Geology Unit 1: Plate Tectonics Writing about Plate Tectonic Map.

Geology Unit 1: Plate Tectonics

Writing about

Plate Tectonic Map

Word Definition IllustrationTheory of plate tectonics

the scientific theory that the Earth’s crust is divided into large moving sections called tectonic plates

Tectonic Plate the lithosphere of the earth is divided into a small number of plates which float on the asthenosphere. Most earthquakes occur along the plate boundaries

Lithosphere The rigid outer layer of the earth that is broken into tectonic plates. The lithosphere is the crust and upper mantle

Asthenosphere The partially molten layer beneath the lithosphere. This is the lubricating layer that the tectonic plates slide on.

Subduction Zone The area where one tectonic plate slides beneath another plate.

Oceanic Trench a long narrow valley on the ocean floor that runs parallel to a volcanic range. It is the surficial expression of a subduction zone.

Tsunami An unusually large sea wave produced by an undersea volcano or other disturbance

rift valley a valley formed when continental plates move apart

mid-ocean ridge a chain of underwater mountains formed where two tectonic plates move apart

Fault a fracture in the Earth’s crust where rocks on the opposite sides have been displaced from one another.

earthquake a sudden release of pressure in Earth’s crust that causes shaking on the surface

Volcano a vent in the Earth’s crust through which lava is expelled

Alfred Wegener German meteorologist who proposed the idea of continental drift

continental drift Wegener’s proposal that continents move across Earth’s surface

seafloor spreading the process by which the ocean floor forms at the mid-ocean ridge

Pangaea a large supercontinent that existed millions of years ago

Volcanoes• Erupting Volcanoes• Volcano Video Selection including the Earth at

Image: The Indonesian volcano Anak Krakatau erupts at night (credit: Getty Images/Tom Pfeiffer/VolcanoDiscovery)

Mt St Helens, 1973

The Cascade Range

The Bulge of Mt Saint Helens

May 18, 1980Eruption of Mt. St. Helens

Mt. St. HelensBefore and After

Scientists Discuss MSH

Mt St Helens Video

Mount Saint Helens

Mount Saint Helens Video

Mount Saint Helen’s EruptionMay 18, 1980

Succession Animation

1982 Mount Saint Helens Lahar

Plate Tectonic Setting of the Cascades

Cascade Subduction Zone

Oceanic Trench

Oceanic trenches are the surficial expression of

subduction zones

Mt St Helens

Mount Fuji

Mt. Fuji, Japan Vesuvius, Naples, Italy

Popocatepetl, Mexico Pinatubo, Philippines

Plate Tectonics

Most Recent Earthquakes

• http://earthquake.usgs.gov/earthquakes

The 15 Largest Earthquakes in the United States

Location Date Time UTC Magnitude

1. Prince William Sound, Alaska 1964 03 28 03:36:14.0 UTC 9.2

2. Andreanof Islands, Alaska 1957 03 09 14:22:31.9 UTC 9.1

3. Rat Islands, Alaska 1965 02 04 05:01 and 08:40 UTC 8.7

4. East of Shumagin Islands, Alaska 1938 11 10 20:18:41.2 UTC 8.2

5. New Madrid, Missouri 1811 12 16 08:15 UTC 8.1

6. Yakutat Bay, Alaska 1899 09 10 17:04 and 21:41 UTC 8.0

7. Andreanof Islands, Alaska 1986 05 07 22:47 UTC 8.0

8. New Madrid, Missouri 1812 02 07 09:45 UTC ˜8

9. Near Cape Yakataga, Alaska 1899 09 04 00:22 UTC 7.910

.Fort Tejon, California 1857 01 09 16:24 UTC 7.9

Ka'u District, Island of Hawaii 1868 04 03 02:25 UTC 7.912

.Gulf of Alaska, Alaska 1987 11 30 19:23 UTC 7.9

New Madrid, Missouri 1812 01 23 15:00 UTC 7.814

.Imperial Valley, California 1892 02 24 07:20 UTC 7.8

San Francisco, California 1906 04 18 13:12 UTC 7.8

Earthquake Preparedness

• Judge Judy

• How Earthquakes work National Geographic

Taiwan, 1999

Seattle Earthquake

• National Geographic http://youtube.com/watch?v=V0WuSCaTYI0

Tsunami Wave

Cruise Boat meets Tsunami Wave

Japanese Tsunami

National Geographic Tsunami

Tsunami Videos

• Link to before and after pictures• Indonesian Tsuanmi Video Natioanal

Geographic• Tsunami 101 National Geographic

Plate Boundaries

DivergentIceland

Mid- Atlantic Ridge

Volcanoes

Earthquakes

Mid Ocean Ridge

TransformSan Andreas

Fault, California

Earthquakes

Convergent (Subduction)

