Deck 7: Sediment and Sedimentary Rocks

Question 1

Placer deposits are surface accumulations resulting from the mixing of materials as they are transported.

Answer 1

False

Question 2

Most gravel ____.

A)is smaller than 2 mm
B)is derived from limestone
C)cannot be transported by glacial movement
D)is made up of rock fragments
E)do not contain clasts

Answer 2

is made up of rock fragments

Question 3

Sedimentary rocks are rarely encountered on Earth without digging.

Answer 3

False

Question 4

A sedimentary rock in which all the grains are about the same size can be characterized as ____.

A)cemented
B)compacted
C)cross bedded
D)graded
E)well-sorted

Question 5

Lithification of sand and gravel requires both compaction and ____.

A)aggregation
B)filtration
C)condensation
D)cementation
E)stratification

Question 6

Most limestone is of biochemical origin.

Question 7

All deposited sediments will eventually form sedimentary rocks.

Question 8

Geologists use ____ and their knowledge of present-day depositional processes to make determinations about a rock's depositional environment.

A)the principle of uniformitarianism
B)the principle of catastrophism
C)lunar geology
D)anthropology
E)archeology

Question 9

One reason that sedimentary rocks are important in deciphering Earth history is that they ____.

A)contain fossils that are rare or absent in other types of rocks
B)reveal the types of volcanoes from which they came
C)are the most common type of rock on Earth
D)are present at spreading ridges and can help determine the age of the rock present
E)are so easily examined and understood

Question 10

Microscopic crystals of silica form a hard rock called chert, which can be shaped to form sharp cutting edges.

Question 11

Sediments are classified as ____ and ____.

A)physical; chemical
B)conglomerate; breccia
C)detrital; chemical
D)conglomerate; detrital
E)clastic; particulate

Question 12

Poorly-sorted sediment has ____.

A)no sharp edges
B)restricted size range
C)similar mineral composition throughout
D)great size variation
E)little chance of becoming sedimentary rock

Question 13

Texture and geometry are usually sufficient to determine the depositional environment of a sedimentary rock.

Question 14

Tar sand is a type of sandstone in which viscous, asphalt-like hydrocarbons fill the pore spaces.

Question 15

Detrital sedimentary rocks can undergo lithification by ____.

A)precipitation
B)transpiration
C)dissolution
D)cementation
E)evaporation

Question 16

The Navajo Sandstone is a wind-blown sand deposit with large cross-beds. How would the sand of these ancient sedimentary rocks be characterized?

A)poorly sorted
B)well-sorted
C)compacted
D)poorly graded
E)cemented

Question 17

The most common and effective agent for transporting sediment is ____.

A)wind
B)waves and currents
C)glaciers
D)storms
E)running water

Question 18

Large fossils are more useful for environmental interpretations than are microfossils.

Question 19

Siltstone, mudstone, and claystone are all types of mudrock.

Question 20

A vertical sequence of transgressive and regressive facies records the rise and fall of sea level.

Question 21

Carnotite ____.

A)undergoing pressure becomes bituminous coal
B)is the source of most of the uranium used in nuclear reactors in North America
C)is never found in granitic rocks
D)rarely occurs in the presence of plant remains
E)is another name for shale

Question 22

Historically, most coal mined in the United States has been ____.

A)anthracite
B)used in steel production
C)exported to other countries
D)formed from ancient deep-sea deposits
E)from the Appalachian region

Question 23

Oil shales are ____.

A)found only in North and South America
B)useful for the kerogen that can be extracted
C)less expensive to process than are conventional oil sources
D)currently producing 15 percent of the United States' oil
E)currently producing 30 percent of the United States' oil

Question 24

Chemical sedimentary rocks can have a clastic texture or an interlocking grain texture called ____.

A)evaporitic
B)porphyritic
C)particulate
D)crystalline
E)detrital

Question 25

Hydrocarbons are formed largely from the ____.

A)remains of dinosaurs
B)carbonate rocks
C)remains of microscopic organisms
D)compression of coal deposits
E)reservoir rock

Question 26

A rock composed almost entirely of fragmented seashells is called ____.

A)coquina
B)an ooid
C)clamstone
D)marine rock
E)detrital

Question 27

Marine transgressions are created when ____.

A)rising sea levels break existing rocks apart to form new layers
B)shorelines change from placid to turbulent due to environmental changes
C)deposition occurs during a time when sea level rises and the shoreline moves inland
D)carbon levels in sea water increase
E)deposition occurs on an ocean beach and later lithifies

Question 28

A major characteristic of graded bedding is that the rock layers ____.

A)are thick and easily distinguished from each other
B)formed because turbidity currents are less dense than sediment-free water
C)contain intersecting fractures called mud cracks
D)show an upward decrease in grain size
E)are always formed in deserts

Question 29

The most common chemical sedimentary rocks are ____.

A)alkaline
B)granitic
C)carbolic
D)anthracite
E)carbonate

Question 30

Rock salt and rock gypsum are both examples of ____.

