SCIN Study 2 – Flashcards

What was the main view how the world worked geologically prior to the 1960s? A) It was generally believed that the earth was flat. B) It was generally believed that mountains were produced by vertical forces. C) It was generally believed that continents and oceans moved. D) It was generally believed that oceans formed as a result of meteorite impacts

In Wegener's time, scientists thought that the occurrence of fossils of the same organism in two different, disconnected continents was proof that ________. A) there had once been land bridges separating the continents B) the weather patterns had changed over time such that some organisms could be blown by the wind from one place to another. C) there were icebergs in the Atlantic Ocean that could carry organisms from Africa to South America D) birds flew between the continents and carried the organisms with them.

Wegener's work is a good demonstration of the scientific method because ________. A) he was right, but no one believed him B) his hypothesis passed all of the scientific testing to become a theory C) his hypothesis did not pass all of the scientific tests to become a theory D) he was wrong, and as a result, no one believed him

Which of the following statements apply to the asthenosphere, but not the lithosphere? A) zone in the upper mantle that deforms by plastic flowage B) cool, rigid layer of crust and upper mantle that forms the tectonic plates C) deforms mainly by brittle fracturing and faulting D) partial melting of rising granitic plumes produces huge volumes of basaltic magma

All of the earth's ocean basins are ________. A) less than 2 million years old B) less than 20 million years old C) less than 200 million years old D) less than 2000 million years old

Volcanoes form above subduction zones because ________. A) the subducting lithosphere melts as it descends and the magma rises to form volcanoes B) the lithosphere thickens above the subducting lithosphere and causes volcanoes to form C) the asthenosphere is displaced by the subducting lithosphere and rises to the surface to form volcanoes D) water is squeezed out of the subducting slab and the water triggers melting of the overlying asthenosphere

The San Andreas fault zone in California is an example of ________. A) a transform plate boundary B) a continental rift C) a divergent plate boundary D) an ocean-continent collision

Which ocean formed as a direct result of the breakup of Pangaea? A) Pacific B) Arctic C) Mediterranean D) Atlantic

Which of the following is considered the most important driving factor for Plate Tectonics? A) layer cake B) slab pull C) whole mantle D) ridge push

Alfred Wegener developed the theory of Plate Tectonics.

Wegener suggested the thick continents moved through the thinner ocean crust.

Oceanic crust has a mafic composition and therefore is denser than continental crust.

Continental rocks do not rift because they are too thick

Earth's radius and surface area are slowly increasing to accommodate the new oceanic crust being formed at mid-ocean ridges

The oldest rocks of the oceanic crust are found in deep ocean trenches far away from active, mid-ocean ridges

Major earthquakes are often followed by somewhat smaller events known as ________. A) aftershocks B) foreshocks C) tremors D) hyposhocks

The position on Earth's surface directly above the earthquake source is called the ________. A) seismic zone B) inertial point C) focus D) epicenter

Which one of the following statements is correct? A) P waves travel through solids; S waves do not. B) P and S waves travel through liquids, but P waves do not travel through solids. C) P and S waves travel through solids and P waves travel through liquids. D) P and S waves travel through liquids, but S waves do not travel through solids.

One measurement that is widely used to determine how far the focus of an earthquake is from the seismograph where it is recorded is ________. A) the amplitude of the P-wave B) the amplitude of the S-wave C) the difference in amplitude between the P and the S wave D) the difference in travel time between the P and the S wave

The 2011 earthquake and tsunami in Japan killed approximately 21,000 people while the 2010 earthquake in Haiti killed approximately 316,000 people because ________. A) the earthquake in Haiti was a larger magnitude (released more energy) than the one in Japan B) the earthquake in Haiti generated a very large tsunami that killed most of the people C) the construction methods in Haiti were not as good as those used in Japan D) the population of Haiti was much greater than that of northern Japan where the earthquake occurred E) All of the above were factors.