JapanMt St Helens

Volcanoes

Earthquakes

Tsunamis

Ocean Trenches

Convergent (Mountain Building)

Himalayas(Mt Everest)

Earthquakes

Mountain Building

Plate Boundaries

DivergentIceland

Mid- Atlantic Ridge

Volcanoes

Earthquakes

Mid Ocean Ridge

Fault, California

Earthquakes

JapanMt St Helens

Volcanoes

Earthquakes

Tsunamis

Ocean Trenches

Earthquakes

Mountain Building

Geology Layout

Geology Unit 1Plate Tectonics and Crustal Features

Alfred Wegener and Continental Drift

The Evidence of Plate Tectonics

The driving force of Plate Tectonics: Mantle Convection

Geology Unit 2Contouring

Topographic Maps

Topographic Map Exercise

Weathering and Erosion

Plate Tectonics• Plate Tectonics build up mountains and

weathering and erosion pull them down.

Basic Idea of Plate Tectonics

• The Earth’s surface is divided into a few large thick plates that move slowly and change in size.

• Intense geologic activity occurs at plate boundaries

Plate Boundary

Illustration

Divergent

Transform

Convergent with

Subduction

Convergent with

Continental Collision

Plate Boundary

Illustration

Divergent

Transform

Convergent with

Subduction

Convergent with

Plate Boundary

Illustration/ Notes

Divergent

Transform

Convergent with

Subduction

Convergent with

Plate Boundary

Illustration/Notes

Divergent

Transform

Convergent with

Subduction

Convergent with

Plate Boundary

Divergent

Transform

Convergent with Subduction

Convergent with

Plate Boundary

Divergent

Transform

Convergent with Subduction

Convergent with

Plate BoundariesMovementDraw arrows

Features Location Illustration

Divergent

Transform

Convergent with a Subduction Zone

Convergent with Mountain Building

Earthquake and Plate Tectonics

Lithosphere and Asthenosphere

• Oceanic Plates – Basalt – Thinner – More Dense• Continental Plates – Granite – Thicker – More Buoyant

Divergent Plate Boundaries

• Plates moving apart• Examples

– Mid-ocean ridge (Iceland sits on the Mid Atlantic Ridge)– Red Sea

Divergent Plate Boundary

Mid Ocean Ridge System

Pangaea

The Appalachians were formed as North America, Africa and Europe collide to create Pangaea 300 million years ago.

Sea Floor Spreading

East African Triple Junction

Mid Atlantic

• Hydrothermal VentsBlack and White Smokers

Spider Crab

Tube Worms

Life at the Mid-Ocean Ridge

Iceland

Plate BoundariesPlate

BoundaryMovementDraw arrows

San Andreas Fault

Transform Plate Boundary

San Andreas FaultCalifornia

Types of Convergent Plate Boundaries

• Continental Collision– Continental plates are fused– Mountain Building

• Subduction Zone– Oceanic plate subducts under

oceanic plate– Oceanic plate subducts under

continental plate– Volcanoes and large earthquakes

Convergent Plate Boundary with Collision

Convergent Boundaries

Convergent Plate Boundary with Subduction

Subduction Zone

Ring of Fire

Cascadian Subduction Zone

Ocean – Continent Convergence

San Andreas Fault

San Andreas FaultCalifornia

Plate Boundaries

DivergentIceland

Mid- Atlantic Ridge

Volcanoes Earthquakes Mid Ocean Ridge

Fault, CaliforniaHaiti

Earthquakes

JapanMt St Helens

Volcanoes Earthquakes Tsunamis Ocean Trenches

Earthquakes Mountain Building

Plate Boundaries

Divergent

Volcanoes Earthquakes Mid Ocean Ridge

Fault, California

Earthquakes

JapanMt St Helens

Volcanoes Earthquakes Tsunamis Ocean Trenches

Earthquakes Mountain Building

Plate Tectonics

• The distribution and origin of most volcanoes, earthquakes, young mountain belts and major sea-floor features can be explained by plate tectonics

Divergent EarthquakesFissure

VolcanoesMid-Ocean

RidgeRift Valley

Mid-Atlantic RidgeIceland

Transform Earthquakes San Andreas Fault California

ConvergentSubduction

VolcanoesEarthquakesTsunamisOceanic Trench

JapanMt St Helens

Convergent Collision

Mountain Range Himalayas

Intra plate Volcanoes• Hot Spots created by mantle plumes

Hawaiian Volcanoes

Hawaiian VolcanoesHawaiian Volcanoes

Yellowstone is a Continental Hotspot

The driving force of Plate Tectonics is mantle convection

Historical Evidence for Plate Tectonics

Development of the Plate Tectonic Theory• Combination of two pre-existing ideas

– Continental Drift• Idea that continents move freely over the Earth's surface, changing

their position relative to one another

– Sea-floor spreading• Hypothesis that the sea floor forms at the crest of the mid-oceanic

ridge then moves horizontally away from the ridge crest toward an oceanic trench

The Theory of Plate TectonicsContinental Drift

5.Sea Floor Spreading

The Theory of Plate TectonicsContinental Drift

5.Sea Floor Spreading

Geology of the Ocean Floors

Continental Drift

Skepticism about Continental Drift

• Wegner imagined that the plates plowed through the ocean floor, this would crumple mountain ranges on the edges of continents.

