Download Hewitt/Lyons/Suchocki/Yeh, Conceptual Integrated Science

Hewitt/Lyons/Suchocki/Yeh
Conceptual Integrated
Science
Chapter 24
EARTH’S SURFACE—
LAND AND WATER
Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley
This lecture will help you
understand:
• A survey of Earth’s landforms
• Folds and faults and how they are
classified
• The different types of mountains
• The topography of the ocean floor
• Earth’s water and where it is found
• The different erosive agents that sculpt
Earth’s surface
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Earth’s Many Landforms
Earth consists of seven continents:
Africa, Antarctica, Asia, Australia,
Europe, North America, and South
America
Continental elevations vary between
• Mt. Everest (8848 m)
• Dead Sea shores (–400 m)
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Earth’s Many Landforms
Earth has three oceans:
The Pacific Ocean
• Largest, deepest, and oldest
The Atlantic Ocean
• Coldest and saltiest
The Indian Ocean
• Smallest
BUT, the oceans are all connected
• In reality, there is just one big ocean.
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Earth’s Many Landforms
Continental land features
• High mountains, plateaus, lowland plains
Ocean features
• Deep trenches to mid-ocean ridge system
Tectonic force and landforms
• Folds, faults, mountains
Erosive force and landforms
• Valleys, canyons, deltas, and floodplains
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Crustal Deformation
Deformation is a general term that refers
to all changes from the original form
and/or size of a rock body.
Most crustal deformation occurs along
plate margins.
How rocks deform:
• Rocks subjected to stresses begin to
deform.
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Crustal Deformation
Compressional stress—convergent plate
boundary
• Pushing together of rock masses
Tensional stress—divergent plate
boundary
• Pulling apart of rock masses
Shear stress—transform fault-plate
boundary
• Rock masses sliding past one another
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Crustal Deformation
Elastic deformation
• Size and shape deform, but rock returns to
original form when stress is removed
Fracture
• Elastic limit of rock exceeded; rock breaks
• Colder, surface rock
Plastic deformation
• Elastic limit of rock exceeded; shape
changed permanently—folds
• Warmer, subsurface rock
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Folds
During crustal deformation, rocks are
often bent into a series of wave-like
undulations called folds.
Characteristics of folds:
• Most folds result from compressional
stresses that shorten and thicken the crust.
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Folds
• Anticlines—upfolded or arch-shaped rock
layers.
• Oldest rock layers at the fold core, rock layers get
younger away from core.
• Synclines—downfolds or trough-shaped rock
layers.
• Youngest rocks at the fold core, rock layers get
older away from the core.
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Faults
“Strength” of rock exceeded
• Faults are fractures with displacement.
• Sudden fault movement causes most
earthquakes.
• Faults classified by relative
displacement
—Dip-slip (vertical), strike-slip (horizontal),
or oblique
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Dip-Slip Faults
Dip-slip fault movement is up or down
• Footwall—rock below the fault surface
where a miner could stand.
• Hanging wall—rock above the fault surface
where a miner could hang a lamp.
Normal fault: hanging wall moves down
relative to footwall—tension
Reverse fault: hanging wall moves up
relative to footwall—compression
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Dip-Slip Faults
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Strike-Slip Faults
Displacement is horizontal, right-lateral, or
left-lateral depending on direction of
movement.
Facing the fault:
• Block on opposite side of fault moves to
the right (right-lateral)
• Block on opposite side of fault moves to
the left (left-lateral)
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Strike-Slip Faults
Transform fault-plate boundary:
• Large strike-slip fault that cuts through
the lithosphere, accommodates motion
between two tectonic plates
• San Andreas Fault zone—major
transform fault separating Pacific Plate
and North American Plate
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Strike-Slip Faults
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Oblique-Slip Faults
Faults with combined motion:
• Move horizontally as in a strike-slip
fault
• Move vertically as in a dip-slip fault
• Oblique faulting occurs when
tensional and shear forces or
compressional and shear forces exist.
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Crustal Deformation
CHECK YOUR NEIGHBOR
Rocks begin to deform when they
A.
B.
C.
D.
become subjected to folding and faulting.
are subjected to compressional, tensional, or shear forces.
break.
undergo partial melting.
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Crustal Deformation
CHECK YOUR ANSWER
Rocks begin to deform when they
A.
B.
C.
D.
become subjected to folding and faulting.
are subjected to compressional, tensional, or shear forces.
break.
undergo partial melting.
