GES 110 Quiz 10

What is the depth of the core-mantle boundary? 6370 km 2900 km 660 km 150 km

2900 km

How old is the earth? 6,000 years 4,600,000,000 years 100,000,000,000 years 5 x 106 years 65,000,000 years

4,600,000,000 years

The temperature in the earth's core is about 6000 degrees C 600 degrees C 60 degrees C we have no idea what the temperature is

6000 degrees C

Which of the following statements is NOT true? Pangaea is the name given to the "supercontinent" that formed around 300 million years ago by continental collision and that included all of the earth's major land masses Splitting of Pangaea began about 200 million years ago, leading to the formation of today's Atlantic Ocean Geologic evidence for the existence of Pangaea includes continental outlines that fit together like puzzle pieces as well as rock types and fossils that must have formed in the same place but are now on opposite sides of an ocean Alfred Wegener first suggested the idea of continental drift, but he had no supporting geologic or fossil evidence for his idea ALL of these statements are true

ALL of these statements are true

What of the following statements is true? Geologists believe that plate tectonics is driven by convection in the mantle, with upwelling of magma and spreading at divergent boundaries and sinking and subduction of older, cooler ocean floor at convergent boundaries Large parts of the continents are thought to have assembled over time by repeated accretion onto the continental margins of small crustal fragments like volcanic island arcs, oceanic plateaus and microcontinents that are rafted in across the ocean and plastered onto the continent along a subduction zone Ocean floor is both created and destroyed at plate boundaries, whereas continents tend to grow over time and are not destroyed All of the above are true

All of the above are true

What are the defining characteristics of a mineral? known chemical formula inorganic solid with known crystal structure any solid material of any composition any material of silicate composition whether in solid or molten form Answers 1 and 2 are both essential to the definition of a mineral

Answers 1 and 2 are both essential to the definition of a mineral

Which of the following physiographic provinces of the mid-Atlantic region is made up mostly of unconsolidated sediments deposited along a passive continental margin? Coastal Plain Piedmont Valley and Ridge Appalachian Plateau

Coastal Plain

How did the structures visible in this landscape form? (designs of blue and red arcs) Tensional stress associated with an episode of continental rifting Lateral offset along a transform or transcurrent fault boundary Gravitational instability causing wrinkling and rippling of the landscape associated with a massive outpouring of magma along a series of fissures Compressive stress caused by a continental collision along a convergent plate boundary

Compressive stress caused by a continental collision along a convergent plate boundary

All metamorphic rocks are foliated True False

False

All volcanoes occur at plate boundaries. True False

False

Salt deposits formed by evporation of water in a desert basin or shallow inland sea are considered clastic or detrital sediments. True False

False

Where would we be most likely to find an overthrust? Himalayas East African rift valley mid-ocean ridge along the San Andreas or North Anatolian fault

Himalayas

How do we know what the internal structure and composition of the earth's mantle and core look like? deep boreholes have allowed us to extract samples that are used to diagnose material properties including chemical composition and density ancient rocks left behind at the earth's surface from convection of deep mantle rocks and core material have been collected and analyzed P (compressive) and S (shear) waves that reverberate throughout the earth's interior have different speeds and travel times and change their paths as they move through materials of different properties; seismic wave recordings from locations all around the planet are used to build a model of earth's interior structure all of the above are true

P (compressive) and S (shear) waves that reverberate throughout the earth's interior have different speeds and travel times and change their paths as they move through materials of different properties; seismic wave recordings from locations all around the planet are used to build a model of earth's interior structure

When we look at the geologic time scale, we find that the first 87-88% of earth history falls within the time period known as the Cretaceous Paleozoic Precambrian Pleistocene Cenozoic

Precambrian

How is the Atlantic Ocean similar to or different from the Pacific Ocean? The Atlantic Ocean is bordered by active continental margins with steep relief, tectonic activity, earthquakes and volcanism whereas the Pacific Ocean is bordered mostly by passive continental margins with gentle slopes and low tectonic activity (except for the area near Japan) Both the Atlantic and the Pacific have an almost equal distribution of active and passive continental margins and areas of high and low relief and tectonic activity The Atlantic is bordered almost entirely by passive continental margins of low tectonic activity and has an almost symmetrical distribution of relief features centered on the mid-ocean ridge; whereas the Pacific is bordered mostly by active continental margins with steep relief, deep trenches, active chains of volcanoes, and high frequency of earthquakes The rocks on the floor of the Atlantic Ocean are much older than the rocks on the floor of the Pacific Ocean and therefore have much higher content of iron and magnesium and lower content of silicon and aluminum