Earthquakes with a very deep focus are usually located along ________. A) a divergent plate boundary such as the Mid-Atlantic Ridge B) a transform boundary such as the San Andreas C) a hot spot chain such as the Hawaiian Islands D) a convergent boundary such as the Peru-Chile trench

Seismic gaps are places where scientists think that ________. A) faults are storing elastic strain B) faults are storing stress C) faults are creeping smoothly D) earthquakes are unlikely to occur

The earth's major layers formed because ________. A) the chemical composition of the solar nebula changed over time B) the earth was heated after its formation resulting in melting and redistribution of major chemical compositions C) radioactive decay caused materials to change over time and resulted in the layering D) the earth's mantle grew like a crystal forming around the earth's core but the crust was exposed to space and stayed more like the original material

Oceanic crust is composed primarily of ________. A) granite B) basalt C) sandstone D) andesite

Large earthquakes almost always produce new faults because the old faults tend to "heal" in the long time that separates most large earthquakes

A magnitude scale is a measure of the energy released. It does not measure the extent of building damage or loss of life.

During the Alaskan earthquake of 1964, the buildings that survived the best were made of wood

The ocean ridge systems that make up the major divergent plate boundaries are a source of frequent large earthquakes and tsunamis.

A few days before a major earthquake in China, one village in the area reported the streets were filled with migrating toads that might have indicated the impending event.

Oceanic crust is less dense than continental crust

Considering the history of Mt. St. Helens and Kilauea volcanoes and your knowledge of volcano types in different tectonic settings, if you had to live on a volcano, which of the following would you choose if safety was your only concern? A) Mt. Spurr in the Aleutian volcanic arc B) Mt Fujiyama in the Japanese island arc C) Mt. Rainier in the Cascades just north of Mt. St. Helens D) Mauna Loa in Hawaii, on the Big Island of Hawaii near Kilauea

________ tend to increase the explosive potential of a magma body beneath a volcano. A) High viscosity and dissolved gas B) High viscosity and low dissolved gas content C) Low silica content and low viscosity D) Low viscosity and low dissolved gas content

Volcanic bombs originate ________. A) as laser-guided, granite blocks launched from a supersonic jet B) as blocks of volcanic rock ejected from an erupting volcanic crater C) as erupted magma blobs that partly congeal before falling to the ground D) as ash particles that join together in the eruptive plume and fall as cobble-sized objects

The average composition of rocks comprising a large composite cone or stratovolcano is similar to a(n) ________ magma. A) basaltic B) andesitic C) ultramafic D) rhyolitic

Cinder cones ________. A) have very steep slopes B) are usually less than 300 meters (1000 feet) high C) consist largely of pyroclastics D) all of these

Mount Pelée on the island of Martinique killed thousands of people in ________. A) a pyroclastic flow, also called a Nuée Ardent B) a caldera collapse C) an ash fall that smothered the people living there D) a cinder cone eruption

The Columbia Plateau in the northwestern United States is an excellent example of ________. A) silica-rich lava flows B) pyroclastic flow deposits C) flood basalts D) an eroded shield volcano

A ________ is the largest discordant body of intrusive, igneous rock. A) lopolith B) laccolith C) pluton D) batholith

In what plate tectonic setting are magmas generated predominantly by fluids fluxing the melting process by decreasing melting temperature? A) hot spots B) convergent plate margins C) transform faults D) spreading ridges

When magma rises toward the surface, pressure decreases can lead to release of dissolved gases in a magma with a volume increase that can produce an explosion.

Pillow lavas are basaltic magmas extruded as piles of bombs that accumulate in piles of rocks that look like a pile of pillows

Shield volcanos have extensive deposits of pyroclastic rocks

Volcanoes have no significant impact on weather and climate.

Many magmas are generated when solid rocks are carried to higher levels in the earth by flow and partially melted by decompression melting

The main mechanism for melting at spreading ridges is decompression melting of ultramafic mantle rock.

