Deck 12: Groundwater

Question 1

What causes the subsidence that sometimes accompanies groundwater use?

Answer 1

As the water is withdrawn from pore spaces in poorly consolidated sedimentary materials, the water pressure between grains is reduced, the weight of the overlying materials causes the grains to pack more closely together, and the materials become compacted, resulting in subsidence of the ground.

Question 2

How are stalactites different from stalagmites? Why do they typically form in pairs and often merge to form a column?

Answer 2

Stalactites are dripstone formations shaped like icicles that hang from the roof of a cave (remember they have a "c" in the spelling therefore they hang from the ceiling). Stalagmites are dripstone formations that project upward from the floor of a cave (remember they have a "g" in the spelling therefore they originate from the ground). They form in pairs because they are from the same source and the two may continue growing until they merge.

Question 3

What methods are used to counteract saltwater incursion?

Answer 3

Recharge wells are drilled to pump freshwater back into the groundwater system. Recharge ponds may also be constructed to allow large quantities of fresh surface water to infiltrate the groundwater supply.

Question 4

Describe the features of a partially filled aquifer layer.

Question 5

Describe the flow of water from the ground into the water table and to a stream, lake, or swamp.

Question 6

How can limestone be dissolved by groundwater when it is almost insoluble in pure water?

Question 7

Discuss the artesian system that underlies South Dakota and extends to central Texas in the Dakota Sandstone.

Question 8

Why are porosity and permeability important to groundwater?

Question 9

How do landfills cause groundwater contamination? What can be done in the construction of a landfill that will make it less likely to contaminate groundwater?

Question 10

How do caves and caverns form?

Question 11

What is an artesian system? What three geologic conditions must exist for an artesian system to form?

Question 12

What are hot springs, and what are the sources of heat?

Question 13

What is a cone of depression, where is it found, and what causes it? Why can large cones of depression be a serious problem?

Question 14

What is the immediate source of the water in groundwater?

Question 15

How do septic systems work to make sewage safe for use as a water source?

Question 16

How do stalactites, stalagmites, columns, drip curtains, and travertine terraces form?

Question 17

What is karst topography? What are some of the features of karst?

Question 18

What are some possible consequences of modifications to the groundwater system caused by human usage?

Question 19

Why does the Leaning Tower of Pisa lean? Is it likely to lean so much it will someday fall over?

Question 20

Describe saltwater incursion. What methods are used to counteract saltwater incursion?

Question 21

Where do the pollutants go once they enter the groundwater reservoir?

Question 22

How does water move in the capillary fringe?

Question 23

What are the most common sources of groundwater contamination?

Question 24

Briefly explain why the artesian-pressure surface slopes.

Question 25

What are the three major uses for groundwater?

Question 26

How can granite and many other dense igneous and metamorphic rocks be groundwater reservoirs?

Question 27

Describe dripstone and how it forms.

Question 28

Briefly explain why the groundwater table does not rise fastest in areas of low elevation.

Question 29

In what ways are geysers and undersea hydrothermal vent sites similar?

Question 30

Contrast porosity and permeability.

Question 31

What happens to the water table in an aquifer if the amount of groundwater discharged naturally or withdrawn at wells is greater than the amount added from natural or artificial sources?

Question 32

What are disappearing streams?

Question 33

Under what conditions will an artesian well flow freely at the surface?

Question 34

On what factors does permeability depend?

Question 35

How are sinkholes formed?

Question 36

What is water table?

Question 37

Briefly explain how some limestone and other carbonate rocks can have high porosity and permeability.

Question 38

What are the major problems that exist with, or are related to, groundwater supply?

Question 39

What effect do water wells have on an aquifer?

Question 40

What is one of the beneficial results of movement of water within the ground?

Question 41

The addition of water to the zone of saturation is known as ____________________.

Question 42

Groundwater is one reservoir of the ____________________ cycle.

Question 43

An impermeable layer that prevents the passage of groundwater is a(n) ____________________.

Question 44

An upward-growing projection of calcite formed from water that drips from a cave's ceiling is called a(n) ____________________.

Question 45

A place where groundwater flows/seeps out of the ground is a(n) ____________________.

Question 46

The energy produced from Earth's internal heat is ____________________ energy.

Question 47

The major source of the water stored as groundwater is ____________________.