The Atlantic is bordered almost entirely by passive continental margins of low tectonic activity and has an almost symmetrical distribution of relief features centered on the mid-ocean ridge; whereas the Pacific is bordered mostly by active continental margins with steep relief, deep trenches, active chains of volcanoes, and high frequency of earthquakes

Which of the boundaries listed in the previous question is associated with the largest extinction in the fossil record? at the boundary between the Precambrian and the Phanerozoic eons, about 540 million years ago at the boundary between the Tertiary and the Pleistocene epochs, about 2.6 million years ago at the boundary between the Permian and the Triassic, about 248 million years ago at the boundary between the Cretaceous and the Tertiary periods, about 65 million years ago

The boundary between the Permian and the Triassic, about 248 million years ago

Looking at the pair of rock samples below, choose the statement that best characterizes what you are looking at. (spotted vs clean) The rock on the left is felsic and the rock on the right is mafic. The rock on the left is plutonic and the rock on the right is volcanic. The rock on the left is metamorphic and the rock on the right is sedimentary. The rock on the left is basalt and the rock on the right is limestone. The rock on the left is volcanic and the rock on the right is plutonic

The rock on the left is plutonic and the rock on the right is volcanic.

Large parts of the western U.S. were created by accretion of microplates and exotic terranes that traveled across thousands of miles of ocean before reaching a subduction zone at the west edge of the continent and being added to the west coast. True False

True

The Coast Ranges of California are made of debris that was scraped off the Pacific Ocean floor as an accretionary wedge at a time when there was a subduction zone immediately to the west. What is now the Central Valley of California was originally a shallow marginal ocean basin between the trench and accretionary wedge offshore and the continental volcanic arc on land. True False

True

What is the structure below? (lake Michigan ) an anticline a dome a syncline a basin

a basin

At Siccar Point on the coast of Scotland we find a famous feature known as an unconformity, similar to unconformities that are found elsewhere around the world. What is an unconformity? a boundary between rock layers that marks a gap in the geologic record caused by a period of erosion or a period when no deposition occurred before new sediments were deposited a fold or a fault an igneous intrusion between two sedimentary rock layers all of the above

a boundary between rock layers that marks a gap in the geologic record caused by a period of erosion or a period when no deposition occurred before new sediments were deposited

Shale is a coarse-grained clastic sedimentary rock formed from deposits in a high-energy environment such as a river or beach a chemical sedimentary rock made of shell fragments a chemical sedimentary rock made of evaporite deposits precipitating out of solution in a saline lake in an arid environment a fine-grained clastic sedimentary rock made of silt and clay deposited in a low-energy environment such as a swamp or the deep ocean floor a fine-grained chemical sedimentary rock formed by water that drips and evaporates to leave behind calcium carbonate deposits in caves

a fine-grained clastic sedimentary rock made of silt and clay deposited in a low-energy environment such as a swamp or the deep ocean floor

Which of the following describes the major change in the fossil record that appears at the beginning of the Cambrian Era? a global extinction event that killed off the great majority of all species in existence at that time a rapid increase in the diversity of fossil life forms preserved in the geologic record, including the development of inorganic skeletal parts a sudden episode of global cooling leading to a long period of alternating ice ages and interglacial periods the development of the very first single-celled organisms

a rapid increase in the diversity of fossil life forms preserved in the geologic record, including the development of inorganic skeletal parts

The mid-ocean ridge is a region where oceanic crust sinks into the mantle and is consumed a region where plates move past each other laterally a region where two oceanic plates have collided, creating a chain of mountains on the sea floor a region where the ocean floor spreads apart, magma rises from the mantle and new oceanic crust is created none of the above

a region where the ocean floor spreads apart, magma rises from the mantle and new oceanic crust is created

Chemical sediments form from fossilized shells of living organisms by evaporation of a solution and precipitation of solids from that solution through preservation, heating, and compression of hydrocarbon compounds in solid form by precipitation of carbonates and other minerals from solution in caves and in hot springs all of the above

all of the above

Limestone, made of calcium carbonate, can be made in which of the following ways? preservation of shells from invertebrate animals cave deposits in regions with carbonate bedrock cementation of microfossils from floating marine organisms to create chalk deposits preservation of remnants of a coral reef all of the above

all of the above

The pathways illustrated in the rock cycle indicate that metamorphic rocks may be melted to form magma igneous rocks may be weathered, eroded, transported and deposited to form sediments and sedimentary rocks igneous rocks can be subjected to high temperature and pressure to form metamorphic rocks sedimentary rocks can be subjected to high temperatures and pressures to form metamorphic rocks metamorphic rocks may be weathered, eroded, transported and deposited to form sediments and sedimentary rocks all of the above are true

all of the above are true

Transform faults typically form at a convergent boundary where thrust faulting causes slices of the crust to shear off in a sideways direction in the interior of a lithospheric plate where uplift of a plume of magma from deep in the earth's mantle causes the plate to tear apart at a retrocursive plate boundary where there is a sudden shift from convergent to divergent motion along a section of a divergent plate boundary where the transform faults occur as fracture zones offsetting one part of the spreading ridge from another

along a section of a divergent plate boundary where the transform faults occur as fracture zones offsetting one part of the spreading ridge from another

What is a continental shield? a relatively young mountain belt of high relief and high tectonic activity an area of ancient igneous and metamorphic rocks that have been eroded to levels of low relief a passive continental margin with little or no tectonic activity and active deposition of coastal and marine sediments a plate boundary that separates oceanic plates from continental plates

an area of ancient igneous and metamorphic rocks that have been eroded to levels of low relief

What is an orogeny? a type of fault associated with a major earthquake an episode of mountain building the process that leads to creation of magnetic stripes on the ocean floor the breakup of a supercontinent like Pangaea

an episode of mountain building

What steps are NOT involved in formation of sedimentary rock? 1. transportation and deposition of solid particles in environments at earth's surface 2. cooling and crystallization from molten form 3. precipitation of chemical compounds out of solution when water evaporates or organisms make shells 4. deformation under intense pressure and high temperatures 5. burial and cementation 6. answers 2 and 4 above are not involved in formation of sedimentary rock

answers 2 and 4 above are not involved in formation of sedimentary rock

Which type of structure is illustrated below? (structure like: ^) graben syncline basin anticline

anticline

The impact of a meteorite or asteroid with the earth caused one of the earth's great extinctions. When did this happen? at the boundary between the Precambrian and the Phanerozoic eons, about 540 million years ago at the boundary between the Tertiary and the Pleistocene epochs, about 2.6 million years ago at the boundary between the Permian and the Triassic, about 248 million years ago at the boundary between the Cretaceous and the Tertiary periods, about 65 million years ago

at the boundary between the Cretaceous and the Tertiary periods, about 65 million years ago

Which of the following is a normal fault? (b: diagonal, opposite directions with left side higher) a b c None of the above

b

The dominant rock type of the oceanic crust is _________ . granite sandstone conglomerate basalt phyllite

basalt

A very large body of intrusive (or plutonic) igneous rock of felsic composition, which basically is the remant of an extinct magma chamber and is only exposed at earth's surface after a long period of uplift and erosion, is a batholith sill dike volcanic pipe

batholith

How is an overthrust similar to or different from a reverse fault? an overthrust is caused by compression whereas a reverse fault is caused by tension an overthrust is caused by tension whereas a reverse fault is caused by shear stress both are caused by tension but an overthrust is steeper and involves mostly vertical displacement, whereas a reverse fault is a low-angle fault involving mostly horizontal movement both are caused by compressive stress but an overthrust is a low-angle fault involving mostly horizontal movement, whereas a reverse fault is inclined at a steeper angle and involves mostly vertical displacement

both are caused by compressive stress but an overthrust is a low-angle fault involving mostly horizontal movement, whereas a reverse fault is inclined at a steeper angle and involves mostly vertical displacement

What happens along a convergent plate boundary when two continental plates meet? the older continent will be subducted beneath the younger continent they bounce off each other and begin moving apart, leading to upwelling of magma from the mantle and formation of a new ocean they will slide laterally past each other, forming a transform fault boundary both are too buoyant to be subducted and instead a suture zone will form where they collide, with intense compression, deformation, and formation of thrust sheets

both are too buoyant to be subducted and instead a suture zone will form where they collide, with intense compression, deformation, and formation of thrust sheets