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Crustal Deformation
CHECK YOUR NEIGHBOR
Rocks deform and fold in response to
A.
B.
C.
D.
tensional forces that elongate the crust.
tensional forces that shorten the crust.
compressional forces that elongate the crust.
compressional forces that shorten the crust.
Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley
Crustal Deformation
CHECK YOUR ANSWER
Rocks deform and fold in response to
A.
B.
C.
D.
tensional forces that elongate the crust.
tensional forces that shorten the crust.
compressional forces that elongate the crust.
compressional forces that shorten the crust.
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Crustal Deformation
CHECK YOUR NEIGHBOR
A normal fault is created as rock in the hanging wall
A.
B.
C.
D.
drops down relative to rocks in the footwall. Tension pulls the rock
apart.
drops down relative to rocks in the footwall. Tension pushes the
rock together.
moves up relative to rocks in the footwall. Compression pulls the
rock apart.
moves up relative to rocks in the footwall. Compression pushes
the rock together.
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Crustal Deformation
CHECK YOUR ANSWER
A normal fault is created as rock in the hanging wall
A.
B.
C.
D.
drops down relative to rocks in the footwall. Tension pulls
the rock apart.
drops down relative to rocks in the footwall. Tension pushes the
rock together.
moves up relative to rocks in the footwall. Compression pulls the
rock apart.
moves up relative to rocks in the footwall. Compression pushes
the rock together.
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Crustal Deformation
CHECK YOUR NEIGHBOR
A reverse fault is created as rock in the hanging wall
A.
B.
C.
D.
drops down relative to rocks in the footwall. Tension pulls the rock
apart.
drops down relative to rocks in the footwall. Tension pushes the
rock together.
moves up relative to rocks in the footwall. Compression pulls the
rock apart.
moves up relative to rocks in the footwall. Compression pushes
the rock together.
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Crustal Deformation
CHECK YOUR ANSWER
A reverse fault is created as rock in the hanging wall
A.
B.
C.
D.
drops down relative to rocks in the footwall. Tension pulls the rock
apart.
drops down relative to rocks in the footwall. Tension pushes the
rock together.
moves up relative to rocks in the footwall. Compression pulls the
rock apart.
moves up relative to rocks in the footwall. Compression
pushes the rock together.
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Mountains
Mountains are thick sections of crust
elevated with respect to the surrounding
crust.
Mountains are classified according to their
structural features:
• Folded Mountains
• Upwarped Mountains
• Fault-Block Mountains
• Volcanic Mountains
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Folded Mountains
Mountains mostly occur at convergent
plate boundaries—crustal thickening
causes uplift.
• Compression folds, thickens, and
shortens the crust—isostatic uplift
Continental collision creates highest
mountains
• Himalayas—India and Eurasia
• Appalachians—North America and Africa
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Upwarped Mountains
Broad upwarping of deeper rock deforms
overlying sedimentary rock, producing
roughly circular structures—domes.
• Older rocks are in the center, and younger
rocks are on the flanks.
• The Black Hills of South Dakota are a large,
domed structure generated by upwarping.
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Fault-Block Mountains
• Fault-block mountains occur within large
areas of broad uplift.
• Overall force is usually compression.
• But crust is also stretched in such settings,
like a balloon is stretched when inflated.
• Another example: When a tree branch is
bent, compression occurs on the inside of
the bend and tension occurs on the outside
of the bend.
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Fault-Block Mountains
Normal faults in stretched crust let huge blocks drop
downward. Block left standing is the mountain. Broad
uplift continues.
• The Sierra Nevada Mountains
• The Grand Teton Mountains
• The Basin and Range Province
— The Great Basin, geographically
— Covers most of Nevada and parts of Arizona, California,
and Utah
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Volcanic Mountains
Volcanic mountains formed by eruptions
of lava, ash, and rock fragments.
Opening at the summit of a volcano:
• Crater: steep-walled depression at the
summit, less than 1 km in diameter
• Caldera: summit depression greater
than 1 km diameter, produced by
collapse following a massive eruption
Vent—an opening connected to the
magma chamber via a pipe
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Volcanic Mountains
Shield volcano:
•
•
•
•
Broad, large, slightly dome-shaped volcano
Composed primarily of basaltic lava
Mild eruptions of large volumes of lava
Mauna Loa on Hawaii
Cinder cone:
• Ejected lava (mainly cinder-sized) fragments
• Steep slope angle, small in size
• Sunset Crater in Arizona
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Volcanic Mountains
Composite cone:
• Large, classic-shaped volcano (thousands
of feet high and several miles wide at
base)
• Composed of interbedded lava flows and
alternating layers of ash, cinder, and mud
• Many are located adjacent to the Pacific
Ocean (Mount Fuji, Mount St. Helens)
• Very violent, explosive volcanic activity (Mt.
