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Chapters 6, 7, 9 & 10

quartz

is the most common mineral in sandstones.

Compaction of sediment tends to

reduce the volume of pore space.

A cherty limestone contains which major constituents?

clay minerals

Which of the following best describes bedded gypsum and halite

evaporites (one type of chemical sedimentary rock).

Arkose

is a sandstone contains abundant feldspar, suggesting that the sand was derived by weathering and erosion of granitic bedrock.

Iron oxide

is a sandstone contains abundant feldspar, suggesting that the sand was derived by weathering and erosion of granitic bedrock.

What is the main difference between a conglomerate and a sedimentary breccia?

Breccia clasts are angular; conglomerate clasts are rounded.

Which type of limestone consists mainly of tiny, marine fossils composed of calcite

chalk

Fluorite

is not a common cement mineral for sandstones.

Chert is a microcrystalline form of the mineral

quartz

Which of the following sedimentary rocks would you expect to have originally been deposited by fast-moving streams

conglomerate

Which of the following sedimentary features would typically be found in shales but not in sandstones?

mud cracks

Which one of the following is not a chemical sedimentary rock?

shale

Which of the following is not a type of limestone?

arkose

Which of the following sedimentary features can each be used to determine paleocurrent directions?

current ripple marks

Coal beds are derived from plants that lived in

freshwater coastal swamps and bogs.

Clay and muddy sediments lithify to form shales and mudstones

true

Most marine limestones are of biochemical origin.

true

Mud cracks in a shale or mudstone indicate that the mud or clay was deposited in deep waters of an offshore marine environment.

true

Detrital sedimentary rocks are classified according to clastic particle size; chemical sedimentary rocks are named according to the most abundant minerals.

true

Of the following four rocks, which forms at the highest grade during regional metamorphism?

gneiss

Which low-grade metamorphic rock, composed of extremely fine-sized mica and other mineral grains, typically exhibits well-developed rock cleavage?

slate

Which of the following statements concerning slate is not true

has abundant, coarse-grained mica

Foliation

is a planar fabric in a metamorphic rock due to a preferred alignment of platy or elongate mineral grains.

Quartzite

is a nonfoliated rock formed by contact metamorphism of a sandstone.

Which of the following best describes the conditions of contact metamorphism?

pressures are fairly low, the rock is in the upper part of the crust, and heat is supplied from a nearby magma body

Marble

forms from the metamorphism of limestone or dolostone.

What foliated, metamorphic rock is texturally intermediate between slate and schist?

fault breccia

Granitic gneiss

is characterized by the segregation of light- and dark-colored minerals into thin layers or bands.

Which metamorphic rock consists mostly parallel aligned coarse-grained, mica flakes?

schist

Which of the following lists the rocks in the order of increasing grain size and increasing grade of metamorphism?

slate, phyllite, schist

Which of the following rocks is foliated?

slate

What is the major source of heat for contact metamorphism

heat from a nearby magma body

A migmatite

forms at very high temperature and involves partial melting of rock as well as metamorphism.

Calcite is the main mineral constituent of the sedimentary rock limestone and of the metamorphic rock marble.

true

Metamorphic rocks formed during episodes of mountain building typically show textural characteristics indicative of shearing stress and deformation

true

Foliated metamorphic rocks are composed largely of equidimensional grains of minerals such as quartz and calcite.

false

Rock cleavage in slates (slaty cleavage) is largely a consequence of abundant, parallel-aligned, very fine-grained mica flakes in the rock.

true

The distinctive layers or bands of different minerals in gneisses may be complexly folded

true

High-grade, regional metamorphism produces significant and recognizable changes in the textures and mineral compositions of rocks.

true

How does urbanization (paving, etc.) affect runoff and infiltration in a small, previously forested, drainage basin?

infiltration decreases; runoff increases

Silt and clay-sized, detrital grains

make up the suspended loads of most rivers and streams.

At the head of a delta, the major channel splits into smaller channels that follow different paths to the sea. These smaller channels are known as

distributaries

A radial

stream pattern is developed only on growing mountains like volcanoes or where the land surface is tectonically doming upward.

A trellis

stream pattern develops on lands underlain by tilted or folded, alternating hard and soft, sedimentary strata.

An oxbow

is an abandoned, cutoff, meander loop that is now a lake.

Rapids and lots of whitewater

are characteristics of downcutting streams and a youthful stage of valley evolution.

Many larger rivers in the Colorado Plateau region meander in deep, narrow canyons and have no floodplains. How could this happen?

meandering streams became rejuvenated, starting to downcut as the land gradually rose

The Amazon

has the largest discharge of any in the world.

Where is erosion concentrated along a meandering stream

on the outer parts of the meander loops or bends

Which one of the following would cause stream rejuvenation?

the land is uplifted

A stream begins at an elevation of 200 meters and flows a distance of 400 kilometers to the ocean? What is the average gradient?

0.5m/km

Gradients usually decrease downstream in a major river system

true

Point bars are depositional features located along the outer portions of meander bends

false

Rapids and waterfalls are characteristic of laterally cutting (meandering) streams.

false

After a meander is cut off, the gradient through the newly formed cutoff is steeper than the gradient along the abandoned meander loop

true

Stream discharge is defined as the quantity of water flowing past a specific channel location per unit time

true

A V-shaped valley and no floodplain indicate a youthful, downcutting stream

true

Lateral cutting and deposition are important factors in floodplain development.

true

All else being equal, a stream with a boulder-strewn bed would be more turbulent than one with a sandy bed.

true

Permeability

describes the ease of fluid transmission through rock.

The most useful aquifers for obtaining abundant groundwater possesses

high potability and high portability

A perched water table develops when

a horizontal aquitard above the regional water table lies below an aquifer.

An artesian well is one in

water rises above the top of the aquifer without any pumping.

Excessive groundwater withdrawals can cause

the water table to fall.

Which of the following geologic materials would have the highest groundwater velocities and be least effective in removing unwanted pollutants from the water?

limestone; numerous solution channels and fractures widened by dissolution

A stalactite

is the icicle-like speleothem that grows down from the roof of a cavern.

Which of the following can possibly contaminate an aquifer?

pesticides, industrial chemicals, sewage (all of the above)

The unsaturated zone of an aquifer

lies above the water table.

An aquifer is

a permeable rock unit that possesses a saturated zone.

Which of the following describes the configuration of an unconfined water table around a pumping well?

cone of depression

Porosity

is the percentage of a rock or unconsolidated sediment that consists of empty space.

An unconfined water table is

the boundary between the unsaturated zone above and saturated zone below.

Which of the following best describes how geysers erupt?

with a slight reduction in pressure, water in a saturated, natural conduit suddenly boils, sending a plume of steam and hot water into the air above the vent

he water table is a surface separating the saturated and unsaturated zones.

true

In areas with humid climate, the water table of an unconfined aquifer generally slopes downward towards stream valleys.

true

Most caves and caverns originate by dissolution of limestone.

true

Water-saturated muds have low permeabilities but can have greater porosities than well-cemented sandstone

true

In areas underlain by unconsolidated or weakly consolidated strata, lowering of the water table can cause the land to subside

true

In general, contaminated groundwater will be naturally cleaned faster by circulation through porous and permeable sands than by circulation through fractured, crystalline igneous and metamorphic rocks

true

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