Deck 6: Pages of Earths Past: Sedimentary Rocks

Question 1

Geologically,medium-sized sediment refers to ____________.

A) cobbles
B) pebbles
C) sand
D) silt

Answer 1

C

Question 2

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

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

Answer 2

B

Question 3

The 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

Answer 3

D

Question 4

Compaction and cementation of grains occurs during ____________.

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

Question 5

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

A) biochemical
B) clastic
C) organic

Question 6

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

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

Question 7

Sedimentary deposition is a continuous process; rivers,lakes,and the ocean deposit sediments nonstop at a fairly constant rate.

Question 8

Of the grains above,which possesses greater sphericity?

A) grain A
B) grain B
C) Neither, both grains possess approximately equal sphericity.

Question 9

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 10

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

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

Question 11

As compared to arkose,quartz sandstone ____________.

A) is more mature
B) does not contain significant amounts of feldspar
C) is likely to be found farther away from weathering granitic source rock
D) all of the above

Question 12

Which transport medium carries the largest particles?

A) ice
B) water
C) wind

Question 13

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

A) deposition
B) erosion
C) weathering

Question 14

Grains become rounded primarily during ____________.

A) weathering at outcrop
B) erosion
C) transportation
D) deposition

Question 15

If water is the transport medium 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

Question 16

A clastic rock comprised 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) graywacke
D) arkose

Question 17

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

A) ice
B) water
C) wind

Question 18

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 19

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

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

Question 20

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

A) deposition
B) erosion
C) weathering

Question 21

Bedding refers to ____________.

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

Question 22

Physically precipitated (chemical)limestone that forms in caves is termed ____________.

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

Question 23

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

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

Question 24

The thickest sequences of sedimentary rocks are typically found in ____________.

A) the oceans, beside the mid-ocean ridges
B) the interior of the largest continents
C) sedimentary basins, broad depressions that catch sediment
D) mountain belts, broad areas where rock and sediment are uplifted

Question 25

Diagenesis refers to ____________.

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

Question 26

Finding mudstone,chalk,and chert together at outcrops suggests that the ancient environment represented was ____________.

A) a delta
B) shallow marine
C) deep marine
D) a lake

Question 27

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

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

Question 28

The smallest detrital grains are ____________.

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

Question 29

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 30

Unlike physically precipitated chert,biochemical chert ____________.

A) is bedded (layered)
B) is made up of the skeletons of radiolaria and foraminifera
C) does not occur as small nodules within bodies of limestone
D) all of the above

Question 31

Most sorting of detrital grains takes place during ____________.

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

Question 32

A well-sorted sandstone with asymmetric ripples was most likely deposited as sand ____________.

A) in a river bed
B) by a glacier
C) on a beach
D) in an alluvial fan

Question 33

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 34

A sandstone with a large proportion of feldspar due to the physical weathering of granite is more precisely termed a(n)____________.

A) arkose
B) breccia
C) greywacke
D) wacke

Question 35

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

A) regressions
B) transgressions
C) divarications

Question 36

Which type of sediment settles at greater fluid velocities than sand?

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

Question 37

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 38

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 39

Of the grains above,which is more rounded?

A) grain A
B) grain B
C) Neither, both grains possess approximately equal roundness.