Vesuvius)
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Volcanic Mountains
Most volcanoes form near plate boundaries
where converging plates meet.
About 75% of the world’s volcanoes are found
in the “Ring of Fire” that encircles the Pacific
Ocean.
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Volcanic Mountains
Hot spots—stationary, deep, very hot. Hot
mantle rock moves upward by convection.
Hot spot volcanism:
• Partial melting occurs near the surface
• Localized volcanism in the overriding plate
• In oceanic crust, basaltic magma produced—
Hawaiian Islands
• In continental crust, granitic magma
produced—Yellowstone National Park
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Mountains
CHECK YOUR NEIGHBOR
Mountains are generally formed
A.
B.
C.
D.
E.
along convergent plate boundaries.
by tectonic forces.
where continents collide.
where uplift results from crustal thickening.
all of the above.
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Mountains
CHECK YOUR ANSWER
Mountains are generally formed
A.
B.
C.
D.
E.
along convergent plate boundaries.
by tectonic forces.
where continents collide.
where uplift results from crustal thickening.
all of the above.
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Mountains
CHECK YOUR NEIGHBOR
Weathering and erosion wears mountains down, but many
mountains continue to maintain their lofty stature because
A.
B.
C.
D.
of isostatic convergence.
the rate of uplift counters the rate of erosion.
magma pushes them upward at a faster rate than erosion wears
them down.
tensional forces in subduction zones continue to operate and
push rock upward.
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Mountains
CHECK YOUR ANSWER
Weathering and erosion wears mountains down, but many
mountains continue to maintain their lofty stature because
A.
B.
C.
D.
of isostatic convergence.
the rate of uplift counters the rate of erosion.
magma pushes them upward at a faster rate than erosion wears
them down.
tensional forces in subduction zones continue to operate and
push rock upward.
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Mountains
CHECK YOUR NEIGHBOR
Most of the world’s volcanoes are formed around the “Ring
of Fire” because
A.
B.
C.
D.
of seafloor spreading in the Pacific Plate.
the Pacific Plate is surrounded by subduction zones and
associated convergent boundaries.
the Pacific Ocean floor is very thin, and magma plumes are very
close to the surface.
it burns, burns, burns.
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Mountains
CHECK YOUR ANSWER
Most of the world’s volcanoes are formed around the “Ring
of Fire” because
A.
B.
C.
D.
of seafloor spreading in the Pacific Plate.
the Pacific Plate is surrounded by subduction zones and
associated convergent boundaries.
the Pacific Ocean floor is very thin, and magma plumes are very
close to the surface.
it burns, burns, burns.
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Earth’s Waters
Earth is 71% covered by water: ~97% is
saltwater in the oceans; ~3% is fresh water.
• ~2% is frozen in ice caps and glaciers.
• ~1% is liquid fresh water in groundwater, and
water in rivers, streams, and lakes.
• A small amount is water vapor.
Earth’s waters are constantly circulating. The
driving forces are:
• Heat from the Sun
• Force of gravity
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Earth’s Waters
The hydrologic cycle is the set of processes that
controls the circulation of water on Earth.
Processes involved in the hydrologic cycle:
•
•
•
•
Evaporation
Precipitation
Infiltration
Runoff
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Earth’s Waters
Water that goes from the ocean back to
the ocean completes a hydrologic cycle.
The journey is not always direct, and
water can flow as:
• Streams, rivers, and groundwater
• Water can also be frozen in ice caps and
glaciers
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The Ocean Floor
Ocean floor encompasses continental
margins and deep ocean basins.
Continental margins are between
shorelines and deep ocean basins.
• Continental shelf—shallow; underwater
extension of the continent.
• Continental slope—marks boundary
between continental and oceanic crust.
• Continental rise—wedge of accumulated
sediment at base of continental slope.
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The Ocean Floor
The ocean bottom is not flat, it is etched
with deep canyons, trenches, crevasses.