• His rate of motion was too fast• There was no mechanism to support

Continental Drift• http://

videos.howstuffworks.com/science-channel/29267-100-greatest-discoveries-continental-drift-video.htm

• http://science.discovery.com/tv-shows/greatest-discoveries/videos/100-greatest-discoveries-continental-drift.htm

Alfred Wegener

Continental Drift

• First Indication was the similarity of the coastline between South America and Africa

• Early 1900s Alfred Wegner found further evidence

1. Geographic Fit of the Continents

Laurasia

GondwanaPangea

Pangaea Continent Location

Pangea

Pangea Breakuphttp://www.classzone.com/books/earth_science/terc/content/visualizations/es0806/es0806page01.cfm?chapter_no=visualization

2. Paleontological Evidence (Fossil Distribution)• Plant and Animal fossils that are found in Africa, S.

America, Antarctica, India and Asia (Gondwana)

– Glossopteris

– Lystrosaurus

– Mesosaurus

– Cynognathus

3. Evidence from Structure and Rock Type

The Appalachian Mountains continues into Europe where they are known as the Caledonian Mountains

4.Evidence from Glaciation

5. Paleoclimactic Records from the Jurassic

Coal Deposits on Antarctica

Evidence for Continental Drift

1. Geographic fit of the Continents2. Fossils found in Brazil and Africa3. Rock Types and Structural Fit of the

Continents4. Patterns of Glaciation5. Paleoclimactic Records

Sea Floor Spreading

6. The Topography and Geology of the Ocean Floor• Mid Ocean Ridge

• Oceanic Crust is thinner than continental crust• Crust has not been subjected to compressional forces and is not

deformed• Oldest sediment on the ocean floor is 200 my old and far away from

spreading center

Age of Ocean Sediments increase away from the mid ocean ridge

7. Rock Magnetism• Iron rich rock (Basalt) has been weakly

magnetized by the Earth’s magnetic field and

become fossil magnets

8. Evidence from earthquakes• Earthquakes highlight plate boundaries• 1 Year of Earthquakes

Rates of motion• Plates move at different rates

– San Andreas= 5.5cm/yr

– Himalayas=5.54cm/yr

– Mid-Atlantic Ridge= 3cm/yr

– Andes=10.1cm/yr

Key Concepts: lines of evidence for Plate Tectonics

• For many years, the leading Earth scientists believed that Earth’s continents and oceans formed in their current positions. The scientists also proposed that land bridges once connected the continents. They used the idea of land bridges to explain why similar plants and animals may be found on widely separated continents.

• In 1912, German meteorologist Alfred Wegener raised a challenge to the idea of static, non-moving continents. Wegener’s proposal was that continents moved across the ocean, an idea he called continental drift.

• According to Wegener, the continents had been joined together millions of years ago. He called the supercontinent Pangaea, meaning “all the land.” Over time, Pangaea broke apart, and the continents drifted to their present locations.

• To support his ideas, Wegener cited the following evidence:– Some pairs of continents, especially South America and Africa, appear to have matching coastlines.– Fossils of the same species had been discovered on opposite sides of the oceans. These species included freshwater fish and land plants

that could not have easily crossed the ocean.– Some mountain ranges on opposite sides of oceans have matching rock layers.– After Wegener had died, scientists found new evidence that supported his ideas. Much of this evidence was discovered in the 1940s and

1950s from studies of the ocean floor. The scientists discovered huge underwater chains of mountains called mid-ocean ridges. The mid-ocean ridges spread across the centers of all oceans. The ridges are parallel to the continents’ coastlines.

– Other evidence from the ocean floor includes matching layers of rocks on either side of the mid-ocean ridge. The magnetic orientation of iron in the rocks acts as a kind of time marker. It provided evidence for an idea called seafloor spreading. According to this idea, the ocean floor forms at the mid-ocean ridge, then spreads apart from the ridge over time.

• Most Earth scientists of Wegener’s time dismissed the idea of continental drift. They asked Wegener how continents were able to move. Wegener could not answer this question.Today, scientists use the theory of plate tectonics to explain the features of Earth’s surface. The theory incorporates many of Wegener’s proposals, including the idea of moving continents that once formed Pangaea. However, plate tectonic theory proposes that all the lithosphere, not just the land, is divided into large, moving sections. Each plate contains land, ocean, or a combination of land and ocean.

