Weathering, Erosion, Weathering, Erosion, and Plate Tectonicsand Plate Tectonics

The creation of Earth’s FaceThe creation of Earth’s Face

QuestionsQuestions

►What forces and phenomena create What forces and phenomena create the different features of the earth?the different features of the earth?

►What are tectonic plates?What are tectonic plates?►What are the three major Types of What are the three major Types of

Plate Boundaries?Plate Boundaries?►What are the two external processes What are the two external processes

that change the earth’s surface?that change the earth’s surface?►What are the different types of What are the different types of

Weathering and Erosion?Weathering and Erosion?

Forces that change the Earth’s Forces that change the Earth’s SurfaceSurface

►There are two major geological There are two major geological processes that create features on the processes that create features on the earth:earth: Faulting and Plate TectonicsFaulting and Plate Tectonics Weathering and ErosionWeathering and Erosion

►They both take a long time to change They both take a long time to change the earth.the earth.

►Remember, nothing drastic on earth Remember, nothing drastic on earth happens at human speeds.happens at human speeds.

Plate TectonicsPlate Tectonics

►Huge volumes of heated and molten Huge volumes of heated and molten rock moving around the earth’s rock moving around the earth’s interior form massive solid plates that interior form massive solid plates that move extremely slowly across the move extremely slowly across the earth’s surface.earth’s surface. Tectonic platesTectonic plates: huge rigid plates that : huge rigid plates that

are moved with convection cells or are moved with convection cells or currents by floating on currents by floating on magmamagma or molten or molten rock.rock.

The Earth’s Major Tectonic The Earth’s Major Tectonic PlatesPlates

Figure 15-4Figure 15-4

The Earth’s Major Tectonic The Earth’s Major Tectonic PlatesPlates

►The extremely slow movements of these The extremely slow movements of these plates cause them to grind into one another plates cause them to grind into one another at at convergent plate boundariesconvergent plate boundaries, move , move apart at apart at divergent plate boundariesdivergent plate boundaries and and slide past at slide past at transform plate boundariestransform plate boundaries..

Figure 15-4Figure 15-4

Fig. 15-4, p. 338

Fig. 15-4a, p. 338

EURASIAN PLATEEURASIAN PLATENORTH NORTH AMERICAN AMERICAN PLATEPLATE

ANATOLIAN ANATOLIAN PLATEPLATE

JUAN DE JUAN DE FUCA PLATEFUCA PLATE

CHINA CHINA SUBPLATESUBPLATE

CARIBBEAN CARIBBEAN PLATEPLATE

PHILIPPINE PHILIPPINE PLATEPLATE

ARABIAN ARABIAN PLATEPLATEAFRICAN AFRICAN

PLATEPLATEPACIFIC PACIFIC PLATEPLATE SOUTH SOUTH

AMERICAN AMERICAN PLATEPLATENAZCA NAZCA

PLATEPLATEINDIA-INDIA-

AUSTRALIAN AUSTRALIAN PLATEPLATE

SOMALIAN SOMALIAN SUBPLATESUBPLATE

ANTARCTIC PLATEANTARCTIC PLATE

Divergent plate boundaries

Convergent plate boundaries

Transform faults

Fig. 15-4b, p. 338

Trench Volcanic island arc Craton

Transform fault

LithosphereSubduction zone

Lithosphere Lithosphere

Asthenosphere Asthenosphere Asthenosphere

Divergent plate boundaries Convergent plate boundaries Transform faults

Rising magma

GEOLOGIC PROCESSESGEOLOGIC PROCESSES

►The San The San Andreas Fault Andreas Fault is an example is an example of a of a transform transform fault.fault.

Figure 15-5Figure 15-5

Wearing Down and Building Wearing Down and Building Up the Earth’s SurfaceUp the Earth’s Surface

►Weathering Weathering is an is an external external process process that wears that wears the earth’s the earth’s surface surface down.down.

Figure 15-6Figure 15-6

WeatheringWeathering

► Three types of weathering:Three types of weathering: PhysicalPhysical

► Big Rock becomes Small Rock due to wind, rain, and Big Rock becomes Small Rock due to wind, rain, and frost wedging.frost wedging.

► Frost wedging occurs when water freezes in between Frost wedging occurs when water freezes in between the pores of large sedimentary rocks.the pores of large sedimentary rocks.

ChemicalChemical► When a chemical reaction degrades or decompose rock.When a chemical reaction degrades or decompose rock.► More common with rocks containing carbon and More common with rocks containing carbon and

oxygen, like limestone.oxygen, like limestone. BiologicalBiological

► Conversion of Rock and Minerals into smaller particles Conversion of Rock and Minerals into smaller particles due to living thing.due to living thing.

► Lichens, Tree Roots, Earthworms.Lichens, Tree Roots, Earthworms.

Fig. 15-6, p. 340

Parent material (rock)

Biological weathering (tree roots and lichens)

Chemical weathering (water, acids, and gases)

Physical weathering (wind, rain, thermal expansion and contraction, water freezing)

Particles of parent material

ErosionErosion

►Erosion is another major external factor Erosion is another major external factor that changes the surface of the earth.that changes the surface of the earth.

►Erosion is different from weathering Erosion is different from weathering because erosion deposits materials because erosion deposits materials from one place to another.from one place to another.

►Two major examples of erosion:Two major examples of erosion: Glacial Movement and MeltGlacial Movement and Melt Mass WastingMass Wasting

Glacial Movement and Mass Glacial Movement and Mass WastingWasting

► Glacial MovementGlacial Movement The Movement of Glaciers grind away The Movement of Glaciers grind away

mountainsides and form basins to capture mountainsides and form basins to capture melted ice watermelted ice water

The Great Lakes were formed using this method.The Great Lakes were formed using this method.► Mass WastingMass Wasting

When Rock and soil masses become detached When Rock and soil masses become detached from underlying material and move downhill from underlying material and move downhill under the influence of gravity.under the influence of gravity.

► Rockslides, Mudslides, and LandslidesRockslides, Mudslides, and Landslides Clearing of Trees and other vegetation increase Clearing of Trees and other vegetation increase

Mass Wasting Occurrences. Mass Wasting Occurrences.