Underwater mountains rise upward from
the seafloor.
The deep-ocean basin:
• Basalt from seafloor spreading plus thick
accumulations of sediment
• Abyssal plains, ocean trenches, and
seamounts
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The Ocean Floor
The deep-ocean basin:
• Abyssal plains—flattest part of the ocean floor due
to accumulated sediment
• Ocean trenches—long, deep, steep troughs at
subduction zones
• Seamounts—elevated seafloor from volcanism
Mid-ocean ridges:
• Sites of seafloor spreading (volcanic and tectonic
activity)
• A global mid-ocean ridge system winds all around
the Earth
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The Ocean Floor
The deepest parts of the ocean are at the
ocean trenches near some of the
continents.
The shallowest waters are in the middle of
the oceans around underwater
mountains (mid-ocean ridge system).
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The Ocean
CHECK YOUR NEIGHBOR
Ocean trenches are the deepest parts of the ocean floor
because
A.
B.
C.
D.
that is where oceanic crust meets continental crust.
that is where subduction occurs.
no sediment accumulates in trenches.
all accumulated sediment settles in the abyssal plain.
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The Ocean
CHECK YOUR ANSWER
Ocean trenches are the deepest parts of the ocean floor
because
A.
B.
C.
D.
that is where oceanic crust meets continental crust.
that is where subduction occurs.
no sediment accumulates in trenches.
all accumulated sediment settles in the abyssal plain.
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Ocean Waves
Characteristics of waves—waves get their
energy from the wind.
• The crest is the peak of the wave.
• The trough is the low area between waves.
• Wave height is the distance between a trough
and a crest.
• Wavelength is the horizontal distance between
crests.
• Wave period is the time interval between the
passage of two successive crests.
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Ocean Waves
Height, length, and period of a wave
depend on:
• Wind speed
• Length of time wind has blown
• Fetch—the distance that the wind has
traveled across open water
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Ocean Waves
Wave of oscillation:
• Wave energy moves forward, not water
• Occurs in the open sea in deep water
Wave of translation:
• Shallow water; depth about one-half wavelength—wave
begins to “feel bottom”
• Wave grows higher as it slows and wavelength shortens
• Steep wave front collapses, wave breaks
• Turbulent water goes up the shore and forms surf
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Ocean Waves
CHECK YOUR NEIGHBOR
When a wave approaches the shore, the water depth
decreases. This affects the wave by flattening its circular
motion,
A.
B.
C.
D.
decreasing its speed, and increasing distance between waves
and wave height.
increasing its speed and distance between waves, and
decreasing wave period.
decreasing its speed and distance between waves, causing wave
height to increase.
increasing its speed and distance between waves, causing wave
height to increase.
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Ocean Waves
CHECK YOUR ANSWER
When a wave approaches the shore, the water depth
decreases. This affects the wave by flattening its circular
motion,
A.
B.
C.
D.
decreasing its speed, and increasing distance between waves
and wave height.
increasing its speed and distance between waves, and
decreasing wave period.
decreasing its speed and distance between waves, causing
wave height to increase.
increasing its speed and distance between waves, causing wave
height to increase.
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Ocean Water
Ocean water is a complex solution of mineral salts,
dissolved gases, and decomposed biological
material.
Salinity: the proportion of salts to pure water.
• ~35 grams salts per 1000 grams of water
Salinity and temperature control density
• Salty, cold water is denser than less salty, warmer
water
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Ocean Water
Salinity is variable:
Salinity decreases as fresh water enters
the ocean:
• Runoff from streams and rivers
• Precipitation
• Melting of glacial ice
Salinity increases as fresh water leaves
the ocean:
• Evaporation
• Formation of sea ice
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Ocean Water
CHECK YOUR NEIGHBOR
The density of seawater is controlled by
A.
B.
C.
D.
salinity.
temperature and salinity.
pressure and salinity.
sea ice and runoff.
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Ocean Water
CHECK YOUR ANSWER
The density of seawater is controlled by
A.
B.
C.
D.
salinity.
temperature and salinity.
pressure and salinity.
sea ice and runoff.
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Ocean Water
CHECK YOUR NEIGHBOR
The salinity and, hence, density of seawater increase by
A.
B.
C.
D.
evaporation and precipitation.
evaporation and formation of ice.
evaporation, runoff, and melting of sea ice.
runoff, precipitation, and melting of glacial ice.
