Deck 7: Pages of Earths Past: Sedimentary Rocks

Question 1

Grains become rounded primarily during ________.

A)weathering at the outcrop
B)lithification
C)transportation
D)deposition

Answer 1

C

Question 2

Chemical and biochemical rocks are classified primarily on the basis of ________.

A)grain size
B)degree of sorting
C)angularity
D)mineral composition

Answer 2

D

Question 3

Lithified detritus (breakdown products of preexisting rocks)forms which kind of sedimentary rock?

A)biochemical
B)chemical
C)clastic
D)organic

Answer 3

C

Question 4

The removal of detritus from weathered rock at an outcrop is termed ________.

A)deposition
B)erosion
C)weathering
D)lithification

Question 5

Chemically precipitated limestone that forms in caves or around hot springs is termed ________.

A)agate
B)dolostone
C)jasper
D)travertine

Question 6

Two major sources of energy,coal and oil shale,are considered ________ sedimentary rocks.

A)clastic
B)biochemical
C)organic
D)chemical

Question 7

When limestone becomes chemically altered so that half of the calcium atoms are replaced by magnesium,the resultant rock is termed ________.

A)agate
B)dolostone
C)jasper
D)travertine

Question 8

Which of the following is NOT true in regard to biochemical chert?

A)It is bedded (layered).
B)It is made up of the skeletons of radiolaria and foraminifera.
C)It typically exhibits conchoidal fracture.
D)It is composed of the minerals calcite and dolomite.

Question 9

The majority of the rocks that occur at the surface of Earth are ________.

A)intrusive igneous rocks
B)extrusive igneous rocks
C)sedimentary rocks
D)metamorphic rocks

Question 10

Clastic sedimentary rocks are primarily classified on the basis of ________.

A)grain size
B)degree of sorting
C)angularity
D)mineral composition

Question 11

A fine-grained clastic sedimentary rock that splits into thin sheets is ________.

A)mudstone
B)shale
C)sandstone
D)arkose

Question 12

A clastic rock composed of sand-sized grains derived from the physical weathering of granite and containing a sizable proportion of feldspar is termed ________.

A)metasandstone
B)lithosandstone
C)wacke
D)arkose

Question 13

The primary difference between breccia and conglomerate is that conglomerate ________.

A)is finer grained than breccia
B)is coarser grained than breccia
C)possesses more angular grains than breccia
D)possesses more rounded grains than breccia

Question 14

Cemented shells of marine organisms form which kind of sedimentary rock?

A)biochemical
B)chemical
C)clastic
D)organic

Question 15

Biochemical limestones are dominated by carbonate mud and fragments of ________.

A)siliceous shells of planktonic diatoms and foraminifera
B)skeletons of marine invertebrates made of calcite and aragonite
C)the phosphatic bones of fish
D)the organic breakdown products of wood and leaves from trees

Question 16

The image below shows an outcrop of coarse-grained sedimentary rock.Note the rock hammer for scale.What is the name of this rock type?

A)sandstone
B)shale
C)breccia
D)conglomerate

Question 17

The breakdown of exposed rock into small fragments and dissolved ions is termed ________.

A)deposition
B)erosion
C)weathering
D)lithification

Question 18

Which of the following is NOT true? As compared to arkose,quartz sandstone ________.

A)contains more angular grains
B)does not contain significant amounts of feldspar
C)is likely to be found farther away from weathering granitic source rock
D)is considered to be more compositionally mature

Question 19

Compaction and cementation of grains occurs during ________.

A)erosion
B)lithification
C)transport
D)weathering

Question 20

Precipitation of gypsum due to evaporation of seawater produces which kind of sedimentary rock?

A)biochemical
B)chemical
C)clastic
D)organic

Question 21

Siltstone or mudstone containing marine fossils likely formed in a ________ environment.

A)shallow-marine
B)deep-marine
C)marine-delta
D)coastal-beach

Question 22

Consult the figure below.Here,distinct internal laminations are inclined at an angle to the boundary of the main sedimentary layers.This is termed ________.

A)graded beds
B)cross beds
C)horizontal beds
D)tilted beds

Question 23

What type of sediment is typically found in lake bottoms?

A)gravel
B)sand
C)silt
D)clay/mud

Question 24

Which environment would most likely produce sedimentary deposits characterized by very well-sorted,very well-rounded grains that are nearly pure quartz?

A)river
B)glacier
C)beach
D)alluvial fan

Question 25

Glacial till is composed of ________-sized particles.

A)mud
B)sand
C)boulder
D)a mix of anything from mud to boulder

Question 26

Swamps,channels,floodplains,and submarine slopes all play a role in the development of ________.

A)deltas
B)marine deltas
C)alluvial fans
D)turbidites

Question 27

Topset,foreset,and bottomset beds are indicative of ________ environments.

A)alluvial fan
B)lake bottom
C)delta
D)deep-marine

Question 28

When graded beds are observed in a rock outcrop,this tells geologists that a ________.

A)turbidity current deposited these beds,depositing finer material first
B)turbidity current deposited these beds,depositing coarser material first
C)slurry deposited these beds with little sorting
D)glacier deposited these beds,depositing coarser material first

Question 29

If water is the transport mechanism of sediment,the grain size of sedimentary deposits most closely indicates the ________.

