Deck 7: Sedimentary Environments

Question 1

Mountain streams and rivers typically are characterized by:

A) steep gradients and are confined by bedrock canyons
B) low gradients and unconfined channels
C) steep gradients and unconfined channels
D) low gradients and are confined by bedrock canyons

Answer 1

A

Question 2

What is the geologic setting of Vancouver, British Columbia?

A) it is surrounded by low-lying hills
B) it is along the Fraser River and its delta
C) it is on a large but scenic island in the ocean
D) it is on a large but scenic island in a lake
E) none of these

Answer 2

B

Question 3

Melting glaciers tend to deposit most of the sediment they carry and create:

A) at their terminus end)
B) downhill but underneath the glacier
C) in situ in the place of creation)

Answer 3

A

Question 4

Which of the following environments would most likely have sediment formed by evaporation of seawater?

A) beach at A
B) lagoon at B
C) coral reef at C
D) deep seafloor at D
E) tidal flat at E

Question 5

Which of the following sites would have the slowest moving or least energetic current?

A) mountain streams at A
B) glacial streams at B
C) braided river at C
D) delta at D
E) lake at E

Question 6

Fluvial refers to:

A) the processes and sediment of streams and rivers
B) the movement of fluids underground
C) the hydrological cycle on land

Question 7

Most of the exposed surface of the Earth is covered with:

A) sediment and sedimentary rocks
B) sediment and igneous rocks
C) sediment and metamorphic rocks

Question 8

The largest sand dunes in dry climates can stretch:

A) hundreds of kilometers
B) hundreds of meters
C) tens of meters

Question 9

Which of the following sites would have sand and silt deposited by slowing of the current?

A) mountains at A
B) glacial streams at B
C) braided river at C
D) delta at D
E) lake at E

Question 10

What happens to the majority of sediment being carried by moving water as it enters a standing body little or no motion) of water?

A) The sediment gradually settles to the bottom.
B) The sediment remains suspended.
C) The sediment dissolves in the water column.

Question 11

Which of the following sites would most likely have turbidity currents?

A) beach at A
B) lagoon at B
C) coral reef at C
D) deep seafloor at D
E) tidal flat at E

Question 12

Large, angular clasts are most likely at:

A) mountains at A and glaciers at B
B) glaciers at B and braided river at C
C) braided river at C and delta at D
D) delta at D and lake at E

Question 13

Sediments with a large amount of sand are most likely at:

A) mountains at A and glaciers at B
B) glaciers at B and braided river at C
C) braided river at C and delta at D
D) delta at D and lake at E

Question 14

What sedimentary environments dominate the area around Vancouver, British Columbia?

A) deposition of sediment carried by a braided river
B) large landslides that blocked a narrow ocean channel
C) large ocean waves that carry large boulders far inland
D) a scenic offshore reef that protects the coastline from large waves

Question 15

Lithifies can be defined as:

A) loose sediment hardens into sedimentary rock
B) loose sediment breaks off of sedimentary rocks
C) sediment settles from the water column

Question 16

The two main processes by which sediment is produced are:

A) physical and chemical weathering
B) subduction and melting
C) transportation and deposition

Question 17

Sedimentary environments on land differ because of variations in:

A) topography
B) local geology
C) amount of water
D) all of these

Question 18

Which of the following sites would contain the finest grained sedimentary deposits?

A) mountains at A
B) glaciers at B
C) braided river at C
D) delta at D
E) lake at E

Question 19

Which of the following environments would most likely form limestone?

A) beach at A
B) lagoon at B
C) coral reef at C
D) deep seafloor at D
E) tidal flat at E

Question 20

Which of the following environments would most likely consist of sand and/or rounded cobbles?

A) beach at A
B) lagoon at B
C) coral reef at C
D) deep seafloor at D
E) tidal flat at E

Question 21

The deep-sea floor is characterized by sediment dominated by:

A) fine dust and the remains of single-celled organisms
B) silt and sand derived from rivers and streams
C) calcite mud and other material derived from coral reefs

Question 22

Downslope marine flows comprised of mixed masses of sand, mud, and water are called:

A) turbidity currents
B) longshore currents
C) tidal currents

Question 23

Which of the following processes is NOT considered physical weathering?

A) near-surface fracturing
B) frost wedging
C) prying by plant roots
D) thermal expansion
E) oxidation

Question 24

What type of weathering is best expressed in this weathered limestone?

A) oxidation
B) dissolution
C) hydrolysis
D) biologic activity

Question 25

What is the best explanation for the shape of these clasts?

A) they are composed of relatively soft, soluble materials
B) they accumulated on a steep slope
C) they have been moved by the wind and rounded by blowing sand in sand dunes
D) they have been transported a significant distance

Question 26

Which of the following attributes does NOT apply to these sediments?

A) angular clasts
B) cobbles and boulders
C) well sorted
D) composed of gravel

Question 27

In warm, shallow, marine environments, corals and other marine life typically construct:

A) reefs
B) stromatolites
C) tidal flats

Question 28

If you were designing a rock that resisted weathering, which of the following characteristics would it have?