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Ocean Water
CHECK YOUR ANSWER
The salinity and, hence, density of seawater increase by
A.
B.
C.
D.
evaporation and precipitation.
evaporation and formation of ice.
evaporation, runoff, and melting of sea ice.
runoff, precipitation, and melting of glacial ice.
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Earth’s Fresh Water
Only ~3% of Earth’s water is “fresh.”
Of the 3%,
~85% is frozen in ice sheets and glaciers
~14% is groundwater
~0.8% is in lakes and reservoirs, soil
moisture, and rivers
~0.04% is water vapor
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Surface Water
Surface water includes streams, rivers,
lakes, and reservoirs.
Infiltration of water is controlled by:
•
•
•
•
•
Intensity and duration of precipitation
Prior wetness condition of the soil
Soil type
Slope of the land
Nature of the vegetative cover
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Surface Water
The land area that contributes water to a stream
is called the drainage basin.
Drainage basins are separated by drainage
divides.
The largest drainage divides are continental
divides.
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Groundwater
Water beneath the ground exists as
groundwater and soil moisture.
Groundwater occurs in the saturated
zone—water has filled all pore spaces.
Soil moisture is above the saturated zone
in the unsaturated zone—pores filled
with water and air.
The water table is the boundary between
these two zones.
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Groundwater
The depth of the water table varies with
precipitation and climate.
• Zero in marshes and swamps, hundreds of
meters in some deserts.
• At perennial lakes and streams, the water
table is above the land surface.
• The water table tends to rise and fall with the
surface topography.
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Groundwater
Factors that influence storage and
movement of groundwater:
• Porosity: ratio of open space in soil, sediment,
or rock to total volume of solids plus voids—
the amount of open space underground.
• Greater porosity equals more potential to
store greater amounts of groundwater.
• Particle size, shape, and sorting influence
porosity.
— Soil with rounded particles of similar size has
higher porosity than soil with various sizes.
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Groundwater
Permeability
• Degree to which groundwater can flow
through a porous material—higher
permeability, greater potential for fluid flow.
• Sediment packing and connectedness of
pores influences permeability—example of
clay and sandstone:
— Both have high porosity, but clay’s small, flattened
sediment grains makes for tighter packing and
smaller pores. Water cannot flow easily through
small pores— so clay has low permeability.
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Groundwater
CHECK YOUR NEIGHBOR
A soil with rounded particles of similar size will have a
higher porosity than a soil with rounded particles of various
sizes, because
A.
B.
C.
D.
it will have a higher permeability.
water flows more easily through rounded particles.
smaller sediment grains will fill the open pore spaces between
larger grains.
poorly sorted sediment will have more open pore spaces.
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Groundwater
CHECK YOUR ANSWER
A soil with rounded particles of similar size will have a
higher porosity than a soil with rounded particles of various
sizes, because
A.
B.
C.
D.
it will have a higher permeability.
water flows more easily through rounded particles.
smaller sediment grains will fill the open pore spaces
between larger grains.
poorly sorted sediment will have more open pore spaces.
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Groundwater
Aquifers are reservoirs of groundwater.
Aquifers generally have high porosity and high
permeability.
Aquifers underlie the land surface in many areas; they
are a vital source of fresh water.
It is important to keep this vital source of fresh water
clean and contaminant free.
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Surface Processes
• Earth’s surface is worn away by the
processes of erosion.
• Agents of erosion include:
•
•
•
•
Gravity
Water
Wind
Ice
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The Work of Gravity
Mass movement—the downslope movement of
Earth material (rock, soil, debris, land), due to
gravity.
Rapid movement:
• Debris avalanche, rock fall, rock slide, landslide,
debris flow
• Evidence: concave scars, debris, buried structures
Slow movement:
• Soil creep, rock slump
• Evidence: broken retaining walls, bent tree trunks
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The Work of Surface Water
Running water shapes Earth’s surface in two
opposing ways: fast water transports sediment,
slow water deposits sediment.
Streamflow—two types of flow; stream speed
• Laminar flow—slow and gentle
• Turbulent flow—fast and rapid
Factors that determine velocity:
• Gradient, or slope
• Channel characteristics (shape and size)
• Discharge—volume of water moving past a given
point in a certain amount of time
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The Work of Surface Water
Stream erosion:
• Loosely consolidated particles are lifted by
abrasion and dissolution.
