Deck 13: Groundwater

Question 1

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

Answer 1

Stalactites are dripstone formations shaped like icicles that hang from the roof of a cave.Stalagmites are dripstone formations that project upward from the floor of a cave.They form in pairs because they are from the same dripping source,and the two may continue growing until they merge.

Question 2

What is hard water? How is it found,and what are its negative effects?

Answer 2

Hard water contains dissolved calcium and magnesium ions.It is found primarily in areas that are underlain by carbonate rocks.The ions precipitate in water pipes,water heaters,and even on glasses and dishes.

Question 3

Briefly explain the role of streams in the formation of caverns,and the process by which several levels of vertically connected caves may form.

Answer 3

Water can percolate into limestone bedrock and cavern systems from surface streams.Streams may connect with a cavern system and disappear beneath the ground.Fluctuating rainfall levels can cause fluctuating groundwater levels,thus forming cavern systems at different depths.

Question 4

What are the most common sources of groundwater contamination?

Question 5

What is one method that can be used in the construction of a landfill which will make it less likely to contaminate groundwater? Why is this done?

Question 6

What are the health effects of drinking water with high concentrations of arsenic?

Question 7

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

Question 8

What is karst topography?

Question 9

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

Question 10

What causes the subsidence that sometimes accompanies groundwater use?

Question 11

What factors affect the surface configuration of the water table in an area?

Question 12

What are the three major uses for groundwater?

Question 13

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

Question 14

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

Question 15

Why are porosity and permeability important when considering groundwater?

Question 16

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

Question 17

Briefly explain why the artesian-pressure surface slopes.

Question 18

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 19

Contrast porosity and permeability.

Question 20

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

Question 21

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

Question 22

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

Question 23

A stream that just disappears has flowed ____________________.

Question 24

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

Question 25

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

Question 26

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

Question 27

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

Question 28

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

Question 29

The Leaning Tower of Pisa leans largely because of ____________________.

Question 30

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

Question 31

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

Question 32

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

Question 33

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

Question 34

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

Question 35

What factors contribute to the high degree of local variability in the amount of groundwater arsenic?

Question 36

During times of drought,the water table ____________________.

Question 37

Groundwater is one reservoir of the ____________________ cycle.

Question 38

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

Question 39

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

Question 40

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

Question 41

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 42

What conditions are needed for the development of karst topography?

A) humid climate
B) arid climate
C) carbonate bedrock at a shallow depth
D) humid climate and carbonate bedrock at a shallow depth
E) all of these

Question 43

The maximum level of arsenic permitted in drinking water by the U.S.Environmental Protection Agency is

A) 10 parts per million
B) 10%
C) 0.010 parts per million
D) 1%

Question 44

An example of a rock/sediment type which could be an effective aquiclude is ____.

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

Question 45

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

Question 46

What is the general term for deposits of calcite and/or aragonite within caves?

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

Question 47

What is the heat source for hydrothermal activity on land?

A) earthquake faults
B) recent or current volcanic activity
C) deep heat in Earth's interior
D) earthquake faults and recent or current volcanic activity
E) recent or current volcanic activity and deep heat in Earth's interior

Question 48

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

Question 49

What is the average rate of groundwater flow?

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

Question 50

Rocks such as limestone,granite,and gneiss cannot be groundwater reservoirs.

Question 51

Most detrital rocks are neither porous nor permeable.

Question 52

Which of the following is most permeable?

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

Question 53

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

Question 54

States in which there is extensive karst topography include which of the following?

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 55

Groundwater in an aquifer is sometimes called fossil water because

A) the water has been in the aquifer for thousands of years.
B) the water is not being replenished at anywhere near the same rate as when it formed.
C) tiny microorganisms living in the aquifer are living fossils.
D) the water has been in the aquifer for a long time and is not being rapidly replenished.

Question 56

What is a natural fountain that intermittently ejects hot water and steam into the air?

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

Question 57

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 58

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 intersects the ground surface

Question 59

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

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

Question 60

Which of the following is most porous?

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

Question 61

Caves do not form in marble because it is a dense and hard rock.

Question 62

Saltwater incursion occurs primarily along coastlines.

Question 63

In hilly country,the groundwater table's highest elevation occurs in stream valleys and around lakes.

Question 64

The zone of saturation extends to an indefinite depth.

Question 65

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