Plate Tectonics Review

Textbook pages 209-215

Tuesday, November 3rd 2015

The Earth Is a Dynamic Planet

Three major concentric zones of the earth Core: solid inner part surrounded by a

liquid Mantle: mostly solid rock Including the asthenosphere: hot, partly melted rock that flows and can be deformed like plastic

CrustContinental crust & Oceanic crust (71% of crust)

Plate tectonics are responsible for Major Features of the Earth’s Crust and Upper Mantle

The Earth beneath your feet is moving…….

Tectonic Plates: huge rigid plates move extremely slowly atop the denser mantle on hot, soft rock in the underlying asthenosphere

Convection cells: move large volumes of rock and heat in loops within the mantle like gigantic conveyer belts

Plate tectonics = movement of lithospheric plates Heat from Earth’s inner layers drives

convection currents Pushing the mantle’s soft rock up (as it

warms) and down (as it cools) like a conveyor belt

Continents have combined, separated, and recombined over millions of years (Pangaea = all landmasses were joined into a supercontinent 225 million years ago)

The Earth beneath your feet is moving…….

The Earth’s Crust Is Made Up of a Mosaic of Huge Rigid Plates: Tectonic Plates

Fig. 14-4, p. 347

EURASIAN PLATE

NORTH AMERICAN PLATE

ANATOLIAN PLATE

JUAN DE FUCA PLATE

CARIBBEAN PLATE

PHILIPPINE PLATE

CHINA SUBPLATE

AFRICAN PLATE ARABIAN PLATE INDIA

PLATEPACIFIC PLATE PACIFIC PLATECOCOS

PLATESOUTH AMERICAN PLATE

NAZCA PLATEAUSTRALIAN

PLATESOMALIAN SUBPLATE

SCOTIA PLATE

ANTARCTIC PLATE

Transform faultsDivergent plate boundaries Convergent plate boundaries

The Earth’s Major Tectonic Plates

Three types of boundaries between plates

Divergent plates – plates move apartMagma – flows up through the resulting

cracks forms new rocks (seafloor spreading)

Oceanic ridge – some ofwhich have higher peaksand deeper canyons thanearth’s continents

Three types of boundaries between plates

Convergent plates – two plates collideOceanic & Continental: oceanic plate slides

under the continental crust (subduction) Magma erupts through the surface in volcanoes

as a result of subductionContinental & Continental: crust may lift up from bothplates (uplift) to formmountainsTrench: forms at theboundary between the 2 converging plates

Creation of a Volcano

Volcanoes Release Molten Rock from the Earth’s Interior

Volcano: magma reaches the earth’s surface through a fissure (crack)Lava: magma that reaches the earth’s

surface. Debris ranging from large chunks of larva rock to glowing hot ash, liquid lava and gases such as water vapor, carbon dioxide and sulfur dioxide.

Much of the world’s volcanic activity is concentrated along the boundaries of the earth’s tectonic plates

Benefits of volcanicactivity: highly fertile soil,creates outstandinglandforms (Crater Lake, OR)

Three types of boundaries between plates

Transform fault boundary (e.g. San Andreas fault): where plates slide and grind past one another along a fault (fracture in the rock)Fault zones are where movement has

occurredMost located on the ocean floor

The San Andreas Fault as It Crosses Part of the Carrizo Plain in California, U.S.

Earthquakes Are Geological Rock-and-Roll Events

Richter scale Insignificant: <4.0Minor: 4.0–4.9Damaging: 5.0–5.9Destructive: 6.0–6.9Major: 7.0–7.9Great: >8.0

Earthquake – occur when rocks rupture (epicenter) unexpectedly along a fault (seismic activity)

Seismic waves – waves of energyMagnitude – measures the size of the earthquake as it relates to the amplitude of the energy wave & distance

Foreshocks and aftershocksPrimary effects of earthquakes: shaking, permanent vertical or horizontal displacement of the ground

Major Features and Effects of an Earthquake

Areas of Greatest Earthquake Risk in the United States

Areas of Greatest Earthquake Risk in the World

Earthquakes on the Ocean Floor Can Cause Huge Waves Called Tsunamis

Tsunami, tidal wave: generated when part of the ocean floor suddenly rises or drops. Usually occurs offshore in subduction zones.

Detection of tsunamis: by ocean buoys, pressure recorders on the ocean floor which measures changes in water pressure as the waves pass over it; data relayed via satellites tsunami warning systems

Some Parts of the Earth’s Surface Build Up and Some Wear Down Internal geologic processes

Generated by heat from the earth’s interior, generally build up the earth’s surface in the form of continental and oceanic crust including mountains and volcanoes

External geologic processesWeathering : driven directly or indirectly

by energy from the sun(mostly in the form of flowing water and wind)Physical, Chemical, and Biological

Erosion: Wind, Flowing water, Human activities

Weathering: Biological, Chemical, and Physical Processes

Earth’s Major Geological Processes and Hazards

Gigantic plates in the earth’s crust move very slowly atop the planet’s mantle, and wind and water move the matter from place to place across the earth’s surface.

Natural geological hazards such as earthquakes, tsunamis, volcanoes, and landslides can cause considerable damage.

Earth’s Rocks are Recycled……..

The three major types of rocks found in the earth’s crust — sedimentary, igneous, and metamorphic — are recycled very slowly by the process of erosion, melting, and metamorphism.

There Are Three Major Types of Rocks

Earth’s crust is composed of minerals and rocks

Three broad classes of rocks, based on formationSedimentary Igneous

Sandstone GraniteShale Lava rockDolomite Metamorphic Slate AnthraciteLignite SlateBituminous coal MarbleLeave space under each rock type for in-class and homework notes!

The Earth’s Rocks Are Recycled Very Slowly

Rock cycle: the interaction of physical and chemical processes that change rocks from one type to another. Slowest of the earth’s cyclic processes

The Life of a Rock

Sedimentary Rock

Metamorphic

Igneous

Changes are made from pressure and

heat.

Layers of sediment join

together.

Melted rock cools and hardens

Rocks become smaller, and smaller, and smaller, and smaller. . . By erosion By wind By

earthquake By floods By rain By slides By man Rocks change…………..

By earthquakes By volcanoes By heat and pressure

Weathering: the breaking up of rocks and soil into different products (clay, sand, rock fragments like pebbles & stones)

Erosion: the moving of weathered rock and soil. Weathering allows erosion to take place.

Sedimentary Rock is . . .

Rock formed when layers of small particles of shell, rock, and sand join together.

Types of Sedimentary Rocks Include…

Gypsum

Sandstone

Shale Limestone

Conglomerate

Sedimentary RocksHow They are Made

Wind and water break down the earth Bits of earth settle in lakes and rivers Layers are formed and build up Pressure and time turn the layers to rock

Metamorphic Rock is . . .

Rock that is formed when pressure and heat create changes to sedimentary or igneous rock.

Types of Metamorphic Rocks

Metamorphic RocksWhat are They?

Rocks that have changed They were once igneous or

sedimentary Pressure and heat changed the

rocks

Igneous Rock is . . .

Rock that is formed when melted rock cools and hardens.

Types of Igneous RocksGranite

Igneous RocksWhat are They?

Fire Rocks Formed underground by trapped,

cooled magma Formed above ground when

volcanoes erupt and magma cools

With your group, share your rock type posters. Take notes on each type in your notebook – including your own!

After you’ve shared, complete the Rock Cycle Activity.