Earth’s MovementEarth’s Movement

Plate Tectonics and FaultsPlate Tectonics and Faults

PangaeaPangaeaApproximately 200 million years ago Approximately 200 million years ago

Earth's land was grouped together in Earth's land was grouped together in one large super-continent named one large super-continent named Pangaea. Pangaea.

http://pubs.usgs.gov/gip/dynamic/historical.html

Jurassic & Cretaceous PeriodsJurassic & Cretaceous Periods

Pangaea began to break apart during Pangaea began to break apart during the Jurassic Period. the Jurassic Period.

http://pubs.usgs.gov/gip/dynamic/historical.html

Present DayPresent Day

http://pubs.usgs.gov/gip/dynamic/historical.html

Notice the shape of South America Notice the shape of South America and Africa. Can you picture how and Africa. Can you picture how

these two land masses fit together these two land masses fit together like a puzzle?like a puzzle?

EvidenceEvidence

Scientists have found evidence that Scientists have found evidence that the continents are moving in fossils. the continents are moving in fossils. For example, fossils of tropical plants For example, fossils of tropical plants were found in Antarctica which led to were found in Antarctica which led to the conclusion that this frozen land the conclusion that this frozen land had previously been closer to the had previously been closer to the equator.equator.

Fossil EvidenceFossil Evidence

http://pubs.usgs.gov/gip/dynamic/continents.html

Plate TectonicsPlate Tectonics

Plate Tectonics is a theory that was Plate Tectonics is a theory that was developed in the 1960's. This theory developed in the 1960's. This theory states that Earth's top layer called states that Earth's top layer called the the crustcrust is divided into plates that is divided into plates that are moving at a speed of 1 to 10 cm are moving at a speed of 1 to 10 cm per year. per year.

Tectonic PlatesTectonic Plates

http://pubs.usgs.gov/gip/dynamic/slabs.html

Another Picture of the Another Picture of the Tectonic PlatesTectonic Plates

FaultFault

The breaks in the Earth’s crust where The breaks in the Earth’s crust where the plates meet (push together, pull the plates meet (push together, pull apart, and slide beside each other) apart, and slide beside each other) are called faults.are called faults.

Plate MovementPlate Movement

The plates move in three ways:The plates move in three ways:

Divergent Plate Movement ←  → Divergent Plate Movement ←  →

Convergent Plate Movement  →  ← Convergent Plate Movement  →  ←

Transform Plate Movement or Transform Plate Movement or Lateral Slipping Plate Movement ↓↑ Lateral Slipping Plate Movement ↓↑

Divergent Plate Movement ←  → Divergent Plate Movement ←  →

Convergent Plate Movement  →  ← Convergent Plate Movement  →  ←

Transform Plate Movement Transform Plate Movement or or

Lateral Slipping Plate Movement ↓↑Lateral Slipping Plate Movement ↓↑

Mid-Ocean RidgesMid-Ocean RidgesMid-Ocean Ridges are places where Mid-Ocean Ridges are places where

the Earth's tectonic plates are the Earth's tectonic plates are gradually moving apart. As the plates gradually moving apart. As the plates move apart, magma rises up to fill move apart, magma rises up to fill the gap. This can cause undersea the gap. This can cause undersea volcanic eruptions. volcanic eruptions.

This shallow magma provides a heat This shallow magma provides a heat source that creates many seafloor source that creates many seafloor hot springs along the ridges which hot springs along the ridges which transport heat and chemicals into the transport heat and chemicals into the ocean. ocean.

