Holt Science & Technology Earth Science H1

1. Earth Science: Book H, Chapter 1

2. Section 1: The Active River
By the end of this section, you should be able to:
 Describe how moving water shapes the surface of
the Earth by the process of erosion.
 Explain how water moves through the water cycle.
 Describe a watershed.
 Explain three factors that affect the rate of stream
erosion.
 Identify four ways that rivers are described.

3. Erosion
 Erosion is the process by which soil and sediment
are transported from one location to another.
 Water is a major agent of erosion. Rivers often
carry eroded materials long distances.

4. Water Cycle
 The water cycle is the continuous movement of
Earth’s water from the ocean to the atmosphere to
the land and back to the ocean.
 The water cycle is driven by energy from the sun.

7. River Systems
 A stream that flows into a lake or into a larger
stream is called a tributary.
 A watershed, or drainage basin, is the area of land
that is drained by a water system.

8.  Watersheds are separated from each other by
areas of higher ground called divides.

9. Stream Erosion
 As a stream forms, it erodes rock and soil to create
a channel. The channel is the path that the stream
follows.
 Streams start out with narrow and steep channels.
Over time the channels become wider and deeper.
 When streams become longer and wider, they are
called rivers.

10. Stream Erosion
 Gradient is the measure of the change in elevation
over a certain distance.

11. Calculating a Stream’s Gradient
Math Practice on p.7

12. Stream Erosion
 The amount of water that a stream or river carries
in a given amount of time is called discharge.

13. Stream Erosion
 The materials carried by a stream are called the
stream’s load.

14. Stages of a River
 A youthful river erodes its channel deeper rather
than wider. These rivers have steep gradients, few
tributaries, and can include rapids and waterfalls.
 A mature river erodes its channel wider rather than
deeper. They have gradients that are not as steep
with fewer falls and rapids. Mature rivers do have
more discharge than a youthful river.

15. Stages of a River
 An old river has a low gradient and little erosive
energy. These rivers deposit rock and soil in and
along its channel. They also have wide, flat flood
plains and many bends.
 Rejuvenated rivers are found where the land is
raised by tectonic activity.

16. Section Review
p.11 #2-6, 9-10

17. Warmup
Even though flooding along rivers is potentially
harmful, many farms are located near rivers.
Why do people build farms along rivers?

18. Section 2: Stream & River Deposits
By the end of this section, you should be able to:
 Describe the four different types of stream
deposits.
 Describe how the deposition of sediment affects
the land.

19. Deposition in Water
 Rivers can act as a type of liquid conveyor belt to
carry fertile soil to farmland and wetlands.
 After rivers erode soil and rock they deposit their
load downstream.
 The rock and soil deposited by streams is called
sediment.
 Deposition is the process in which material is laid
down or dropped.

20. Deposition in Water
 Heavy minerals are sometimes deposited at places
in a river where the current slows down.
 This kind of sediment is called a placer deposit.

21. Deposition in Water
 As its current slows, a river often deposits its load
in a fan-shaped pattern called a delta.
 A delta is made mostly of mud and these mud
deposits form new land and cause the coastline to
grow.

22. Deposition on Land
 Fast-moving mountain streams slow down very
quickly when they flow onto a flat plain.
 These streams deposit their sediment in a fan-
shape called an alluvial fan. These deposits form
on dry land.

23. Think/Pair/Share
 Compare and contrast deltas and alluvial fans.
 Where is sediment deposited?

24. Deposition on Land
 The area along a river that forms from sediment
deposited when a river overflows its banks is called
a floodplain.
 Floodplains contain rich farmland due to the
periodic flooding that brings new soil to the land.

25. Deposition on Land
 Floods can damage property and cause a loss of
lives. Dams and levees are often used to prevent
flooding.

27. Section Review
p.15 #2-7

28. Modeling Watersheds Lab
 How does water get into a river?
 Water always flows ____________?

31. Warmup
A family lives 50 km from the nearest
stream or lake and gets water from a well.
Where does the water in the well come
from?

32. Section 3: Water Underground
By the end of this section, you should be able to:
 Identify and describe the location of the water
table.
 Describe an aquifer.
 Explain the difference between a spring and a well.
 Explain how caves and sinkholes form as a result of
erosion and deposition.