A)banded iron formations
B)biochemical sedimentary rocks
C)evaporites
D)detrital sedimentary rocks
E)carbonate rocks

Question 31

Fossils are common because ____.

A)bones are so easily preserved
B)there are so many environments that are suitable for fossilization
C)they are obvious once they are unearthed
D)so many billions of organisms lived during the past
E)fossilization takes place quickly, before decomposition progresses too far

Question 32

Wave-formed ripple marks ____.

A)tend to have symmetrical profiles
B)are good indicators of ancient current directions
C)have a gentle slope and a steep slope
D)form in undisturbed deep-sea sedimentary environments
E)form when clay-rich sediment dries and shrinks

Question 33

Detrital sedimentary rocks are ____.

A)organisms are important in its origin
B)always calcite and are formed in an alkaline environment
C)made up of interlocking mineral crystals
D)derived from parent material and usually classified by the size of their constituent particles
E)sometimes composed of small spherical grains called ooids that have a small nucleus around which concentric layers of calcite precipitate

Question 34

Calcium carbonate readily dissolves in water that ____.

A)is heated to 100^o C
B)contains a small amount of carbonic acid
C)has pH > 8
D)is turbid
E)contains dissolved sodium chloride

Question 35

Anthracite coal ____.

A)has up to 75% carbon
B)is actually a metamorphic type rock
C)is the most abundant form of coal
D)is dull-black
E)contains high amounts of volatile elements

Question 36

Conglomerate is common, but sedimentary breccia is not. Why?

A)The gravel becomes rounded very quickly during transport.
B)The gravel is so easily consolidated.
C)The conglomerate is formed in place and does not have to be transported for long distances.
D)The sedimentary breccia is composed of rare rock types.
E)Conglomerate is weathered by water, but sedimentary breccia is weathered by wind.

Question 37

Sedimentary structures ____.

A)are folded and faulted after lithification
B)are features that form as a result of physical or biological processes operating in a depositional environment
C)include fossils
D)form only in near-shore environments with large-grained particles of carbonate origin
E)are not helpful in determining a rock's origin

Question 38

Marine regression occurs when ____.

A)sea level falls with respect to a continent
B)sea level rises and the shoreline moves inland
C)marine rocks undergo deep-sea pressure and are transformed to metamorphic rocks
D)sea water mixed several different layers of sediment types
E)volatile elements go into solution in sea water and change the composition of the sedimentary rocks that are formed

Question 39

When geologists trace a layer of sediment or sedimentary rock laterally, the layers change in composition, texture, or both. These changes result from the ____.

A)metamorphosis of the constituent rocks
B)tilting of the parent rock during formation
C)abrupt disturbances of the depositional environment
D)different rates of weathering in different layers of rock
E)simultaneous operation of different processes in adjacent depositional environments

Question 40

Graded bedding forms when ____.

A)erosion degrades a portion of the sea bottom
B)sediment is deposited on a steep slope
C)turbidity currents deposit coarse and then fine sediments
D)cross-bedding erodes and re-lithifies
E)gentle wave motion moves particles toward the shoreline

Question 41

List five (5)examples of economically important sedimentary rocks and explain their importance. Imagine that two (2)rocks from your list do not exist. Generate ideas for replacing their function(s)in our economy and explain how easy or difficult this task would be.

Question 42

____________________ form when layers are arranged at an angle to the surface on which they were deposited and the layers are inclined in the direction of wind or water ____________________.

Question 43

In the accompanying figure, indicate the three (3)major depositional environments for the formation of sedimentary rock. Discuss how physical and biological processes impart distinctive characteristics to the accumulating sediment in the different environments. Illustrate with one or more examples.

Question 44

Describe strata.

Question 45

Clams, oysters, corals, and some plants make their skeletons of minerals and form ____________________ sedimentary rocks.

Question 46

The designation of sediment grain size, from largest to smallest, is gravel, sand, ____________________, and ____________________.

Question 47

By far the most common chemical sediments are ____________________ mud and grains.

Question 48

Define source rock and reservoir rock and briefly explain how each is important to hydrocarbon production.

Question 49

The steam channel, floodplain, lake, beach or deep seafloor where a sediment is laid down is known as its ____________________.

Question 50

Describe a hypothetical scenario in which a large chunk of quartz becomes the sedimentary rock called sandstone.

Question 51

How do detrital sedimentary rocks differ from chemical sedimentary rocks?

Question 52

Two processes that can create a rock from sediment are ____________________, in which grains are squeezed and water is lost, and ____________________, in which material is precipitated in pore spaces and binds grains together.

Question 53

Describe how compaction lithifies mud sediments.

Question 54

____________________ ripple marks form in response to wind or water moving in one direction.

Question 55

Peat formation is the first step in forming the biochemical sedimentary rock called coal. Briefly describe the process of peat formation.

Question 56

Along shorelines, marine ____________________and ____________________ accomplish much of the work of sediment transport and deposition.

Question 57

Two major types of sediments that may become sedimentary rocks are ____________________ and ____________________.

Question 58

Sediment becomes sedimentary rock by the process known as ____________________.