Mid-Ocean RidgeMid-Ocean Ridge

http://pubs.usgs.gov/gip/dynamic/baseball.html

ActivityActivity You will be given a piece of waxed You will be given a piece of waxed

paper. On the wax paper spread a paper. On the wax paper spread a spoonful of icing about a half of a spoonful of icing about a half of a centimeter thick. The icing centimeter thick. The icing represents the magma that is represents the magma that is under the Earth’s crust. Next you under the Earth’s crust. Next you will be given two squares of fruit will be given two squares of fruit rollups. Place the two squares of rollups. Place the two squares of fruit rollup onto the frosting right fruit rollup onto the frosting right next to each other. These next to each other. These represent oceanic plates. Press represent oceanic plates. Press down slowly on the fruit rollups down slowly on the fruit rollups because oceanic plates are dense because oceanic plates are dense and will sink a bit. Slowly push the and will sink a bit. Slowly push the “plates” apart about half a “plates” apart about half a centimeter. Notice how the frosting centimeter. Notice how the frosting is exposed and pushed up where is exposed and pushed up where the plates are separated. This is the plates are separated. This is how magma comes to the surface how magma comes to the surface where real plates are moving apart where real plates are moving apart at at divergent plate boundariesdivergent plate boundaries. .

Volcanic ActivityVolcanic Activity

The black The black dots dots represent represent volcanic volcanic activity. activity. Notice that Notice that most of most of these are these are along the along the edges of edges of the plates. the plates. These are These are called fault called fault lines.lines.

http://pubs.usgs.gov/gip/dynamic/zones.html

Earth Gains New CrustEarth Gains New Crust

On On divergent plate boundariesdivergent plate boundaries new new crust is being formed as magma crust is being formed as magma escapes from the Earth's core. In escapes from the Earth's core. In other locations under the ocean are other locations under the ocean are deep trenches. deep trenches.

Earth Loses Old CrustEarth Loses Old Crust

Scientist believe these deep trenches Scientist believe these deep trenches are where the old crust is being are where the old crust is being lowered back into the Earth’s core. lowered back into the Earth’s core.

This cycle is known as the Wilson This cycle is known as the Wilson Cycle, named after John Tuzo Wilson.Cycle, named after John Tuzo Wilson.

Wilson CycleWilson Cycle

The cycle, beginning with new crust The cycle, beginning with new crust being formed to the old crust being formed to the old crust returning to the Earth's core, takes returning to the Earth's core, takes approximately 100 million years.approximately 100 million years.

Continents do not fall back into the Continents do not fall back into the Earth's core, so land masses are Earth's core, so land masses are much older than the Earth’s crust much older than the Earth’s crust beneath the ocean. beneath the ocean.

Points to RememberPoints to Remember

When plates move apart, volcanoes When plates move apart, volcanoes may form. may form.

←  → ←  →

← ← DivergentDivergent →  → 2 Oceanic Plates2 Oceanic Plates Submarine mountain rangesSubmarine mountain ranges Volcanic activityVolcanic activity EarthquakesEarthquakes New seafloor New seafloor

2 Continental Plates2 Continental Plates Rift valleyRift valley Earthquake activityEarthquake activity Volcanic activity sometimes occursVolcanic activity sometimes occurs

Convergent Plate Movement  →  ←Convergent Plate Movement  →  ←

Convergent boundaries are where Convergent boundaries are where plates are moving toward each other.plates are moving toward each other.

The outcome of convergent plate The outcome of convergent plate movement varies depending on the movement varies depending on the types of plates that meet:types of plates that meet:– Oceanic–Oceanic Oceanic–Oceanic – Oceanic-Continental (Land)Oceanic-Continental (Land)– Continental-Continental or (Land-Land)Continental-Continental or (Land-Land)

VocabularyVocabulary

Lithosphere - outermost layer of the Lithosphere - outermost layer of the earth's crust & is broken up into large solid earth's crust & is broken up into large solid plates called tectonic plates - about 40 - plates called tectonic plates - about 40 - 250 miles deep 250 miles deep

Asthenosphere - part of the earth just Asthenosphere - part of the earth just below the lithosphere - not liquid but there below the lithosphere - not liquid but there is a small amount of melted rock there - is a small amount of melted rock there - 250 - 435 miles thick 250 - 435 miles thick

Subduction - the process that takes place Subduction - the process that takes place at convergent boundaries →  ← in which at convergent boundaries →  ← in which one tectonic plate moves under the other one tectonic plate moves under the other

Oceanic-Oceanic ConvergenceOceanic-Oceanic ConvergenceWhen two oceanic plates collide, one is When two oceanic plates collide, one is

pushed under the other and magma pushed under the other and magma from the mantle rises, forming from the mantle rises, forming volcanoes. volcanoes.

http://pubs.usgs.gov/gip/dynamic/understanding.html

Lava FlowLava Flow

In some cases the magma calmly In some cases the magma calmly erupts. The lava emerges and cools erupts. The lava emerges and cools forming new crust. forming new crust.

