Question 1

Which one of the following is not a chemical sedimentary rock or evaporite?
A)shale
B)bedded gypsum
C)oolitic limestone
D)cherty dolostone

Accepted Answer

Shale is a clastic sedimentary rock, composed of mud that is a mix of flakes of clay minerals and tiny fragments of other minerals, especially quartz and calcite. It is not a chemical sedimentary rock or evaporite, which are formed by the precipitation of minerals from water solutions.

Question 2

What is the chemical formula for dolomite, the major mineral in dolostones?
A)SiO2
B)CaSO4 · 2H2O
C)CaMg(CO3)2
D)NaCl

Accepted Answer

Dolomite is a mineral composed of calcium magnesium carbonate with the chemical formula CaMg(CO3)2.

Question 3

Which of the following sedimentary rocks would you expect to have originally been deposited by fast- moving streams?
A)mudstone
B)greywacke
C)conglomerate
D)oolitic limestone

Accepted Answer

Conglomerate is a sedimentary rock that consists of rounded to angular fragments larger than 2 mm in diameter. These fragments are usually cemented together by finer-grained material such as sand and clay. Conglomerates are commonly associated with fast-moving streams and rivers where larger sediments can be transported due to the velocity of the water.

Question 4

_______, a common mineral found in igneous rocks, is the most abundant mineral in detrital sedimentary rocks.
A)Orthoclase
B)Calcite
C)Quartz
D)Biotite

Accepted Answer

Quartz is the most abundant mineral in detrital sedimentary rocks. It is a common mineral found in igneous rocks and is resistant to weathering, which allows it to survive the erosion process and become a part of sedimentary rocks. Orthoclase, biotite, and calcite are also common minerals found in igneous rocks but they are not as abundant in detrital sedimentary rocks as quartz.

Question 5

Which characteristic is absolutely necessary for a sedimentary rock to have potential as a possible reservoir rock for oil or gas?
A)high permeability
B)good stratification
C)chemical origin
D)clastic texture

Accepted Answer

High permeability is necessary to allow for the movement and storage of oil and gas in the rock. A good stratification may be helpful for identifying the rock layers, but it is not necessary for it to have potential as a reservoir rock. A chemical origin or clastic texture do not have a direct correlation with the potential for a rock to be a reservoir.

Question 6

Which of the following is not a type of limestone?
A)coquina
B)travertine
C)chalk
D)arkose

Accepted Answer

Darkose is a type of sandstone, not limestone. Coquina, travertine, and chalk are all types of limestone.

Question 7

Which major component of detrital sedimentary rocks only rarely occurs as a primary mineral in igneous rocks?
A)clays
B)quartz
C)carbonates
D)ferromagnesian minerals

Accepted Answer

Clays are formed from the weathering and erosion of pre-existing rocks, and are not commonly formed as primary minerals in igneous rocks. In contrast, quartz is a common primary mineral in many igneous rocks, such as granite, while carbonates and ferromagnesian minerals can also be primary minerals in some igneous rocks.

Question 8

Nonclastic textures are common in which of the following sedimentary rocks?
A)cherty conglomerates
B)boulder breccias
C)sandstones
D)limestones

Accepted Answer

Nonclastic textures are textures that are not composed of fragments or grains that have been cemented together, but rather are made up of chemical or organic material that has precipitated or accumulated. Limestones are the most common example of nonclastic sedimentary rocks, as they are formed from the accumulation of calcium carbonate shells and skeletons of marine organisms. Cherty conglomerates (A) and boulder breccias (B) are both clastic rocks, formed from the cementation of rock fragments. Sandstones (C) can be either clastic or nonclastic, depending on their composition and mode of formation.

Question 9

_______are further concentrated in a residual brine after NaCl is crystallized.
A)Potassium, magnesium, and bromine
B)Magnesium, calcium, and sulfur
C)Calcium, sulfur, and titanium
D)Iron, sodium, and chlorine

Accepted Answer

Potassium, magnesium, and bromine are commonly found in seawater and are further concentrated in the residual brine after the crystallization of sodium chloride (NaCl). This brine is often used for the production of other chemicals, such as potassium chloride and magnesium chloride.

Question 10

A cherty limestone would contain which major constituents?
A)silica, iron oxide
B)clay minerals
C)iron oxide, calcite
D)silica, calcite

Accepted Answer

Cherty limestone is composed of significant amounts of silica and calcite. So, option D (silica, calcite) is the correct answer. The other options do not include the major constituents of cherty limestone.

Question 11

_______cement produces bright- red and yellow colors in some sandstone.
A)Clay
B)Iron oxide
C)Calcite
D)Quartz

Accepted Answer

Iron oxide is responsible for the bright-red and yellow colors in sandstone.

Question 12

What is probably the single most important, original, depositional feature in sedimentary rocks?
A)sizes of the sand grains
B)bedding or stratification
C)compaction of the mud and clay
D)degree of lithification

Accepted Answer

Bedding, also known as stratification, is a result of the layering of sedimentary rocks during the deposition process. It provides important information about the environment of deposition and can be used to determine the direction and rate of sedimentary deposition. The other options may also be important in sedimentary rocks, but bedding/stratification is the most definitive feature that distinguishes sedimentary rocks from other rock types.

