift hypothesis was weakened because a viable mechanism for moving the continents was lacking.
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True
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Cooler, older, oceanic lithosphere sink into the mantle at _____.
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subduction zones along convergent plate boundaries
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Deep ocean trenches are formed by _____.
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the subduction of lithosphere into the asthenosphere
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The Himalayan Mountains are the tectonic product of a collision between Indian and Eurasia that began about 40 million years ago and still continues.
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True
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Earth's radius and surface area are slowly increasing to accommodate the new oceanic crust being formed at mid-oceanic ridges.
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False
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Mount St. Helens and the other Cascade volcanoes are ______.
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young, active volcanoes built on a continental margin about a sinking slab of oceanic lithosphere
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As the South Atlantic basin wides by seafloor spreading, Africa and South America are moving closer together.
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False
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Beneath Earth's lithosphere, the hotter, weaker zone known as the _____ allows for motion of Earth's rigid outer shell.
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asthenosphere
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Which of the following observations was included as evidence for Wegener's continental drift hypothesis?
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the jigsaw-puzzle fit of the continents
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Iceland is a good example of an island arc, formed from an oceanic-oceanic plate collision.
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False
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Pull-apart, rift zones are generally associated with _____.
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a divergent plate boundary
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The slowly increasing distance between South America and Africa is due to _____.
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seafloor spreading
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Old Faithful Geyser at Yellowstone National Park in the United States acquires its energy from a _____.
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hot spot
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Layered _____ exposed by erosion can be seen when looking at the Grand Canyon in the United States.
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sedimentary rock
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Australia is composed of relatively old and thick _____.
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continental crust
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The extremely deep ocean Marianas Trench is a result of _____.
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subduction
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_____ found in the Atlantic Ocean between North America and Europe is composed of dense and relatively young rock.
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seafloor crust
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The earthquakes that occur in Southern California generally occur above a _____.
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fault
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A typical rate of seafloor spreading in the Atlantic Ocean is _____.
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2 centimeters per year
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The Aleutian Islands occur at a _____.
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convergent boundary on a volcanic arc above a northward-subducting Pacific plate
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The rate of seafloor spreading is, on the average, about one meter per year.
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False
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Which boundary is characterized as a long, linear rise in the seafloor, with shallow earthquakes and volcanic activity found along its length?
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divergent boundary
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The Hawaiian Islands were formed as a result of _____.
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a mantle plume
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Which of the following lithospheric plates is not included among the seven largest?
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the Philippine plate
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Earth's lithospheric plates are composed of crust and which of the following layers?
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the outermost portion of the mantle
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In studies of rock obtained from ocean basis all over Earth, the oldest ages obtained are approximately 200 million years before the present. Why have no older oceanic rocks been discovered?
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Due to tectonic activity, rocks on the ocean floor are continually recycled
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Currently the Juan de Fuca plate is interacting with the North American plate where inland volcanoes and deep focus earthquakes are occuring. What type of plate boundary is this?
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a convergent plate boundary
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The volcanoes of Hawaii are localized above a deep mantle hot spot; they are not part of the East Pacific oceanic ridge.
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True
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The oldest rocks of the oceanic crust are found in deep ocean trenches far away from active, mid-ocean ridges.
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True
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Seafloor spreading rates can be estimated if the geologic ages of the magnetic field reversals are independently known.
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True
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New oceanic crust and lithosphere are formed at _____.
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divergent boundaries by submarine eruptions and intrusions of basaltic magma
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The former, late Paleozoic super continent is known as _____.
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Pangaea
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The Atlantic Ocean basin is getting _____ in size because _____.
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larger; no subduction is taking place at the basin's perimeter
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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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The modern-day Red Sea is explained by plate tectonics theory because it is _____.
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a rift zone that may eventually open into a major ocean if Arabia and Africa continue to separate
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A very long-lived magma source located deep in the mantle is called a _____.
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hot spot
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In general, rocks of the continental crust are less dense than rocks of the oceanic crust.
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True
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During various times in the geologic past, the polarity of Earth's magnetic field has been reversed.
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True
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All of the following are evidence supporting the theory of plate tectonics except for _____.
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changes in the Moon's orbit due to shifting plates
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In the early part of the 20th century, _____ argued forcefully for continental drift.
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Alfred Wegener
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Which of the following is one of the remarkable realizations associated with the discovery of seafloor spreading?
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the crust of the oceans is very young relative to the age of the continental crust.
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Deep-oceanic trenches are must abundant around the rim of the ____ ocean basin.
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Pacific
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Which of the following statements apply to the asthenosphere, but not the lithosphere?