A) closely spaced fractures
B) a soluble chemical composition
C) a quartz-rich rock
D) a rock composed of abundant loose pieces

Question 29

Rocks rich in what mineral tend to have a poor solubility during weathering?

A) quartz
B) calcite
C) halite
D) anhydrite

Question 30

What typically happens to the size, shape, and sorting of clasts as they are transported from steep mountains toward more gentle settings?

A) the size of the clasts increases
B) the clasts become more rounded
C) the sediment becomes more poorly sorted
D) all of these

Question 31

Which of the following processes is NOT considered to be chemical weathering?

A) dissolution
B) thermal expansion
C) oxidation
D) hydrolysis
E) reaction with acids from decaying plants

Question 32

Shallow coastal accumulations of sand that rise above the sea as long, narrow islands are called:

A) barrier islands
B) fringing islands
C) sand islands

Question 33

Which of the following environments would likely have clasts smaller than sand?

A) a weak current
B) steep slopes
C) dunes formed by wind
D) all of these

Question 34

Sedimentary rocks are comprised of material that comes primarily from:

A) other locations
B) the ground below
C) the same place the rock forms

Question 35

Which of the following situations would result in angular clasts?

A) transport of the clasts over long distance
B) working of clasts by waves on a beach
C) steep slopes in a mountain
D) dunes formed by wind

Question 36

Fine-grained sediment would most likely be present at:

A) the beach at A and lagoon at B
B) the lagoon at B and coral reef at C
C) the coral reef at C and deep seafloor at D
D) the beach at A and coral reef at C
E) the lagoon at B and deep seafloor at D

Question 37

Compared to non-fractured rocks, the rate of weathering in fractured rocks of the same composition is:

A) faster
B) slower
C) roughly the same

Question 38

Which of the following processes produce sedimentary clasts?

A) fracturing of bedrock that results in angular pieces
B) breaking of round cobbles as they are transported
C) scouring and abrasion of bedrock along rivers
D) decomposition of granite into quartz grains and clay
E) all of these

Question 39

The effect of transportation on a pebble's particle size is best summarized by which statement?

A) Its size decreases.
B) Its size stays the same.
C) Its size increases.

Question 40

If you were designing a rock that would be easily weathered, which of the following characteristics would it have?

A) closely spaced fractures
B) a soluble chemical composition
C) a limestone in a wet climate
D) a rock composed of abundant pieces
E) all of these

Question 41

Sorting describes:

A) the size range of clasts in sediment
B) the general shape of the clasts in the sediment
C) the layering in the sediment

Question 42

What type of rock is shown in this photograph?

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

Question 43

Which of the following is NOT a common type of cement in sedimentary rocks?

A) calcite
B) pyroxene
C) silica
D) iron-oxide minerals

Question 44

If a rock is poorly sorted, this means the rock contains:

A) mostly sand
B) a great variety of rock types as clasts
C) some angular and some rounded clasts
D) some parts that are reddish and others that are not
E) a wide range in the size of clasts

Question 45

Which of the following environments would likely have large clasts?

A) a weak current
B) steep slopes
C) dunes formed by wind
D) all of these

Question 46

Sedimentary clasts are:

A) loose fragments of rocks and minerals
B) deposits of sand in a lens shape
C) small sedimentary basins along a river or stream

Question 47

What type of rock is shown in this photograph?

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

Question 48

Identify the factors) that strongly influence the size, shape, and/or sorting of sedimentary clasts.

A) Steepness of slope
B) Sediment supply
C) Strength of current
D) Agents of transport
E) All of these

Question 49

What type of rock is shown in this photograph?

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

Question 50

What is the main difference between conglomerate and breccia?

A) the size of the clasts
B) the shape of the clasts
C) the sorting of the clasts
D) the kind of cement
E) all of these

Question 51

Which of the following statements is NOT true about clastic sedimentary rocks?

A) Clasts in a conglomerate or breccia can be different rock types or can be all the same rock type.
B) To be called a sandstone, quartz must make up more than 95 percent of the grains.
C) The amount of pore space decreases as a sand is compacted into sandstone.
D) Siltstone is coarser than shale.

Question 52

Which of the following is NOT involved in turning some sediment into sedimentary rock?

A) burial
B) compaction
C) cementation
D) metamorphism
E) all of these are involved

Question 53

What type of rock is shown in this photograph?

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

Question 54

Which of the following rocks is composed of the smallest sedimentary clasts?

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

Question 55

The uniformly-sized sand shown here would be described as:

A) well sorted
B) poorly sorted
C) not sorted
D) moderately sorted

Question 56

What type of rock would you form in this environment, showing a dried up lake bed?

A) rock salt and other evaporite minerals
B) limestone
C) coal
D) chert
E) iron formation

Question 57

Which of the following characteristics are NOT used to classify and name clastic sediments?