Plate Tectonics Vocabulary

plate tectonics: the scientific theory that Earth’s crust is made of large plates that slowly move

fold: a ripple in Earth’s crust

magma: melted rock in Earth’s mantle

fault: a break or crack in a tectonic plate

earthquake: a sudden release of pressure in Earth’s crust that causes shaking on the surface

seafloor spreading: the formation of new crust as two oceanic plates move apart

mid-ocean ridge: a chain of underwater mountains where seafloor spreading occurs

rift valley: a valley formed when continental plates move apartAlfred Wegener: German meteorologist who proposed the idea of continental drift

Pangaea: a large supercontinent that existed millions of years ago

continental drift: Wegener’s proposal that continents move across Earth’s surface

theory of plate tectonics: the scientific theory that the lithosphere is divided into large moving sections called tectonic plates

mid-ocean ridge: a chain of underwater mountains formed where two tectonic plates move apart

seafloor spreading: the process by which the ocean floor forms at the mid-ocean ridge

Key Concepts: Crustal Features of Plate Tectonics• 3 Types of Plate Boundaries• According to plate tectonics, Earth’s crust is made of large moving plates. The place where two plates meet is a plate boundary.

At plate boundaries, plates can push together, move apart, or slip past each another.

• Folded mountains form when rock layers are squeezed together and pushed upward to create folds, or ripples, in the crust. Folded mountains form where tectonic plates collide, crumple, and thicken at a continental-continental plate boundary.

• Continental plates collide with oceanic plates at continental-oceanic boundaries. The oceanic plate slides under the continental plate. Volcanic mountains can form along the boundary.

• Two plates may also collide at oceanic-oceanic plate boundaries. One oceanic plate is pushed under the other, and a deep trench forms.

• Evidence of Plate Tectonics• When magma erupts on the ocean floor, it forms a chain of volcanic mountains. If the mountains become high enough, they

form islands.• Another mountain-building process causes fault-block mountains to form. Tension and pressure can build up along a fault. The

land sometimes shifts to release the pressure. Large blocks of rock on one side of a fault can be pushed up or down.

• An earthquake occurs when rock in Earth’s crust slips and quickly releases pressure. Earthquakes are common near plate boundaries and faults.

• When two oceanic plates move apart, magma from the mantle flows up into the space between the plates. The magma hardens to form new crust. This process is called seafloor spreading.

Long chains of volcanic mountains form along a boundary where oceanic plates pull apart. These long chains of underwater mountains are called mid-ocean ridges.

• New crust can also form at the boundary of two continental plates. On land, rift valleys form when continental plates move apart.

Plate Tectonics Vocabularytheory of plate tectonics: the scientific theory that the Earth’s crust is divided into large moving sections called tectonic platesTectonic Plate: the lithosphere of the earth is divided into a small number of plates which float on and travel independently over the mantle and much of the earth's seismic activity occurs at the boundaries of these plate Lithosphere: The rigid outer layer of the earth that is broken into tectonic plates. The lithosphere is the crust and upper mantle.Asthenosphere: The partially molten layer beneath the lithosphere. This is the lubricating layer that the tectonic plates slide on.Subduction Zone: The area where one tectonic plate slides beneath another plate.Oceanic Trench: a long narrow valley on the ocean floor that runs parallel to a volcanic range. It is the surficial expression of a subduction zone. rift valley: a valley formed when continental plates move apartmid-ocean ridge: a chain of underwater mountains formed where two tectonic plates move apartFault: a fracture in the Earth’s crust where rocks on the opposite sides have been displaced from one another.earthquake: a sudden release of pressure in Earth’s crust that causes shaking on the surfaceVolcano: a vent in the Earth’s crust through which lava is expelledAlfred Wegener: German meteorologist who proposed the idea of continental driftcontinental drift: Wegener’s proposal that continents move across Earth’s surfaceseafloor spreading: the process by which the ocean floor forms at the mid-ocean ridgePangaea: a large supercontinent that existed millions of years ago

TEKS• (8.9) Earth and space. The student knows that natural events can

impact Earth systems. The student is expected to • (A) describe the historical development of evidence that supports

plate tectonic theory; Supporting Standard • (B) relate plate tectonics to the formation of crustal features; and

Readiness Standard • (C) interpret topographic maps and satellite views to identify land

and erosional features and predict how these features may be reshaped by weathering. Readiness Standard

• (7.8) Earth and space. The student knows that natural events and human activity can impact Earth systems. The student is expected to

• (C) model the effects of human activity on groundwater and surface water in a watershed. Supporting Standard

Key Concept Graphics