Earth Science Main Layers of the Earth: - PowerPoint Presentation

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Earth Science

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Main Layers of the Earth:

Crust

Mantle

Core

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The Crust

Hard , solid, and strongCooler than other layers

Thinner beneath the oceans and made of basalt

Thicker beneath the continents and made of granite

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The Mantle

Composed of two layers: the upper mantle and lower mantleUpper mantle is solid

Lower mantle is viscous

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The Core

Composed of iron and nickelMade of two layers: inner core and outer core

Outer core is liquid

Inner core is solid due to pressure

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The Lithosphere

The uppermost part of the mantle and crust together for a rigid layer called the lithosphere.

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The Asthenopshere

The hotter, less rigid

, viscous

layer underneath the lithosphere is called the

asthenosphere.

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Continents Today

North AmericaSouth America

Asia

Europe

AfricaAntarcticaAustralia

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Continents Millions of Years Ago

Alfred Wegner suggested we once had a supercontinent or one huge continent called Pangaea.

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Alfred Wegener

Alfred Wegener was a German scientist who supported his belief in Pangaea with the following evidence:

same rocks

Same fossils

Same plantsContinents fit together like puzzle pieces

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Continental Drift

Alfred Wegener proposed the theory or idea of continental drift. This theory stated that there was once a supercontinent that broke apart or divided. However, he could not explain why.

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http://www.geo.cornell.edu/hawaii/220/PRI/continental_puzzle.html

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Laurasia and Gondwana

Alfred Wegener believed that Pangaea broke into two pieces: a northern continent called

Laurasia

and a southern continent called

Gondwana

.

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Laurasia and Gondwana

Split

Laurasia

:

North America

EuropeAsia

Gondwana

:

South America

Africa

Antarctica

Australia

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How Did Pangaea Break Apart?

The earth is broken into seven large pieces and many smaller pieces called plates.

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How Did Pangaea Break Apart?

Continents and oceans ride on plates and it is the plate that move across Earth’s viscous mantle.

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Ridges

There are long cracks in the ocean floor called ridges where magma from the mantle oozes up and spills onto the ocean floor.

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Sea Floor Spreading

Plates move away from the ridge as new ocean crust forms. This movement of just a few inches each year is called sea floor spreading.

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Trenches

A trench is formed when and ocean plate meets a continental plate and ocean plate moves beneath the lighter continental plate. As it moves downward or

subduction

occurs, a deep trench is formed.

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Plate Boundaries

There are three types of plate boundaries:

Divergent boundaries

Convergent boundariesTransform boundaries

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Divergent Boundaries

The place where two plates move apart or diverge is called a divergent boundary. Most occur along the mid ocean ridges where sea-floor spreading occurs. On land, they create rift valleys.

Great Rift Valley in East Africa.

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Convergent Boundaries

The place where two plates come together or converge is called a convergent boundary . There are three types:

Ocean and ocean

Continent and continent

Ocean and continent

Fuego and

Acatenango

, as seen from

the flanks of the

Volcan

de Agua, near Antigua Guatemala

Fuego and

Acatenango

, as seen from

the flanks of the

Volcan

de Agua, near Antigua Guatemala

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Ocean to Ocean Subduction

Where two plates carrying oceanic crust meet at a trench, the plate that is more dense sinks under the other plate

.

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Ocean to Continent Subduction

The more dense oceanic crust sinks beneath the less dense continental plate.

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Continent to Continent

When two plate carrying continental crust collide,

subduction

does not occur. Neither piece is dense enough to sink. Instead, the collision squeezes the crust into mighty mountain ranges.

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Transform Boundaries

A transform boundary is a place where two plates slip past each other, moving in opposite directions. Earthquakes often occur along transform boundaries.

San Andreas Fault in California

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Faults

Faults - breaks in Earth’s crust where rocks have slipped past each other -form along boundaries

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Types of Volcanoes

Cinder ConeShield

Stratovolcano

or Composite

http://www.scholastic.com/play/volcano.htm

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Cinder Cone Volcano

Cinder cone volcanoes are formed from cinder, rock, and ash that are deposited around the vent after violent explosions.

Paricutin in Mexico

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Shield Volcano

Shield volcanoes are formed when lava flows gently from the vent, spreads and build a broad gently sloping mountain.

Mauna Loa in Hawaii

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Stratovolcano or Composite Volcano

Stratovolcanoes

or composite volcanoes are steep sided, cone shaped mountains that rise over 10,000 feet. They are made from alternating layers of gently flowing lava, ash, and cinder.

Mt.

Fugi

in Japan

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Harmful Effects of Volcanoes

Hot lava

Ash

Poisonous gases

Mudflows (lahars)

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Classification of Volcanoes

Active

- erupt regularly

Dormant/Inactive

– have erupted in historical times but are currently not erupting

Extinct – have not erupted in historical times

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Earthquakes – vibrations produced by the breaking of rock; studied by scientists called seismologists

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Focus and Epicenter

Focus - the point beneath Earth's surface where rock breaks under stress and the plates shift and that is what causes the earthquake.

Epicenter-

the part of the earth's surface directly above the focus of an earthquake

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Classification of Earthquakes

Richter Scale

– a measure of the energy released during the earthquake; ranges from 1-10

Modified

Mercalli

Scale

– a measure of the amount of damage done by the earthquake; ranges from 1-12

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Primary Waves / “P” Waves

Secondary Waves/ “S” Waves

Pushing and pulling

Wiggling

Fastest

Slower than primary waves

Can move through solid, liquid, and gases

Can only move through solids

Seismic Body Waves

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Mountains

Four types of mountains:

Folded mountains

Dome mountains

Fault block mountainsVolcanic mountains

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Folded Mountains

Folded mountains form when two plates push against each other and fold upward.

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Dome Mountains

Dome mountains are formed when plates push against each other and bulge making a shape like an upside-down bowl.

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Fault Block Mountains

Fault block mountains form along cracks or fault sin plates.

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Volcanic Mountains

Volcanic mountains are mostly found under the oceans where magma from Earth’s mantle pushes plates apart although they can also be found on land.

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Ring of Fire

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How Much of Earth’s Water is in Usable Form?

97% of Earth’s Water is Salt Water

2% of Earth’s Water is Freshwater that is frozen in Ice Caps and Glaciers

1% of Earth’s Water is Freshwater in Usable Form

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Eras of EarthPaleozoic

MesozoicCenozoic

http://www.science4us.com/elementary-earthspace-science/earth/history-of-earth/

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The Water Cycle

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The Water Cycle

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The Water Cycle

Water moves in cycles

Yes, it does!

Water moves in cycles

Yes, it does!

It goes up as evaporation

It forms clouds as

condensation

It comes down as

precipitation

Yes, it does!

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Types of Water Pollution

Chemical Pollution

Thermal Pollution

Organic Pollution

Ecological Pollution

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Chemical Pollution

The introduction of toxic substances into an ecosystem such as acid rain or pesticides

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Thermal Pollution

Varying temperatures above or below the normal condition

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Organic Pollution

Oversupplying an ecosystem with nutrients such as fertilizer

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Ecological Pollution

Adding a substance that is not usually there

Increasing the amount of intensity of a naturally occurring substance

Altering the level or concentration of biological or physical components of an ecosystem