Stronger currents lift particles more effectively:
• Stronger currents have “higher” energy
• Lift and transport more and bigger particles
• Turbulent versus laminar flow
Downward limit to stream erosion:
• The lowest point to which a stream can erode is
called base level.
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The Work of Surface Water
Two general types of base level:
•
•
•
•
Ultimate (sea level)
Local or temporary (lake, etc.)
Raising base level causes deposition
Lowering base level causes erosion
Transportation of sediment by streams:
• Capacity: maximum load a stream can transport—
controlled by stream discharge
• Competence: maximum particle size a stream can
transport— controlled by stream velocity
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The Work of Surface Water
Decreased velocity causes sediment
deposition—competence and capacity
reduced, sediment drops out of flow.
Stream sediments (alluvium) are generally well
sorted.
• Natural levees—form parallel to stream channel
by successive floods
• Alluvial fans develop where a high-gradient
stream abruptly leaves a narrow valley
• Deltas form when stream enters an ocean, bay,
or lake—creates new land
Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley
The Work of Surface Water
CHECK YOUR NEIGHBOR
As a river flows down to lower elevations, stream velocity
A.
B.
C.
D.
increases, capacity and competence decrease.
decreases, causing capacity and competence to decrease.
decreases, and capacity and competence increase.
increases as it forms a delta.
Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley
The Work of Surface Water
CHECK YOUR ANSWER
As a river flows down to lower elevations, stream velocity
A.
B.
C.
D.
increases, capacity and competence decrease.
decreases, causing capacity and competence to decrease.
decreases, and capacity and competence increase.
increases as it forms a delta.
Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley
The Work of Groundwater
Flowing groundwater can alter and
change features at the surface:
• Land subsidence
• Caves and caverns
• Sinkholes
Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley
The Work of Groundwater
Land Subsidence:
• Extreme groundwater withdrawal
by pumping from wells can result
in lowering of the land—land
subsidence.
• Land subsidence is especially
prevalent in aquifers made of
sandy sediments and interbedded
clays. The clays leak water to the
sand, then when water is pumped
out, the clays shrink and compact,
causing subsidence.
Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley
The Work of Groundwater
Caverns and caves
• The dissolving action of groundwater “eats
away” at rock—limestone in particular.
• Rainwater chemically reacts with CO2 in
the air and soil, producing carbonic acid.
The acidified water seeps into rock
(especially limestone), partially dissolving
it.
• Such action has carved out magnificent
caves and caverns (a cavern is a large
cave).
Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley
The Work of Groundwater
Sinkholes are funnel-shaped cavities in
the ground that are open to the sky;
they are formed similar to caves. They
can also be formed from conditions of
drought and the over withdrawal of
groundwater.
Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley
The Work of Wind
Wind blows everywhere, but its impact on
sculpting the land is minor.
Impact is greatest where:
• Strong winds blow frequently
• Vegetation is sparse or absent
— Plant roots keep particles together
— Plants deflect wind and shelter particles
• Surface particles are small
— Small particles are more easily lifted and
transported
Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley
The Work of Glaciers
Glaciers are powerful agents of erosion. A
glacier is like a plow as it scrapes and
plucks up rock and sediment.
Glaciers are also powerful agents of
deposition. A glacier is like a sled as it
carries its heavy load to distant places.
Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley
The Work of Glaciers
A glacier is an accumulation of snow and ice
thick enough to move under its own weight.
• Two types of glaciers:
— Alpine
— Continental
• Alpine glaciers develop in mountainous areas,
generally confined to individual valleys.
— Cascades, Rockies, Andes, Alps, Himalayas
— Erosional landforms: cirque, arête, horn, hanging
valley, U-shaped valley
Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley
The Work of Glaciers
Continental Glaciers:
• Spread over large areas
—Antarctica, Greenland, Alaska
• Erosional landforms
—Roches moutonees, striations
• Depositional landforms
—Moraine, kame, esker, drumlin
Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley
Surface Processes
CHECK YOUR NEIGHBOR
There are many erosive agents that sculpt Earth’s surface.
Overall, the erosive agent that does the most work is
A.
B.
C.
D.
wind.
groundwater.
running water.
glaciers.
Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley
Surface Processes
CHECK YOUR ANSWER
There are many erosive agents that sculpt Earth’s surface.
Overall, the erosive agent that does the most work is
A.
B.
C.
D.
wind.
groundwater.
running water.
glaciers.
Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley