Geo Midterm #2

An unknown mineral scratches glass, has only average specific gravity, and shows no cleavage but does show conchoidal fracture. Which of the following could it be?
Select one:
a. quartz
b. talc
c. halite
d. mica

a. quartz

Calcite and aragonite minerals that constitute clam shells are examples of which method of mineral formation?
Select one:
a. solidification of a melt
b. precipitation from a solution
c. solid-state diffusion
d. biomineralization

d. biomineralization

Graphite is:
Select one:
a. the polymorph of galena.
b. harder than glass.
c. pure silicon.
d. the "lead" in the pencil you write with.

d. the "lead" in the pencil you write with.

Identify the FALSE statement. Silicates:
Select one:
a. have the silicon-oxygen tetrahedron as their structural unit.
b. are a major component of continental crust.
c. are classified on the basis of how the tetrahedrons join and share oxygen atoms.
d. are

d. are a large category of minerals and include the common minerals calcite and dolomite.

Identify the FALSE statement:
Select one:
a. Crystals can be a variety of geometric shapes, including cubes, trapezoids, pyramids, octahedrons, hexagons, columns, blades, and needles.
b. Negative ions are called cations and have more protons than electron

b. Negative ions are called cations and have more protons than electrons; positive ions are anions and have more electrons than protons.

The tendency of a mineral to break and produce smooth, curving shell-shaped surfaces is termed:
Select one:
a. luster.
b. perfect cleavage.
c. conchoidal fracture.
d. streak.

c. conchoidal fracture.

There are two physical properties of minerals that both result in smooth, flat surfaces with specific angles between them. The first property is externally visible and is the result of how the mineral forms; the second is inherently internal and is the re

c. crystal habit and cleavage.

When you scrape a mineral along a ceramic plate to observe the color of its powder, you are checking the physical property known as:
Select one:
a. streak.
b. luster.
c. cleavage.
d. specific gravity.

a. streak.

Which is NOT a physical property commonly used in the lab or field to identify minerals?
Select one:
a. color
b. specific gravity
c. luster
d. X-ray diffraction

d. X-ray diffraction

Which of the following groups of silicate minerals exhibits a single strong cleavage in one direction?
Select one:
a. framework silicates
b. sheet silicates
c. independent tetrahedra silicates
d. single-chain silicates

b. sheet silicates

Which of the following is a mineral?
Select one:
a. amber (tree sap)
b. oyster shell (CaCO3)
c. sugar (formula C6H12O6)
d. glass

b. oyster shell (CaCO3)

Which of the following is NOT a mineral?
Select one:
a. oil, because it's a liquid, not a solid
b. salt, because it's not crystalline
c. a gold nugget, because it's a native metal
d. pyrite, because it's a chemical compound

a. oil, because it's a liquid, not a solid

Which of the following statements accurately describes a property that is NOT useful in identifying quartz?
Select one:
a. Color, because quartz can be many different colors.
b. Fracture, because quartz does not have fracture.
c. Hardness, because quartz

a. Color, because quartz can be many different colors.

Which of the following statements is FALSE? Crystals:
Select one:
a. have an orderly internal arrangement of atoms arranged in a lattice pattern.
b. grow outward from a seed.
c. are formed by the high-temperature, extremely rapid process known as solid-st

c. are formed by the high-temperature, extremely rapid process known as solid-state diffusion.

Which of the following statements is FALSE? Formation of table salt:
Select one:
a. is, in mineralogic terms, formation of the halide mineral halite.
b. takes place when a solution has become saturated.
c. is an example of solidification of a melt.
d. res

c. is an example of solidification of a melt.

Which of the following statements is TRUE?
Select one:
a. Hydrogen has an atomic mass of 1.
b. An isotope of an element has the same atomic mass, but different atomic number.
c. Helium has an atomic number of 2.
d. The atomic mass of an element is approxi

c. Helium has an atomic number of 2.

Wet" igneous rock melts at a lower temperature than the "dry" version of that same rock because
Select one:
a. the addition of volatiles in "wet" rocks lowers their melting temperature.
b. they occur on the sea floor, where temperatures are already cold.

a. the addition of volatiles in "wet" rocks lowers their melting temperature.

A black, fine-grained tabular intrusion between two layers of horizontal sedimentary rock must logically be a
Select one:
a. basaltic sill.
b. granitic sill.
c. basaltic dike.
d. granitic dike.

a. basaltic sill.

After an explosive volcanic eruption on an island, the surrounding sea is full of light-gray floating rock. What must it be?
Select one:
a. rhyolite
b. pumice
c. obsidian
d. basalt

b. pumice

An igneous rock has a medium-gray, fine-grained groundmass with large crystals of plagioclase. Which of the following statements about it is false?
Select one:
a. It could logically be porphyritic andesite.
b. The lava flow that produced it got quenched i

b. The lava flow that produced it got quenched in ocean water.

Bowen's Reaction Series
Select one:
a. shows that minerals crystallize in a random order, with no particular pattern involved.
b. allows a geologist to predict what minerals will be found in a given igneous rock.
c. is an attempt to explain the logic of f

b. allows a geologist to predict what minerals will be found in a given igneous rock.

Bowen's Reaction Series
Select one:
a. shows the sequence in which different sulfate minerals form during the progressive cooling of a melt.
b. creates a progressively more mafic melt.
c. has a continuous track in which there is observed a progressive cha

c. has a continuous track in which there is observed a progressive change from calcium-rich to sodium-rich plagioclase.

Granite
Select one:
a. is an extrusive igneous rock.
b. is felsic in composition.
c. logically could be found in a lava flow.
d. is the coarse-grained equivalent of andesite.

b. is felsic in composition.

How does subduction trigger melting?
Select one:
a. Flux melting of the asthenosphere above the subducting slab creates a rising melt.
b. The downgoing slab melts as it reaches hotter temperatures deep in the Earth.
c. The overriding slab insulates the su

a. Flux melting of the asthenosphere above the subducting slab creates a rising melt.

Identify the FALSE statement. Magma moves upward toward the Earth's surface
Select one:
a. because it's less dense than the surrounding rock.
b. slowly, working its way up through cracks and narrow conduits.
c. more quickly as it cools and therefore becom

a. because it's less dense than the surrounding rock.

Identify the false statement. Early Earth had numerous heat sources for igneous activity, including
Select one:
a. conversion of the kinetic energy of meteorite impact to heat energy.
b. conversion of the kinetic energy of iron alloy sinking toward Earth'

c. decay of all of its radioactive elements; almost none remain today.

Identify the false statement. Hot solid rock in the Earth
Select one:
a. may be even hotter than surface lava because of the pressure of overlying rock.
b. may melt if volatiles such as water and carbon dioxide are added.
c. may melt if heat is transferre

d. maintains uniform composition as it melts and becomes magma.

Identify the false statement. Large igneous provinces (LIPs)
Select one:
a. are places where huge amounts of mafic magma have been erupted or intruded.
b. represent special events in Earth's history that may have been caused by superplume activity.
c. occ

c. occur only along continental margins.

Identify the false statement. Pegmatites
Select one:
a. have intruded at great depth and cooled very slowly.
b. can contain crystals up to tens of centimeters across.
c. occur in tabular intrusions called pegmatite dikes.
d. are an igneous rock type, dist

a. have intruded at great depth and cooled very slowly.

Intrusive igneous rocks
Select one:
a. cool slowly and are coarse-grained.
b. are fine-grained because they cooled slowly.
c. are never seen by humans because they form deep in the Earth and are never exposed at the surface.
d. are rocks like basalt, ande

a. cool slowly and are coarse-grained.

Magma may cool and crystallize to become solid igneous rock
Select one:
a. when its volatile content increases.
b. more slowly in the presence of circulating groundwater.
c. faster if the surface area of the intrusion is low.
d. very slowly (centuries to

d. very slowly (centuries to a million years) when it forms a deep pluton.

Magmas have a variety of chemical compositions because of all of the following except
Select one:
a. they come from a variety of source rocks.
b. the rocks that melt to make magma are composed of many minerals, not all of which melt under the same conditi

d. different magmas formed in different locations are isolated and don't mix.

Pillow basalts
Select one:
a. occur in tabular intrusions called dikes.
b. are composed of felsic lava.
c. are formed in a submarine environment.
d. contain large bulbous crystals that cool slowly.

c. are formed in a submarine environment.

What are vesicles?
Select one:
a. pieces of wall rock broken off by intruding magma
b. large crystals floating in a fine-grained groundmass
c. air pockets or bubbles frozen in igneous rocks as gas escaped during cooling
d. horizontal igneous intrusions

c. air pockets or bubbles frozen in igneous rocks as gas escaped during cooling

Which is not a tectonic setting for igneous activity?
Select one:
a. hot spots
b. continental rifts
c. continental transform fault zones
d. volcanic arcs bordering ocean trenches

c. continental transform fault zones

Which of the following is not an intrusive igneous structure?
Select one:
a. batholiths
b. laccolith
c. pillow lava
d. sill

c. pillow lava

Which of the following statements is false? Felsic (or silicic) magma
Select one:
a. crystallizes at the lowest temperatures.
b. has about 70% silica and little magnesium and iron.
c. is likely to form light tan, pink, or maroon rocks.
d. is less viscous

d. is less viscous than mafic magma.

Which of the following statements is false? Igneous rocks
Select one:
a. form from the cooling and crystallization of either lava or magma.
b. form in great quantity along the mid-ocean ridge.
c. were the first rocks to exist on Earth.
d. are coarse-grain

d. are coarse-grained if they cool extrusively.

Which of the following statements is false? Mafic minerals
Select one:
a. crystallize at a higher temperature than do silicic minerals.
b. are rich in iron and magnesium.
c. typically crystallize first out of a melt.
d. form rhyolite and granite.

d. form rhyolite and granite.

Which of the following statements is false? Volatiles that come out of the Earth as volcanic products
Select one:
a. were dissolved in the molten rock and released as the surrounding pressure lessened.
b. usually consist of 50% sulfur dioxide.
c. include

b. usually consist of 50% sulfur dioxide.

Which of the following statements is false? Volcanic arcs
Select one:
a. form where subduction takes place.
b. are long, curving mountain chains adjacent to deep-ocean trenches.
c. can be continental or island-related.
d. occur at divergent-plate boundari

d. occur at divergent-plate boundaries.

Which of the following terms has nothing to do with intrusive igneous activity?
Select one:
a. pluton
b. batholith
c. diapir
d. hyaloclastite

d. hyaloclastite

Which of the following words could not be used to describe portions of a rock with a porphyritic texture?
Select one:
a. groundmass
b. phenocryst
c. plagioclase
d. pyroclastic

d. pyroclastic

A clastic sedimentary rock with clay and silt-sized grains that breaks in thin sheets is called:
Select one:
a. mudstone.
b. shale.
c. siltstone.
d. graywacke.

b. shale.

A nonmarine clastic sedimentary rock composed of angular pebble-sized fragments surrounded by matrix is:
Select one:
a. breccia.
b. conglomerate.
c. turbidite.
d. arkose.

a. breccia.

As sediment is transported downstream, away from its point of origin, the particles become:
Select one:
a. smaller.
b. more angular.
c. poorly sorted.
d. dominantly feldspar.

a. smaller.

Flint was prized in early human cultures because:
Select one:
a. large outcrops of them often contained caves to live in.
b. they are translucent minerals and were useful for windows.
c. they broke with conchoidal fracture and thus made good cutting tools

c. they broke with conchoidal fracture and thus made good cutting tools.

Formation of a clastic sedimentary rock involves five stages. Which of the following describes erosion?
Select one:
a. disintegration of bedrock into separate particles
b. compaction and cementation of loose particles to form solid rock
c. separation of r

c. separation of rock or regolith from its substrate

Geologists find evidence of bioturbation in an area of sedimentary rock. This means they must be looking at:
Select one:
a. deep-marine deposits rich in broken-shell material.
b. the forest beds at the mouth of a major river.
c. a submarine fan with deep

d. bedding layers that have been churned by burrowing creatures like worms and clams.

If you find graywacke in the place where it formed, you know you are looking at an ancient:
Select one:
a. avalanche on a submarine slope.
b. sand dune.
c. swamp.
d. alluvial fan.

a. avalanche on a submarine slope.

Rocks formed dominantly from the calcium carbonate shells of marine organisms are classified as _____ and called _____.
Select one:
a. clastic; arkose
b. organic; coal
c. biochemical; limestone
d. chemical; travertine

c. biochemical; limestone

Sedimentary rocks can form by each of the following processes EXCEPT:
Select one:
a. by the precipitation of minerals from water solution.
b. by the cementing together of loose grains of preexisting rock.
c. from shell fragments or carbon-rich relicts of

d. solidification from a melt.

Symmetrical ripple marks:
Select one:
a. suggest you're looking at an old lake bottom.
b. are parallel to the current direction that created them.
c. could suggest an ancient coastline.
d. are a sure sign the area had periodic drought.

c. could suggest an ancient coastline.

The organic sedimentary rock that is composed of mud-sized particles and partially decayed organic matter derived from plankton and algae remains is:
Select one:
a. coal.
b. fossiliferous limestone.
c. chert.
d. oil shale.

d. oil shale.

Which of the following features is a bed-surface marker, meaning it appears on the surface of a bed due to events during or soon after sediment deposition?
Select one:
a. laminations
b. cross beds
c. graded bedding
d. mudcracks

d. mudcracks

Which of the following is NOT one of the major classes of sedimentary rocks?
Select one:
a. clastic
b. biochemical
c. chemical
d. intrusive

d. intrusive

Which of the following lists accurately describes grain size increasing from smallest to largest?
Select one:
a. sand, silt, pebbles
b. mud, silt, sand
c. silt, mud, sand
d. sand, cobbles, pebbles

b. mud, silt, sand

Which of the following processes is associated with the formation of travertine?
Select one:
a. deposition
b. lithification
c. compaction
d. precipitation

d. precipitation

Which of the following rock types does not contain the mineral calcite?
Select one:
a. chert
b. fossiliferous limestone
c. chalk
d. micrite

a. chert

Which of the following sedimentary structures indicates that the sediments were deposited in a moving fluid?
Select one:
a. mudcracks
b. fossil footprints
c. ripple marks
d. laminations

c. ripple marks

Which of the following statements is TRUE?
Select one:
a. Conglomerates consist of a single grain size.
b. Pieces of broken rock produced by physical weathering are collectively called clasts or detritus.
c. A well-sorted clastic rock is made up of differ

b. Pieces of broken rock produced by physical weathering are collectively called clasts or detritus.

Which statement is FALSE?
Select one:
a. Both chert and limestone may have either chemical or biochemical origin.
b. Flint, jasper, agate, and petrified wood are all varieties of the siliceous rock travertine.
c. Gypsum and halite are evaporite minerals.

b. Flint, jasper, agate, and petrified wood are all varieties of the siliceous rock travertine.

Choose the listing that shows the rocks in increasing degrees of metamorphism (i.e., from lower to higher grade).
Select one:
a. migmatite, flattened-clast conglomerate, gneiss with mica, gneiss without mica
b. flattened-clast conglomerate, gneiss with mi

b. flattened-clast conglomerate, gneiss with mica, gneiss without mica, migmatite

Identify the FALSE statement. Hydrothermal fluids:
Select one:
a. may consist of hot water, steam, and supercritical fluid.
b. are chemically active solutions, not pure water.
c. change a rock's chemical composition, a process known as exhumation.
d. can

c. change a rock's chemical composition, a process known as exhumation.

Identify the FALSE statement. Recrystallization:
Select one:
a. occurs because thermal energy causes atoms to vibrate rapidly, breaking existing chemical bonds.
b. changes the mineralogical composition of the protolith.
c. changes the texture (shape and s

b. changes the mineralogical composition of the protolith

Identify the FALSE statement. The sediments in a subsiding sedimentary basin:
Select one:
a. experience increased pressure and temperature due to the weight of the overburden and the geothermal gradient.
b. undergo diagenetic changes when they're at shall

d. become high-grade foliated metamorphic rocks at depth.

Metamorphic aureoles typically contain nonfoliated rock like hornfels because:
Select one:
a. they form adjacent to an intruding pluton, which provides heat for metamorphism.
b. they form as a consequence of shearing without a subsequent change in tempera

a. they form adjacent to an intruding pluton, which provides heat for metamorphism.