The concepts of "stress" and "strain" are related because ________. A) "strain" causes "stress" B) "stress" causes "strain" C) compressional "stress" causes a convergent plate boundary to form D) compressional "strain" causes a convergent plate boundary to form

The higher the temperature, the more likely it is that a rock will deform ________. A) ductilely B) brittlely C) elastically D) shearingly

Large circular downwarped structures are called ________. A) anticlines B) synclines C) basins D) domes

In a(n) ________ fault, the hanging wall block moves up with respect to the footwall block. A) normal B) strike slip C) reverse D) abnormal

What is the modern theory for orogenesis? A) geosynclinal theory B) shrinking earth model C) expanding earth theory D) plate tectonics theory

A good example of a present-day, passive continental margin is the ________. A) east coast of North America B) west coast of South America C) east coast of the Japanese Islands D) north flank of the East Pacific Rise

Island arc systems now on the Tibet plateau record subduction prior to the collision of India with Eurasia. Geologists would map these pre-collisional arc rocks as ________. A) hot spot tracks B) terranes C) rift zones D) pre-collisional transform zones

The Tibetan plateau is high above sea level because ________. A) there are many active faults across Tibet that produce internal crustal thickening and uplift B) the extrusion of East Asia has produced structures that thicken the crust under Tibet, producing regional uplift C) a giant fault beneath Tibet raises it up relative to adjacent areas D) crustal thickening over millions of years has produced a thick crust that stands high due to Isostasy

In the interior of continents the earth's crust is typically about 40km thick and the elevation is above sea level. In an area where the crust is 20km thick, isostasy would suggest the elevation in this area would be ________ unless the density changes from one area to the other. A) below sea level B) near sea level C) slightly above sea level D) high mountains

When the differential stress exceeds the strength of the material, the material will begin to undergo elastic strain

The hinge of a fold must lie within the axial plane of the fold.

Subduction only occurs when oceanic rocks are forced beneath a continent.

Subduction produces mountains because subduction zones are the upwelling zones of mantle convection, which lifts the earth's surface to form mountains

Terrane accretion generally occurs along a convergent boundary between a continental plate and an oceanic plate.

Changes in the shape of a rock body in response to a differential stress is called deformation

Who is credited with formulating the doctrine of uniformitarianism? A) Hutton B) Lyell C) Aristotle Hutton D) Playfair

The principle of superposition which states that in undeformed rocks, the younger rocks will be on top of older rocks, is particularly important because ________. A) it supports the laws of gravity which indicate that rocks must be deposited on something that already exists B) it showed that the interior of the earth is not growing outward C) it provided an order for assembling the relative ages of various rock layers D) it proved that life evolved by putting fossils in a logical order

In the late 1800's various principles (original horizontality, inclusions, cross cutting relations, etc. arête) were established and used to ________. A) determine the age of the earth B) organize the order in which events occurred on earth C) determine the age of events on the earth D) prove that evolution was a valid theory that could explain many geologic observations

Petrified wood is an example of a fossil formed by ________. A) permineralization replacing original cellulose of the wood B) cast and mold preservation C) direct preservation D) trace fossil imprints

You go for a hike across an outcropping of sandstone and you see large footprints in the sandstone. You have just found ________. A) Bigfoot B) a trace fossil C) proof of an ancient flood D) a mold

A geologist observes abundant fossils of a distinctive trilobite species in a shale, but this trilobite disappears as she walks through the shale. In younger rocks, just above the horizon where the fossil disappears another species of trilobite becomes the prominent fossil in similar shales. Which conclusion is most logical for this observation? A) The organisms whose remains form the first fossil moved from the area for unknown reasons. B) A hurricane or other catastrophe killed all of the early species so the other species could move in. C) The second, trilobite group in the upper section went extinct where the change in fossils is seen. D) The first trilobite species went extinct and its ecological niche was occupied by another species, which may have evolved from the first.