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zone in the upper mantle that deforms by plastic flowage
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The strong tendency of certain minerals to break along smooth, parallel planes known as ____
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cleavage
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Diamond and Quartz are both minerals composed of a single element
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False
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All atoms of the same element have the same atomic structure
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True
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The ion at the center of a silicate tetrahedron is surrounded by____
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4 oxygen ions
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In a silicon-oxygen structural unit, silicon atoms occupy corners of the tetrahedron
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False
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Which group of minerals are the most abundant in the Earth's crust?
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silicates
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Atoms of the same element, zinc for example, have the same number of___
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protons in the nucleus
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Which of the following minerals is a ferromagnesian silicate?
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Hornblende
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Which one of the following is a sodium and calcium feldspar with twinning striations?
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plagioclase
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Hornblende and other amphiboles have what type of silicate structure?
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Double Chains
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Which one of the following describes a mineral's response to mechanical impact?
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Cleavage
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Which is an accurate description of ionic bonding?
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Atoms of different elements, having gained or lost electrons, form negative and positive ions that are bonded together by attractive forces between ions with opposite charges.
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Which mineral is composed of silicon dioxide (SiO2)?
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Quartz
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Two isotopes differ from one another because they have___
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Different numbers of Neutrons
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A group of the same type of atoms is called?
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An element
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Ferromagnesian silicate minerals contain some magnesium and/or iron
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True
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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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Why is sugar NOT considered a mineral?
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It is an organic compound.
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Graphite and diamond have the same chemical compositions and different crystalline structures.
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True
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Which of the following describes the light reflecting and transmission characteristics of a mineral?
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luster
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Calcite and halite react with dilute acids to release carbon dioxide.
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False
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Which mineral is easily soluble in water at room temperature conditions?
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halite
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Crystallization can occur _______.
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with temperature changes
from biological processes
from solutions in water
All of the above can cause crystallization.
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How do the electrons behave in a mineral with metallic bonding?
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They can move relatively easily from atom to atom inside the mineral.
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Which carbonate mineral reacts readily with cool, dilute hydrochloric acid to produce visible bubbles of carbon dioxide gas?
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calcite
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Which of the following minerals is a silicate?
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muscovite
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An atom's mass number is 13 and its atomic number is 6. How many neutrons are in its nucleus?
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7
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Calcite and dolomite are both carbonate minerals.
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True
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Which of the following will react readily with acids such as hydrochloric?
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calcite
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Electrically neutral atoms have equal numbers of electrons and protons.
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True
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What mineral is the hardest known substance in nature?
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diamond
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Ruby and sapphire are red and blue forms of the mineral ________.
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corundum
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Minerals such as biotite are dark because of their _______.
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iron content
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Which the following denotes the massive, positively charged, nuclear particles?
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protons
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The micas, biotite and muscovite, both exhibit one direction of cleavage.
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True
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Which one of the following is a typical product of weathering?
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clays
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Isotopes of the same element have the same mass number.
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False
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Which one of the following mineral groups exhibits a sheet-like silicate structure?
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clays
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Which of the following minerals is in the mineral group known as mica?
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muscovite
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The mineral quartz is an example of a _______.
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three-dimensional framework silicate
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What is the name given to an atom that gains or loses electrons in a chemical reaction?
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ion
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Which one of the following is not true for minerals?
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They can be a liquid, solid, or gas.
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A cubic centimeter of quartz, olivine, and gold weigh 2.5, 3.0, and 19.8 grams respectively. This indicates that ________.
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gold has a higher density and specific gravity than quartz and olivine
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Positive ions are atoms that have gained electrons during a chemical reaction.
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False
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Rocks are aggregates of one or more minerals.
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True
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Which of the following best characterizes ferromagnesian silicates?
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They are black to dark-green, silicate minerals containing iron and magnesium.
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In which type of chemical bonding are electrons shared between adjacent atoms?
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covalent
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All silicate minerals contain which two elements?
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silicon, oxygen
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An ion with a surplus of electrons _____.
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is negatively charged
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What is the name of dark-colored mica?
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biotite
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We are now living in the Mesozoic era.
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False
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One group of reptiles, exemplified by the fossil Archaeopteryx, led to the evolution of ________.
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birds
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Which era is sometimes called the "age of the dinosaurs"?
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Mesozoic
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The first true terrestrial animals were the ________.
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reptiles
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Many reptile groups became extinct at the close of the Cenozoic Era.
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False
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How did Earth's first enduring atmosphere begin?
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from volcanic outgassing
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The most common Precambrian fossils are ________, layered mounds of calcium carbonate.
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none of the above
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The beginning of the Precambrian Era is marked by the appearance of the first life forms with hard parts.
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False
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Which era is sometimes called the "age of dinosaurs"?
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Mesozoic
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The time of the great extinction that took place at the end of the Mesozoic Era is called the ________ or KT boundary.
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Cretaceous-Tertiary
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The age of Earth is about ________.