How was Iceland created? eruptions along the mid-Atlantic ridge outpouring of flood basalts from a hot spot both of the above subduction of oceanic lithosphere at a site along the mid-Atlantic ridge none of the above

both of the above

Which of the following is not one of the 8 most common elements in the rocks of the earth's crust? oxygen carbon magnesium sodium calcium potassium

carbon

Folds are associated with tensional stress compressive stres shear stress both the first and the second choice above

compressive stres

What do we call a clastic sedimentary rock with a large percentage of particles coarser than 2 mm? conglomerate sandstone shale gypsum either limestone or dolomite

conglomerate

What type of plate boundary is associated with deep trenches on the ocean floor? transform fault boundary convergent boundary divergent boundary retrocursive boundary

convergent boundary

The compositional spectrum within the group of rock-forming minerals described above extends between what end members? felsic (light-colored, less dense) to ultramafic (dark-colored, higher density) clastic (rich in Ca and C) to chemical (rich in Al and K) end members from the oldest (> 2 billion years old) to the youngest (< 10,000 years old) foliated (darker, heavier) to nonfoliated (lighter, less dense) fine-grained (plutonic) to coarse-grained (volcanic)

felsic (light-colored, less dense) to ultramafic (dark-colored, higher density)

How did the structure in the previous question form? compression and folding uplift and stretching gentle downwarping and subsidence rotational motion and twisting of the underlying rocks

gentle downwarping and subsidence

Mafic rocks have more silicon and aluminum than more felsic rocks are found only in the earth's mantle and not i the crust form only as a result of volcanic eruptions that reach the surface have more iron and magnesium than felsic rocks

have more iron and magnesium than felsic rocks

Contact metamorphism is the process of crystallization of igneous rocks that are cooling in a subsurface environment heating and recrystallization of existing rocks that are "baked" when a magma intrudes in close proximity to them intense deformation of existing rocks in a continental collision all of the above

heating and recrystallization of existing rocks that are "baked" when a magma intrudes in close proximity to them

In which of the following environments would you expect to find a metamorphic rock like gneiss? in the Piedmont of Maryland, including multiple locations in Baltimore County along the Atlantic coast of our area at shallow depth beneath beach sands forming on the mid-ocean ridge from cooling and crystallization of magma derived from the mantle forming in shallow lakes in arid desert basins in Utah

in the Piedmont of Maryland, including multiple locations in Baltimore County

Which of the following best describes the textural characteristics of plutonic (i.e. intrusive) igneous rocks? large, interlocking mineral crystals fine, interlocking mineral crystals welded grains of glass lacking defined crystal structure, mixed with inclusions of chemical sediment plutonic rocks may include any or all of the above

large, interlocking mineral crystals

What kind of plate motion occurs at transform faults? divergent convergent lateral offset all of the above can be associated with transform faults

lateral offset

Foliation is layering produced as a result of the deposition of successive layers of sediment over time that are eventually buried, compressed, and cemented together to make a sedimentary rock one end of the compositional spectrum of the mineral group that makes up igneous rocks layering produced in volcanic igneous rocks by successive lava flows and ash deposits as they are deposited over time layering characteristic of many metamorphic rocks that is produced by differential stresses and compression that reorients and recrystallizes mineral grains

layering characteristic of many metamorphic rocks that is produced by differential stresses and compression that reorients and recrystallizes mineral grains

Which of the following is a chemical sedimentary rock? sandstone limestone shale conglomerate

limestone

What is the difference between mafic and felsic minerals? felsic are richer in iron and magnesium mafic are lighter in color and lower in density mafic are found in continental crust and felsic are found in the mantle mafic minerals are darker and denser

mafic minerals are darker and denser

Which of the following is a metamorphic form of limestone? marble quartzite schist slate gneiss limestone is a metamorphic rock to begin with, therefore no other rock can be a metamorphic form of limestone

marble

Rocks of the ocean floors are about the same age as continental rocks much older than continental rocks no more than about 200 million years old, whereas some continental rocks are as old as several billion years oldest in the vicinity of the mid-ocean ridge and progressively younger in either direction away from a ridge

no more than about 200 million years old, whereas some continental rocks are as old as several billion years

Fault-block mountains in the Basin and Range province of the western U.S. are associated with what type of fault? reverse normal transcurrent or strike slip overthrust none of the above

normal

How does oceanic crust compare with continental crust? oceanic crust is thinner (up to ~5 km) and denser (3.0 g/cm3) than continental crust (~25-40 km, 2.7 g/cm3) oceanic crust is thinner (up to ~5 km) and less dense (2.7 g/cm3) than continental crust (25-40 km, 3.0 g/cm3) they have the same composition and density oceanic crust is more brittle and has a greater tendency to fault and fracture compared with continental crust, which is more likely to bend and stretch under stress

oceanic crust is thinner (up to ~5 km) and denser (3.0 g/cm3) than continental crust (~25-40 km, 2.7 g/cm3)