33. Water Underground
 Groundwater is the water located within the rocks
below the Earth’s surface.
 It not only is an important resource but it plays an
important role in erosion and deposition.

34. Location of Groundwater
 The zone of aeration and the zone of saturation
meet at a boundary known as the water table.

35. Aquifers
 An aquifer is a body of rock or sediment that
stores groundwater and allows the flow of
groundwater.

37. Did You Know?
 Geologists estimate that aquifers hold 50 million
cubic kilometers of fresh water worldwide.
 There is about 20 times more water underground
than in the atmosphere and all of the rivers and
lakes combined.

38. Aquifers
 The percentage of open space between individual
rocks is called porosity.
 Porosity depends on the differences in sizes of the
particles that make up the rock layers.
 A rock’s ability to let water pass through is called
permeability.
 The larger the particles, the more permeable the
rock layer is due to less friction.

40. Aquifers
 The best aquifers usually form in permeable
materials.
 The ground surface where water enters an aquifer
is called the recharge zone.
 The size of the recharge zone depends on the
permeability of the surface.

41. Water Conservation
In the United States, water use has been reduced
15% over the last 20 years.
How do you think this has happened?

42. Springs and Wells
 A spring is where the water table has reached
Earth’s surface and water is flowing out of the
ground.
Springs can be important sources of what?

43. Springs and Wells
 In areas where the water table is higher than
Earth’s surface, a lake will form.

44. Springs and Wells
 An artesian spring is a spring whose water flows
from a crack in the cap rock of an aquifer.

45. Springs and Wells
 A human-made hole that is deeper than the level
of the water table is called a well.

47. Underground Erosion & Deposition
 Groundwater can cause erosion by dissolving rock.
 Although caves are formed by erosion, they also
show signs of deposition, such as stalactites and
stalagmites.

48. Underground Erosion & Deposition
 When the water table lowers, the roofs of caves
are no longer supported by the water underneath.
The roof of a cave can then collapse, which leaves
a circular depression called a sinkhole.

49. Section Review
p.21 #2-11

50. Warmup
While hiking, you realize your water bottle
is almost empty.
Why should you not fill your bottle with
water from the nearest stream?

51. Section 4: Using Water Wisely
By the end of this section, you should be able to:
 Identify two forms of water pollution.
 Explain how the properties of water influence the
health of a water system.
 Describe two ways that wastewater can be treated.
 Describe how water is used and how water can be
conserved in industry, in agriculture, and at home.

52. Our Fresh Water
 Our bodies are almost 65% water.
 Only 3% of Earth’s water is drinkable.
 Of that 3%, 75% is frozen in the polar ice caps.
 WE MUST PROTECT OUR WATER RESOURCES!

53. Water Pollution
 Pollution is the introduction of harmful substances
into the environment.
 Pollution that comes from one specific site is called
point-source pollution.
 Nonpoint-source pollution is pollution that comes
from many sources.

55. Health of a Water System
 Fish and other organisms that live in water need
dissolved oxygen in the water to live.
 Elevated nitrate levels in water can be harmful to
organisms because they lower the amount of
dissolved oxygen in the water.
 Alkalinity refers to water’s ability to neutralize acid.
Acid rain can lower water’s alkalinity.

56. Cleaning Polluted Water
Where does our waste water go?
 Sewage treatment plants are facilities that clean
the waste materials out of water.
 They also protect the environment from water
pollution and protect us from diseases that could
be easily transmitted through dirty water.

57. Cleaning Polluted Water
 In primary treatment, dirty water is passed through
a large screen to catch solid objects.
 In secondary treatment, the water is sent to an
aeration tank, where it is mixed with oxygen and
bacteria.

59. Cleaning Polluted Water
 A septic tank is a large underground tank that
cleans wastewater from a household.

60. Where the Water Goes
 About 19% of water used in the world is used for
industrial purposes.
 Water must be used in agriculture to facilitate
plant growth.
 Many people save water by installing low-flow
shower heads and low-flush toilets.

61. How Do You Use Water?
 The average household in the United States uses
about 100 gallons of water per day.

62. Section Review
p.27 #2-9, 11