Violent EruptionViolent Eruption

In other cases the volcano erupts In other cases the volcano erupts violently sending dust and ash into violently sending dust and ash into the sky. the sky.

Calderas Calderas In other cases the area above the In other cases the area above the

volcano has cracks which release volcano has cracks which release gases usually during a volcanic gases usually during a volcanic eruption. As the gases release the eruption. As the gases release the emptied chamber can no longer emptied chamber can no longer support the weight of the earth support the weight of the earth above it. The earth falls into this void above it. The earth falls into this void leaving deep craters called calderas.leaving deep craters called calderas.

Crater LakeCrater LakeOne famous example of a caldera is North One famous example of a caldera is North

America’s Crater Lake located in Southern America’s Crater Lake located in Southern Oregon. Around 7,000 years ago a Oregon. Around 7,000 years ago a massive volcanic peak reaching 12,000 massive volcanic peak reaching 12,000 feet in elevation set in this location. A feet in elevation set in this location. A powerful eruption blasted the top 4,000 powerful eruption blasted the top 4,000 feet away, leaving a deep bowl shaped feet away, leaving a deep bowl shaped caldera. Since that caldera. Since that

time, a new dome time, a new dome has begun to form in has begun to form in the center of the center of

the caldera. the caldera.

The factor that determines the type of The factor that determines the type of eruption is the amount of silica that eruption is the amount of silica that is in the lava. Silica is a very common is in the lava. Silica is a very common mineral composed of silicon and mineral composed of silicon and oxygen (SiO2). Silicates makes up oxygen (SiO2). Silicates makes up about 95% of the Earth’s crust. about 95% of the Earth’s crust. Volcanoes rarely change the type of Volcanoes rarely change the type of eruption that occurs. eruption that occurs.

ActivityActivity Slide the two Slide the two pieces of fruit pieces of fruit rollups together. rollups together. Notice that one Notice that one piece slides under piece slides under the other. A hump the other. A hump forms where the forms where the two pieces hit. two pieces hit. Volcanic mountain Volcanic mountain building occurs building occurs when two oceanic when two oceanic plates meet. plates meet.

Oceanic-Continental ConvergenceOceanic-Continental Convergence

When an oceanic plate pushes against When an oceanic plate pushes against a continental plate, the oceanic plate a continental plate, the oceanic plate moves under the continental plate.moves under the continental plate.

http://pubs.usgs.gov/gip/dynamic/understanding.html

ActivityActivity Remove one of the fruit rollups Remove one of the fruit rollups

from the frosting. (You may from the frosting. (You may eat it.) Place one of the eat it.) Place one of the graham cracker halves graham cracker halves lightlylightly onto the frosting next to the onto the frosting next to the remaining fruit rollup piece. remaining fruit rollup piece. The graham cracker The graham cracker represents the continental represents the continental crust, which is thicker and less crust, which is thicker and less dense than oceanic crust (fruit dense than oceanic crust (fruit rollup). It floats high on the rollup). It floats high on the asthenosphereasthenosphere (upper mantle (upper mantle of the Earth) so don't push it of the Earth) so don't push it down. Gently push the down. Gently push the continent (graham cracker) continent (graham cracker) towards the ocean plate (fruit towards the ocean plate (fruit rollup) until the two overlap, rollup) until the two overlap, and the graham cracker is on and the graham cracker is on top. The oceanic plate is top. The oceanic plate is subductedsubducted below the below the continental one. continental one.