A)geographic extent of the weathering source rock at outcrop
B)average velocity of the water from the time of erosion until deposition
C)velocity of the water at the moment the sediment settled to the bottom
D)climate conditions at the time of deposition

Question 30

Limestone is most likely formed in which of the following environments?

A)shallow-marine clastic
B)shallow-marine carbonate
C)marine delta
D)deep marine

Question 31

The image below shows a series of graded beds.How many graded beds are shown?

A)1
B)3
C)12
D)15

Question 32

If a geologist found preserved mud cracks,he or she could conclude that the environment in which they formed ________.

A)was once covered in wet mud
B)was once covered by a glacier
C)has been subjected to a major climate change event
D)was the site of a mass extinction event

Question 33

Which transport medium carries the largest particles?

A)ice in glaciers
B)water in rivers
C)wind
D)water in lakes

Question 34

It is unusual for ________ to carry grains larger than sand.

A)ice in glaciers
B)water in rivers
C)wind
D)water at a seaside beach

Question 35

Which of the following is NOT true? Sediments deposited in a beach environment are typically ________.

A)well sorted
B)medium grained
C)composed of angular grains
D)composed of mostly quartz

Question 36

The image below shows ancient dunes exposed in Zion National Park in Utah.Using the interpreted portion of the image at the left,what was the dominant wind direction that formed these sedimentary structures?

A)toward the right
B)toward the left
C)toward both the left and right
D)vertically both up and down

Question 37

Geologists call individual layers of sedimentary rocks ________,whereas several of them together are called ________.

A)beds;strata
B)strata;beds
C)laminations;graded beds
D)graded beds;laminations

Question 38

The sedimentary rocks breccia and conglomerate most commonly form in a ________ environment.

A)beach
B)lake
C)mountain stream
D)deep-ocean basin

Question 39

Stratification refers to ________.

A)the development of layering within sedimentary rocks
B)the act of deposition of sediment that will ultimately form sedimentary rock
C)physical and chemical alterations,including compaction and cementation,that occur as sediment is transformed into rock
D)the process of breaking down a source rock into smaller pieces called grains

Question 40

Symmetric ripples form when ________.

A)wind blows in a consistent direction and deposits sediment in an arid climate
B)water flows in a consistent direction and deposits sediment in layers
C)water deposits sediment in layers,but the direction of flow periodically changes
D)a mountain stream reaches a flat basin and sediment is deposited in a fan-shaped pattern

Question 41

Which environment would most likely produce sedimentary deposits characterized by poorly to moderately sorted,angular to subangular grains that consist of feldspar,quartz,and lithics (rock fragments)?

A)river
B)glacier
C)beach
D)alluvial fan

Question 42

Death Valley is currently sinking partly due to the weight of continuously accumulating sediment shed from the mountains that border the valley.What phenomenon is this an example of and what depositional environment is created by the sediment deposition?

A)regression and deltas
B)subsidence and deltas
C)regression and alluvial fans
D)subsidence and alluvial fans

Question 43

Sea level rises locally,and marine sediments are deposited on top of terrestrial sediments during events termed ________.

A)transgressions
B)regressions
C)turbidity currents
D)cross bedding

Question 44

The image below of Death Valley,CA,shows a road that curves around a(n)________.

A)delta
B)alluvial fan
C)turbidite
D)glacial till

Question 45

A well-sorted sandstone with asymmetric ripples was most likely deposited as sand by a ________.

A)river (far from source)
B)glacier
C)river (near source)
D)alluvial fan

Question 46

Which of the following is NOT true about regressions?

A)They are not typically well preserved in the sedimentary record.
B)They can occur when the climate warms and continental ice sheets melt.
C)They occur when the land is uplifted by tectonic processes.
D)Coastal environments will migrate seaward.

Question 47

As compared with metamorphism,diagenesis ________.

A)means exactly the same thing
B)takes place at lower temperatures and pressures
C)takes place at higher temperatures and pressures
D)takes place at greater depths that are well within the mantle

Question 48

Beach sediments travel ________ the ocean during a transgression and ________ the ocean during a regression.

A)toward;away from
B)away from;toward
C)parallel to;perpendicular to
D)perpendicular to;parallel to

Question 49

Because the velocity of sediment settling (deposition)is positively related to grain size for waterborne sediments,fluvial deposits are more likely than glacial deposits to ________.

A)be well sorted
B)include coarse grains,such as cobbles
C)include fine grains,such as clay
D)have angular grains

Question 50

Pulling a block of clay apart,resulting in the middle portion thinning and sinking,is an adequate analogy for ________.

A)passive margins and subsidence
B)foreland basins and diagenesis
C)rift basins and subsidence
D)intercontinental basins and diagenesis

Question 51

What is the difference between the formation of chalk versus chert?

A)They have different grain sizes.
B)They are made of different source materials.
C)Chalk is terrestrial;chert is marine.
D)Chalk is biochemical;chert is chemical.

Question 52

Diagenesis refers to ________.

A)the development of layering within sedimentary rocks
B)the act of deposition of sediment that will ultimately form sedimentary rock
C)physical and chemical alterations,including compaction and cementation,that occur as sediment is transformed into rock
D)the natural process of separating sediment by grain size