Which of the earth's interior layers is composed mostly of molten iron? outer core inner core lower mantle asthenosphere megasphere

outer core

The creation of these magnetic stripes is a result of periodic reversal of the polarity of the earth's magnetic field, which has occurred many times in earth history but without predictable timing reversals of polarity of the earth's magnetic field that occur at regular intervals and are accompanied by episodes of intense bombardment by cosmic rays and massive extinction events bombardment of the earth by swarms of meteorites that contain large concentrations of magnetic minerals which settle out on the ocean floor and are incorporated into its rocks none of the above are true

periodic reversal of the polarity of the earth's magnetic field, which has occurred many times in earth history but without predictable timing

What range of particle sizes falls between 0.062 mm and 2 mm in diameter? gravel sand silt clay

sand

Magnetic stripes on the ocean floor provide strong supporting evidence for the existence of what process? subduction sea-floor spreading transform faulting shifting of the poles is association with major earthquakes

sea-floor spreading

What type of stress is associated with the faults mentioned in the previous question? compressional stress shear stress tensional stress none of the above

shear stress

The micas belong to the major mineral group we have been discussing, which has several different structural types. Which of these best describes the micas? 3-d framework structure single chain double chain sheet structure

sheet structure

The dominant group of rock-forming minerals in the earth's crust all have structures with a basic building block made of which two elements? carbon and oxygen iron and magnesium nitrogen and calcium potassium and sodium silicon and oxygen

silicon and oxygen

The San Andreas and North Anatolian faults are both normal faults strike-slip faults reverse faults overthrusts

strike-slip faults

What type of stress is associated with the faults in the previous question? compressional stress shear stress tensional stress none of the above

tensional stress

Where in the world today can you see a young divergent plate boundary in the early stages of formation? the Red Sea and the East African rift valley the San Andreas fault along the coast of California the Himalayas at the boundary between Asia and the Indian subcontinent Japan, the Philippines, and the Aleutian Islands off the coast of Alaska

the Red Sea and the East African rift valley

How does the lithosphere compare with or relate to the asthenosphere? the lithosphere is made up dominantly of oceanic crust and the asthenosphere is made up dominantly of continental crust the lithosphere is found underneath the asthenosphere and is hotter, denser and older the lithosphere is composed of the crust and uppermost mantle and is more rigid and brittle than the underlying asthenosphere, which is closer to the melting point and is more plastic and deformable the lithosphere is found at the earth's surface whereas the asthenosphere is a layer within the earth's outer core

the lithosphere is composed of the crust and uppermost mantle and is more rigid and brittle than the underlying asthenosphere, which is closer to the melting point and is more plastic and deformable

What is isostasy? the change in chemical composition that occurs as a magma cools and crystallizes the change in density that occurs as a result of metamorphism the principle that lithospheric rocks of lower density "float" on the more plastic asthenosphere and may subside when a load is added or rebound when a load is removed the concept that the mantle cools through time as it ages, which will eventually lead to the cessation of convection in the earth's interior

the principle that lithospheric rocks of lower density "float" on the more plastic asthenosphere and may subside when a load is added or rebound when a load is removed

When we interpret the geologic record preserved in the earth's rocks, rules like Steno's law of superposition and the principle of faunal sucession are useful because they allow us to figure out the relative sequence of formation of different rock layers even if we don't know their age in years they provide direct quantitative information about the age of the rocks they provide information about how a continent like North America was assembled by successive episodes of collision with terranes accreting onto the edge of the continent all of the above

they allow us to figure out the relative sequence of formation of different rock layers even if we don't know their age in years

Which of the following does NOT provide diagnostic information about the environment in which sediments were deposited before being turned into sedimentary rock? particle size mineral composition stratification and geometric organization of layers to form structures like cross-bedding fossils unconformities between different rock layers

unconformities between different rock layers

Which of the following describes the differences you see in rocks as you progress from low-grade to high-grade metamorphism? high-grade metamorphic rocks are darker in color and higher in density than low-grade metamorphic rocks high-grade metamorphic rocks are crushed and ground down so that they have much finer particle sizes than low-grade metamorphic rocks with increasing temperature and pressure, metamorphic rocks show signs of more intense deformation and segregation of mineral into discrete bands that become thicker and more contorted and irregular in shape all of the above are true

with increasing temperature and pressure, metamorphic rocks show signs of more intense deformation and segregation of mineral into discrete bands that become thicker and more contorted and irregular in shape