A) the size of the clasts
B) the amount of sorting of clasts
C) the shape of the clasts
D) the climate in which the clasts are produced
E) all of these are used

Question 58

The rock shown here, with sediment just visible to the naked eye, is a:

A) sandstone
B) shale
C) conglomerate

Question 59

The natural cements that hold clasts together precipitate in the empty pore spaces after compaction. Those precipitates come from:

A) water containing dissolved materials
B) outward growth of the original clasts
C) the alignment of clay particles

Question 60

Clastic sedimentary rocks are classified primarily on the basis of:

A) sediment size
B) depth of burial
C) sedimentary structures
D) location of these sediments

Question 61

Which of the following does NOT correctly match a rock with a possible environment in which that rock forms?

A) salt - evaporation of water
B) gypsum - evaporation of water
C) coal - deep-sea organic-rich black shale
D) chert - accumulation of tiny silica-rich creatures
E) chert - mixing of seawater and groundwater

Question 62

Gradational boundaries between different sedimentary rock types can form from:

A) slowing of the current over time
B) a progressive change from one environment to another
C) a gradual rise or fall in sea level
D) all of these

Question 63

How does chalk form?

A) evaporation of water in a lake or sea
B) accumulation of microscopic organisms composed of calcium carbonate
C) precipitation from seawater early in Earth's history
D) accumulation of silica-rich organisms or mixing of seawater and groundwater

Question 64

This photograph shows chalk. How is it formed?

A) evaporation of water in a lake or sea
B) accumulation of microscopic organisms composed of calcium carbonate
C) precipitation from seawater early in Earth's history
D) accumulation of silica-rich organisms or mixing of seawater and groundwater

Question 65

A soft, very fine-grained limestone formed via the accumulation of the calcium carbonate remains of microorganisms is known as:

A) chalk
B) gypsum
C) chert
D) dolostone

Question 66

What can you infer from this contact between an overlying conglomerate and underlying sandstone?

A) The conglomerate was deposited by the wind.
B) There was a gradual switch from marine to nonmarine conditions.
C) There was a gradual switch from nonmarine to marine conditions.
D) There was an abrupt event, such as a flood.

Question 67

What type of rock would you form in this coral reef?

A) rock salt and other evaporite minerals
B) limestone
C) coal
D) chert
E) iron formation

Question 68

Which of the following does NOT help define layers in some sedimentary rocks?

A) a change in mineral composition
B) a change in grain size
C) a change in color
D) a sharp contact between two rock types
E) all of these are ways that can define layers in sedimentary rocks

Question 69

What type of rock would you form in this plant-rich swamp?

A) rock salt and other evaporite minerals
B) limestone
C) coal
D) chert
E) iron formation

Question 70

How does gypsum form?

A) evaporation of water in a lake or sea
B) accumulation of microscopic organisms composed of calcium carbonate
C) precipitation from seawater early in Earth's history
D) accumulation of silica-rich organisms or mixing of seawater and groundwater

Question 71

This photograph shows chert. How does it form?

A) evaporation of water in a lake or sea
B) accumulation of microscopic organisms composed of calcium carbonate
C) precipitation from seawater early in Earth's history
D) accumulation of silica-rich organisms or mixing of seawater and groundwater

Question 72

Which way was the current either wind or water) moving during deposition of this section of rocks?

A) toward the left
B) toward the camera
C) toward the right
D) away from the camera
E) there is no way to tell

Question 73

How does a graded bed form?

A) an abrupt change in the composition of the sediment
B) a gradual decrease in the strength of the current over time
C) piling of sediment down the front of a dune or ripple
D) a gradual change in the climate of the region
E) a gradual change in global climate

Question 74

The large cross beds in these rocks indicate that the sediment was deposited:

A) deep in the ocean
B) in a lake with a gently sloping bottom
C) by the wind or a water current
D) by a debris flow
E) all of these

Question 75

Which of the following is NOT a way to form layers in a sedimentary rock?

A) occurrence of a discrete event like a flood
B) a change in the strength of the current
C) a change in the supply of sediment
D) a change in climate of the region
E) all of these are ways to form layers

Question 76

Peat forms from the accumulation of:

A) plant material
B) shells of microorganisms
C) iron oxides

Question 77

This photograph shows an iron formation. How does it form?

A) evaporation of water in a lake or sea
B) accumulation of microscopic organisms composed of calcium carbonate
C) precipitation from seawater early in Earth's history
D) accumulation of silica-rich organisms or mixing of seawater and groundwater

Question 78

How does a cross bed form?

A) an abrupt change in the composition of the sediment
B) a gradual decrease in the strength of the current over time
C) piling of sediment down the front of a dune or ripple
D) a gradual change in the climate
E) two glaciers that cross

Question 79

How does iron formation form?

A) evaporation of water in a lake or sea
B) accumulation of microscopic organisms composed of calcium carbonate
C) precipitation from seawater early in Earth's history
D) accumulation of silica-rich organisms or mixing of seawater and groundwater

Question 80

How does chert form?

A) evaporation of water in a lake or sea
B) accumulation of microscopic organisms composed of calcium carbonate
C) precipitation from seawater early in Earth's history
D) accumulation of silica-rich organisms or mixing of seawater and groundwater