The ratio of parent to daughter isotopes in a radioactive decay process is 0.40. How many half-lives have elapsed since the material was 100% parent atoms? A) less than l B) more than 3 C) between l and 2 D) between 2 and 3

Which of the following denotes the divisions of the geologic time scale in correct order of decreasing lengths of time beginning with the longest time interval and ending with the shortest? A) eon, era, epoch, period B) era, period, epoch, eon C) eon, epoch, period, era D) eon, era, period, epoch

In the last few years improvements in technology have allowed geologists to date single grains of some minerals in rocks. A geologist separates 5 grains of the mineral zircon, which can be dated by the Uranium-lead method, and the crystal retains parent and daughter through weathering, erosion, and deposition. Thus, dating each mineral grain only gives the age of the source rock that was eroded, to produce that sand, from which the zircon grain is derived. The 5 grains yield ages of 160, 110, 2020, 66, and 162 million years. What do these ages tell you about the age of the sedimentary strata? A) They are Precambrian rocks, older than 2020 million years. B) They are between 160 and 162 million years. C) They are younger than 66 million years. D) There are no age constraints from this data; sedimentary rocks cannot be dated by geochronology

Radiometric data was the key to modern geology replacing catastrophism

An unconformity involving older metamorphic rocks and younger sedimentary strata is termed a nonconformity

After three half-lives, one-ninth of an original radioactive parent isotope remains, and eight-ninths has decayed into the daughter isotope

The percentage of radioactive atoms that decay during one half-life is always the same

All of geologic time prior to the beginning of the Paleozoic era is termed the Phanerozoic eon

Most sedimentary rocks are readily dated by radiometric methods

Why is it important that we have a rigid lithosphere overlying a weak asthenosphere? A) If we did not have the rigid lithosphere and weak asthenosphere, the earth would not have plate tectonics and would be covered entirely by water. B) If we did not have the rigid lithosphere and weak asthenosphere, the atmosphere would be very different with either too much ammonia and methane or too little oxygen and water. C) If we did not have the rigid lithosphere and weak asthenosphere, we would be bombarded by cosmic rays that would strip away our atmosphere. D) If we did not have the rigid lithosphere and weak asthenosphere, we would be bombarded by meteorites and we would not be able to hold the moon in orbit

Which of the following was an important factor in determining the different parts of the solar system where the small rocky planets formed versus where the light, gaseous planets formed? A) density B) viscosity C) temperature D) gravity E) velocity

The large size of insects and amphibians during the Pennsylvanian period has been suggested to be due to ________. A) a lack of predators for early land forms B) an excess of sunlight and water during that time C) an excess of oxygen during that time D) a decrease in methane in the atmosphere during that time E) the emergence of a super continent that allowed greater areas for animals to evolve

Continental crust is formed by ________. A) melting and differentiation of oceanic crust at subduction zones B) partial melting of mantle rocks C) plumes of hot igneous material that rise from the core-mantle boundary to form hot spots D) the original planetary accretion that also led to the formation of the earth's other layers E) recycling of material in giant lava lakes in the early earth history

The Laramide Orogeny at the end of the Mesozoic produced ________. A) the Appalachian Mountains in the eastern U.S. B) the Ural Mountains in Russia C) the Alps in Europe D) the Rocky Mountains in the western U.S. E) the Himalayan Mountains in Asia

Scientists have found evidence that life existed at least 3.5 billion years ago ________. A) in northern Siberia B) on the Gulf Coast C) throughout North and South America D) in Kenya E) in several locations around the world

The largest mass extinction in the Phanerozoic occurred in the ________. A) Jurassic B) Devonian C) Permian D) Cambrian E) Miocene

Which of the following is modern descendant of the Gymnosperm? A) pine trees B) tulips C) turkeys D) crocodiles E) sharks

Mammals became the dominant land animals during the ________ era. A) Pleistocene B) Cenozoic C) Cretaceous D) Mesozoic E) Paleozoic

The decay of radioactive atoms, coupled with heat released by colliding particles, produced at least some melting of Earth's early interior

Earth's original atmosphere, several billion years ago, was similar to the present atmosphere.

Well preserved remains of many tiny organisms extend the record of life back beyond 5 billion years.

Volcanic activity was common in western North America during much of Cenozoic time

The first true terrestrial land animals were the mammals.

The Cenozoic era is the age of mammals.