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4.5 billion years
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By the ________ period, large tropical swamps extended across North America, eventually becoming the vast coal deposits of today.
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Pennsylvanian
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Mammals replaced reptiles as the dominant land animals in the Cenozoic Era.
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True
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Mammals became the dominant land animals during the ________ era.
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Cenozoic
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The theory for the origin of the solar system is known as the ________ hypothesis.
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nebular
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The major source of free oxygen in the atmosphere is from ________.
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green plants
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Which period is known as the "age of trilobites"?
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Cambrian
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Which period is known as the "age of fishes"?
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Devonian
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Earth's original atmosphere, several billion years ago, was similar to the present atmosphere.
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False
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Probably the single most characteristic feature of the Precambrian is its great abundance of fossil evidence.
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False
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The era of "ancient life" is the ________ era.
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none of the above
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Fossil fuels are abundant in Precambrian rocks.
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False
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The first primitive organisms to inhabit Earth came into existence roughly _____ years ago.
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3.8 billion
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Which of the following is an essential characteristic of an index fossil?
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the organism only lived for a short period of geologic time
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The ________ is the idea or concept that ancient life forms succeeded each other in a definite, evolutionary pattern and that the contained assemblage of fossils can determine geologic ages of strata?
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principle of faunal succession
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By studying rocks, especially _____, geologists can unravel the complexities of past environments.
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sedimentary rocks
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________ is an erosional contact between tilted, older strata below and horizontal, younger strata above.
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An angular unconformity
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What of the following refers to the investigative process by which geologists identify and match sedimentary strata and other rocks of the same ages in different areas?
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correlation
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Consider the names of the eras in the geologic time scale. What is meant by "zoic"?
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life; living things
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The task of matching rocks of similar age in different regions is called _____.
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correlation
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What fundamental concept states that in a horizontal sequence of conformable sedimentary strata, each higher bed is younger than the bed below it?
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law of superposition
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Assume that man's recorded history can be stretched back to 4600 years before the present. This is approximately what fraction of geologic time?
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one millionth
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The geologic time scale was devised before numerical dating using radioactivity was invented.
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True
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Which concept could be used to relatively age date a fault?
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cross-cutting
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Sandstone strata and a mass of granite are observed to be in contact. Which of the following statements is correct geologically?
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The granite is older if the sandstone contains pebbles of the granite.
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The term Mesozoic refers to life forms intermediate in complexity between early and much later, more modern-looking life forms.
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True
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The half-life of carbon-14 is about 6000 years. Assume that a sample of charcoal is formed by burning of living wood 15,000 years ago. How much of the original carbon-14 would remain today?
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between one-fourth and one-eighth
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Which of the following geologic observations would not bear directly on working out the sequence of geologic events in an area?
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the feldspar and quartz contents of a granite
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The process in which atomic nuclei spontaneously break apart is called _____.
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radioactivity
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Which of the following best characterizes an angular unconformity?
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Tilted strata lie below the unconformity; bedding in younger strata above is parallel to the unconformity
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What two special circumstances are necessary in the preservation of organisms as fossils?
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rapid burial and possession of hard parts
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Rapid burial and possession of hard parts are necessary conditions for the preservation of plant or animal remains as fossils.
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True
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Visualize five, horizontal, sedimentary strata exposed in a cliff or canyon wall identified by consecutive numbers, 1 being the lowest bed and 5 being the highest. Which of the following statements concerning the strata are true?
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beds 1 and 3 are older than bed 4
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Carbon-14 is produced by cosmic rays reacting with nuclei of iron atoms in the Earth's core.
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False
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Strata above an angular unconformity were tilted before the older strata were eroded.
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False
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The term Paleozoic describes the era of ancient life forms.
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True
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What is the age of the Earth accepted by most scientists today?
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4.5 billion years
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Which two Paleozoic, geologic, time-scale periods used in North America are combined into the Carboniferous period in Europe and elsewhere?
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Mississippian; Pennsylvanian
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Numerical age dates based on radioactivity are very important for studying Proterozoic geologic history because fossils are rare or absent
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True
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The radioactive isotopes uranium-238, uranium-235, and thorium-232 eventually decay to different, stable, daughter isotopes of ________.
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lead
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Pebbles of granite in sandstone and conglomerate resting on the granite suggest that the granite intruded the sedimentary beds.
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False
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Complex, invertebrate, life forms are common as fossils beginning with marine strata of Cambrian age. How long ago did the Cambrian period begin?
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540 million years
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Which concept could be used to relatively age date an igneous intrusion?
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cross-cutting
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Which type of radioactive dating method is used to age date recent geologic events?
|
carbon-14
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The rare element iridium has been implicated in which "ancient health" crisis?
|
extinction of the dinosaurs at the end of the Cretaceous Period
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Landslides - Flashcards