When an oceanic plate meets a When an oceanic plate meets a continental (land) plate usually an continental (land) plate usually an oceanic trench will develop on the oceanic trench will develop on the ocean side and a mountain range on ocean side and a mountain range on the continental side. the continental side.

Continental-Continental Continental-Continental ConvergenceConvergence

When two continental plates collide, When two continental plates collide, mountain ranges are created as the mountain ranges are created as the crust is pushed upwards. You can feel crust is pushed upwards. You can feel this movement through earthquakes.this movement through earthquakes.

http://pubs.usgs.gov/gip/dynamic/understanding.html

ActivityActivity Remove both the cracker Remove both the cracker

and fruit roll up from the and fruit roll up from the frosting asthenosphere. frosting asthenosphere. Place one edge of both Place one edge of both crackers into the glass of crackers into the glass of water for just a few water for just a few seconds. Place the seconds. Place the crackers onto the frosting crackers onto the frosting with wet edges next to with wet edges next to each other. Slowly push each other. Slowly push the graham crackers the graham crackers towards each other. towards each other. Notice how the wet edges Notice how the wet edges crumple. This is how crumple. This is how mountains are made at mountains are made at convergent plate convergent plate boundariesboundaries! When ! When continents move towards continents move towards each other there is each other there is nowhere for the rock to nowhere for the rock to go but up! go but up!

Point to RememberPoint to Remember

When two plates move towards each When two plates move towards each other mountains form. other mountains form.

→  ←→  ←

→ → Convergent Convergent ←←Oceanic and Continental PlatesOceanic and Continental Plates Earthquake activityEarthquake activity Sometimes ocean trenchSometimes ocean trench VolcanoesVolcanoes Destruction of oceanic lithosphereDestruction of oceanic lithosphere

2 Oceanic Plates2 Oceanic Plates EarthquakesEarthquakes Oceanic trenchOceanic trench Destruction of oceanic lithosphereDestruction of oceanic lithosphere

2 Continental Plates2 Continental Plates Folding and faultingFolding and faulting Mountain rangesMountain ranges Earthquake activityEarthquake activity Shortening of platesShortening of plates

Transform Plate Movement or Transform Plate Movement or Lateral Slipping Plate Movement Lateral Slipping Plate Movement

↓↑↓↑When two plates move sideways When two plates move sideways

against each other, there is a against each other, there is a tremendous amount of friction which tremendous amount of friction which makes the movement jerky. This is makes the movement jerky. This is known as an earthquake. known as an earthquake.

ActivityActivity

Pick the two crackers up off the Pick the two crackers up off the frosting and turn them around so that frosting and turn them around so that two dry edges are next to each other. two dry edges are next to each other.

Push one cracker past the other to Push one cracker past the other to simulate a transform plate boundary simulate a transform plate boundary like the San Andreas fault! like the San Andreas fault!

Point to RememberPoint to Remember

When two plates move past each other When two plates move past each other earthquakes are likely to happen. earthquakes are likely to happen.

↓ ↑↓ ↑

↓↓Transform BoundaryTransform Boundary↑↑ Recurring earthquake activityRecurring earthquake activity Volcanic activityVolcanic activity

ReviewReview

Divergent Plate Movement ←  → Divergent Plate Movement ←  →

Convergent Plate Movement  →  ← Convergent Plate Movement  →  ←

Transform Plate Movement or Lateral Transform Plate Movement or Lateral Slipping Plate Movement ↓↑ Slipping Plate Movement ↓↑

http://pubs.usgs.gov/gip/dynamic/Vigil.html

http://pubs.usgs.gov/gip/dynamic/world_map.html

Ring of FireRing of FireThe Ring of Fire is a chain of volcanoes and The Ring of Fire is a chain of volcanoes and

oceanic trenches. Seventy-five percent of oceanic trenches. Seventy-five percent of Earth’s volcanoes are in the Ring of Fire. Earth’s volcanoes are in the Ring of Fire.

http://pubs.usgs.gov/gip/dynamic/fire.html

http://pubs.usgs.gov/gip/dynamic/Farallon.html