Normal stress:
Select one:
a. is a push (compression) or pull (tension) perpendicular to a surface.
b. is the reason a balloon collapses when you take it to the bottom of a pool.
c. occurs when rocks move sideways relative to each other.
d. is a compressi

a. is a push (compression) or pull (tension) perpendicular to a surface.

Quartzite:
Select one:
a. is basically a solid mass of interlocking quartz grains.
b. breaks around the separate grains of quartz that make it up.
c. is always either white or gray.
d. always shows strong compositional banding.

a. is basically a solid mass of interlocking quartz grains.

What is the protolith of marble?
Select one:
a. quartz sandstone
b. limestone
c. phyllite
d. gypsum

b. limestone

What type of foliation does slate, a common material used for roof shingles, exhibit?
Select one:
a. banding
b. cleavage
c. schistosity
d. metamorphic differentiation

b. cleavage

Which is NOT a common process by which metamorphic rocks are formed?
Select one:
a. pressure solution
b. plastic deformation
c. schistosity
d. recrystallization

c. schistosity

Which of the following does NOT describe a change induced on protolith rocks due to mountain building as a result of convergent-margin tectonics and continental collision?
Select one:
a. Surface rock is sent to great depths beneath the new mountain belt.

c. Hot magma rising beneath the converging continents heats seawater, which then rises through the crust to react with the surface rocks.

Which of the following is NOT one of the classification terms used to sort metamorphic rocks based on their chemical composition?
Select one:
a. quartzo-feldspathic (rich in quartz and feldspar)
b. glaucophanitic (rich in glaucophane)
c. calcareous (rich

b. glaucophanitic (rich in glaucophane)

Which of the following locations could not possibly be part of a shield?
Select one:
a. Hawaii
b. Canada
c. Northern Europe
d. Siberia

a. Hawaii

Which of the following rocks is classified as nonfoliated?
Select one:
a. hornfels
b. phyllite
c. slate
d. schist

a. hornfels

Which of the following statements about metamorphic rocks and their characteristic environments is TRUE?
Select one:
a. Gneiss is found in metamorphic aureoles surrounding plutons.
b. Mylonites are found along convergent-plate boundaries where magma is ri

c. Slate, phyllite, schist, and gneiss are found in areas of continental collision.

Which of the following statements is FALSE? A metamorphic rock:
Select one:
a. may be composed of different minerals than its protolith.
b. may develop a texture of interlocking grains.
c. cannot be formed below 1200 degrees C.
d. may have preferred miner

c. cannot be formed below 1200 degrees C.

Which of the following statements is FALSE? Extremely high heat of metamorphism:
Select one:
a. causes mica to react and become feldspar or some other water-free mineral.
b. drives off water, causing high-grade metamorphic rocks to be drier than low grade

d. is necessary to elongate the large clasts in conglomerate to make flattened-clast conglomerate (metaconglomerate).

Which of the following statements is FALSE? Retrograde metamorphism:
Select one:
a. may happen as uplift and erosion bring rock closer to Earth's surface.
b. requires the addition of hot water to replace water driven off during prograde metamorphism.
c. r

c. requires very high pressures but needs only low temperatures to occur.

Which of the following statements is FALSE? Shields:
Select one:
a. are composed of the oldest rock on Earth.
b. are composed of extensive areas of sedimentary layers laid down on lava flows.
c. are composed of rocks that were metamorphosed during Precamb

b. are composed of extensive areas of sedimentary layers laid down on lava flows.

Which of the following statements is FALSE? Shock metamorphism:
Select one:
a. involves high temperatures and compressional stress.
b. can be caused by meteorite impact.
c. causes quartz to recrystallize into coesite.
d. probably hasn't happened on the Mo

d. probably hasn't happened on the Moon because no products of shock metamorphism have been found in Moon regolith.

Which of the following statements is FALSE?. Mylonite:
Select one:
a. forms by recrystallization in a fault zone.
b. is produced by shear stress on softened rock.
c. has pronounced foliation parallel to the direction of faulting.
d. is a product of gneiss

d. is a product of gneiss melting to produce felsic magma and solid mafic rock.