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Ch. 16. Plate Tectonics. Layers of the Earth. Thickness: 5 – 40 km Composition: Oxygen, Silicon, Aluminum, Calcium, Iron, Sodium, Potassium, Magnesium Temperature: Up to 1,600 degrees F. Crust. Thickness: 2,900 km - PowerPoint PPT Presentation
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PLATE TECTONICS
Ch. 16
LAYERS OF THE EARTH
CRUST Thickness: 5 – 40 km
Composition: Oxygen, Silicon, Aluminum,
Calcium, Iron, Sodium, Potassium, Magnesium
Temperature: Up to 1,600 degrees F
MANTLE Thickness: 2,900 km
Composition: Silicon, Oxygen, Iron, Magnesium
Temperature: 1,600 F to 8,000 F
The uppermost part of the mantle is the lithosphere.
Lithos means “stone”.
The soft layer of the mantle, beneath the lithosphere, is the asthenosphere. Asthenes means “weak”.
OUTER CORE Thickness: 2,250 km
Composition: Iron, Nickel
Temperature: 2,200 F to 11,000 F
INNER CORE Thickness: 1,200 km
Composition: Iron, Nickel
Temperature: 9,032 F to 13,000 F
LAYERS OF THE EARTH
Skin of the peach is the crust
Meat of the peach is the mantle
Pit of the peach is the core
TYPES OF ROCKS Igneous
Sedimentary Metamorphic
IGNEOUS ROCKS Formed from
molten material including volcanic lava, ash, or bombs as well as magma below Earth’s surface.
TYPES OF IGNEOUS ROCKS
GRANITE BASALT
SEDIMENTARY ROCKS Made of layers
that have been pressed or cemented together
Pebbles, sand, silt, or clay are sediments
Shells and bones can also be sediments
TYPES OF SEDIMENTARY ROCKS
SHALE LIMESTONE
COAL
METAMORPHIC ROCKS Rocks that are
changed by intense heat and pressure while inside Earth’s surface
Igneous, sedimentary, and even metamorphic rocks can be changed into different metamorphic rocks.
TYPES OF METAMORPHIC ROCKS
SLATE MARBLE
ROCK CYCLE
The rock cycle is a never-ending process of rocks forming, weathering, and changing into other rocks
ROCK CYCLE
FAULTS OCCUR BECAUSE FORCES INSIDE EARTH CAUSE EARTH’S PLATES TO MOVE, PLACING STRESS ON OR NEAR THE PLATE EDGE.
WHEN ROCKS BREAK, THEY MOVE ALONG FAULTS.
Applied forces cause rocks to undergo elastic deformation.
When elastic limits are passed, rocks break.
•Rocks on one side of a fault can move up, down, or sideways in relation to the rocks around them.
Rocks will bend, compress, stretch, and possibly break.
EARTHQUAKE - VIBRATIONS PRODUCED BY BREAKING ROCK. Rocks break, move along the fault, return to original shapes.
Rock on one side of a fault can move over, under, or past each other along fault lines.
SEISMIC WAVES
Are waves generated by an earthquake; can move the ground forward, backward, up & down, side to side.
Focus - an earthquake’s point of energy release.
A seismic wave’s speed and direction change as the wave moves through different layers with changes in densities.
SEISMOGRAPH - MEASURES SEISMIC WAVES.
Consists of a rotating drum of paper + a pendulum with an attached pen.
Makes a paper record of a seismic event called a seismogram.
Shadow zones do not receive seismic waves because the waves are bent or stopped by materials of different density.
Density Generally increases with depth as pressure increases.
CHANGES IN SEISMIC WAVE SPEED ALLOWED DETECTION OF BOUNDARIES BETWEEN EARTH’S LAYERS.
ALTHOUGH EARTHQUAKES ARE NATURAL EVENTS, THEY KILL MANY PEOPLE AND CAUSE A LOT OF DAMAGE.
Seismologists are scientists who study earthquakes.
•Most earthquakes are of a magnitude too low to be felt by humans - 3.0 to 4.9 on the scale.
DIVERGENT PLATE BOUNDARY
A place where two plates move apart, or diverge
Most occur along the mid-ocean ridge where sea-floor spreading occurs.
MID-OCEAN RIDGE
Mountains that lie mostly hidden under the ocean
Iceland is a part of the mid-ocean ridge that rises above the surface.
MID-OCEAN RIDGE
SEA FLOOR SPREADING
The sea floor spreads apart along both sides of a mid-ocean ridge as new crust is added.
As a result, the ocean floors move like conveyor belts, carrying the continents along with them.
SEA FLOOR SPREADING
RIFT VALLEY
Forms along the divergent boundary, only it forms on land
RIFT VALLEY
CONVERGENT PLATE BOUNDARY
The place where two plates come together, or converge
When two plates collide, the density of the plates determines which one comes out on top.
TRANSFORM BOUNDARY
A place where two plates slip past each other, moving in opposite directions
Earthquakes often occur along these boundaries.
TRANSFORM BOUNDARY
SUBDUCTION
A process in which the ocean floor sinks beneath a deep-ocean trench and back into the mantle.
SUBDUCTION