Question 13

A graywacke is_______ .
A)a sandstone with the sand grains embedded in a clay- rich matrix
B)a dark, organic- rich, chemical sedimentary rock containing small crystals of halite
C)a dark- gray, calcite- rich mudstone or shale containing pyrite
D)a limestone with abundant, sand- sized, quartz grains

Accepted Answer

A graywacke is a type of sandstone that has sand grains embedded in a clay-rich matrix. It is typically dark gray in color and has a gritty texture. This type of rock is commonly found in areas where there has been significant tectonic activity and is often associated with submarine fans and turbidites.

Question 14

Sedimentary rocks account for about what percentage of the Earth's outermost 10 kilometers of rock (first percentage). Also, what percentage of the Earth's continental area is covered by sedimentary rocks (second percentage)?
A)3.5% and 100%
B)85% and 100%
C)65% and 10%
D)5% and 75%

Accepted Answer

Sedimentary rocks account for about 5% of the Earth's outermost 10 kilometers of rock, but they cover about 75% of the Earth's continental area. This discrepancy is because sedimentary rocks are often found in layers at the Earth's surface, especially on continents where they can be more easily studied and observed.

Question 15

_______is a form of calcium carbonate.
A)Lignite
B)Chert
C)Travertine
D)Gypsum

Accepted Answer

Travertine is a form of calcium carbonate that is formed from the accumulation of carbonate minerals in limestone caves or hot springs.

Question 16

Oolitic limestone is most likely to form in what type of depositional environment?
A)deep, marine waters below most wave action
B)shallow, clear, marine waters with vigorous current activity
C)acidic, organic- rich waters in freshwater swamps and bogs
D)quiet, muddy, lagoons and bays

Accepted Answer

Oolitic limestone is usually formed in shallow, clear, marine waters with vigorous current activity. These vigorous currents create a high-energy environment where tiny spherical grains (oolites) form through the accumulation and cementation of calcium carbonate around shell fragments or other tiny particles. This process is known as oolitization.

Question 17

Which of the following sedimentary features would typically be found in shales but not in sandstones?
A)bedding
B)mud cracks
C)cross stratification
D)ripple marks

Accepted Answer

Mud cracks are formed when wet sediment dries and shrinks, causing cracks to form. This is more commonly found in shales, which are composed of fine-grained sediment that can retain water and easily dry out, as opposed to sandstones, which are coarser-grained and typically do not retain as much water. Bedding, cross stratification, and ripple marks are all sedimentary features that can be found in both shales and sandstones.

Question 18

Detrital grains of which mineral(s)are extremely rare in detrital sediments? Why?
A)Feldspars; they occur only in granites.
B)Calcite; it is soft and relatively soluble.
C)Clays; they are rare in soils and regolith.
D)Quartz; it is very hard and insoluble.

Accepted Answer

Calcite is soft and relatively soluble, making it rare in detrital sediments.

Question 19

Which statement concerning sedimentary rocks is NOT true?
A)They may contain fossils that provide clues about ancient life forms.
B)They are composed of particles and constituents derived from weathering and erosion of other rocks.
C)They were originally deposited at depth below the bottom of the sea.
D)They probably show some evidence of stratification.

Accepted Answer

Sedimentary rocks may be deposited in a variety of environments, including oceans, lakes, rivers, and even on land. Some may form at great depths, but not necessarily always below the bottom of the sea.

Question 20

_______is the most common type of chemical sedimentary rock.
A)Limestone
B)Quartz sandstone
C)Chert
D)Phosphate rock

Accepted Answer

Limestone is the most common type of chemical sedimentary rock, formed from the precipitation of calcite or aragonite. Quartz sandstone and chert are examples of siliceous sedimentary rocks, and phosphate rock is a type of organic sedimentary rock formed from the accumulation of organic remains.

Quiz 7: Sedimentary Rocks

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

What is the chemical formula for dolomite, the major mineral in dolostones?

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

_______, a common mineral found in igneous rocks, is the most abundant mineral in detrital sedimentary rocks.

Which characteristic is absolutely necessary for a sedimentary rock to have potential as a possible reservoir rock for oil or gas?

Which of the following is not a type of limestone?

Which major component of detrital sedimentary rocks only rarely occurs as a primary mineral in igneous rocks?

Nonclastic textures are common in which of the following sedimentary rocks?

_______are further concentrated in a residual brine after NaCl is crystallized.

A cherty limestone would contain which major constituents?

_______cement produces bright- red and yellow colors in some sandstone.

What is probably the single most important, original, depositional feature in sedimentary rocks?

A graywacke is_______ .

Sedimentary rocks account for about what percentage of the Earth's outermost 10 kilometers of rock (first percentage) . Also, what percentage of the Earth's continental area is covered by sedimentary rocks (second percentage) ?

_______is a form of calcium carbonate.

Oolitic limestone is most likely to form in what type of depositional environment?

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

Detrital grains of which mineral(s) are extremely rare in detrital sediments? Why?

Which statement concerning sedimentary rocks is NOT true?

_______is the most common type of chemical sedimentary rock.