Question 48

Groundwater under high fluid pressure is called a(n) ____________________ system. It is confined by rock bodies called ____________________.

Question 49

Within the zone of saturation, groundwater flows from the region of ____________________ pressure to the region of ____________________ pressure.

Question 50

During times of drought, the water table ____________________.

Question 51

The boundary between the zone of aeration and the zone of saturation is known as the ____________________.

Question 52

Hot springs that intermittently eject hot water and steam with tremendous force are known as ____________________.

Question 53

One common, widespread sedimentary rock that is readily dissolved by groundwater is ____________________.

Question 54

A stream that just disappears has flowed into a(n) ____________________.

Question 55

A permeable layer that transports water is called a(n) ____________________.

Question 56

A very large cave or system of interconnected caves is called a(n) ____________________.

Question 57

Rounded depressions common in regions having limestone bedrock are known as ____________________.

Question 58

The percentage of open space within a rock or sediment is known as its ____________________.

Question 59

The capacity of a material for transmitting fluids is known as its ____________________.

Question 60

The water stored in the open spaces within underground rocks and unconsolidated material is called ____________________.

Question 61

In regions of moderate to high rainfall, the top of a stream is the same as the:

A) top of the zone of aeration.
B) top of the zone of saturation.
C) bottom of the aquifer.
D) bottom of the zone of aeration.
E) top of the water table.

Question 62

States in which there is extensive karst topography include:

A) Ohio, Pennsylvania, Virginia, and West Virginia.
B) Florida, Kentucky, Tennessee, Indiana, and Missouri.
C) Minnesota, Iowa, Nebraska, and Kansas.
D) Wyoming, Arizona, Colorado, and Utah.
E) Michigan, New York, and Ohio.

Question 63

The zone above the water table, in which water is absent, is the:

A) zone of aeration.
B) zone of saturation.
C) water table.
D) ground water.
E) aquifer zone.

Question 64

About 22% of all usable water in the United States comes from groundwater.

Question 65

The general term for deposits of calcite and/or aragonite within caves is:

A) stalactites.
B) stalagmites.
C) spears.
D) dripstone.
E) calcite-stone.

Question 66

By definition, the porosity of rocks/sediments consists of pore spaces between particles/grains.

Question 67

Groundwater erupting from geysers that contain dissolved calcium carbonate will form deposits of:

A) stalactites.
B) stalagmites.
C) travertine.
D) quartz.
E) sulfides.

Question 68

The average rate of groundwater flow is:

A) a few kilometers per day.
B) a few meters per day.
C) a few centimeters per day.
D) a few millimeters per day.
E) imperceptible.

Question 69

An example of a rock type that could be a good aquifer is:

A) shale.
B) quartz sandstone.
C) clay.
D) basalt.
E) marble.

Question 70

The Dakota Sandstone is threatened primarily by:

A) pollution.
B) subsidence.
C) saltwater intrusion.
D) extensive use.
E) lack of recharge.

Question 71

A natural fountain that intermittently ejects hot water and steam into the air is a(n):

A) hot spring.
B) volcano.
C) hydrothermal vent.
D) geyser.
E) aquiclude.

Question 72

Which of the following is most porous?

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

Question 73

Conditions needed for the development of karst topography include:

A) humid climate.
B) arid climate.
C) carbonate bedrock at a shallow depth.
D) humid climate AND carbonate bedrock at a shallow depth.
E) humid or arid climate AND carbonate bedrock at a shallow depth.

Question 74

An example of a rock/sediment type that could be an effective aquiclude is:

A) quartz sandstone.
B) fractured granite.
C) gravel.
D) shale.
E) mudstone.

Question 75

A local aquiclude within a larger aquifer results in a(n):

A) cone of depression.
B) perched water table.
C) artesian aquifer.
D) zone of aeration.
E) zone of saturation.

Question 76

Which of the following is most permeable?

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

Question 77

A poorly sorted porous rock/sediment is as permeable as a well-sorted porous rock/sediment.

Question 78

Where does groundwater discharge naturally?

A) only in the ocean
B) only in springs
C) only in streams
D) only in aquifers
E) wherever the groundwater table meets the ground surface

Question 79

Rocks such as limestone and granite cannot be groundwater reservoirs.

Question 80

Groundwater will move through any rock/sediment or soil that is porous.