FORCES OF CHANGE

By Jack Garrity

Book pages 34-40

Internal Forces of Change The center of the Earth is filled with intense

heat an pressure. These natural forces drive numerous change such as volcanoes and earthquakes that renew and enrich Earth’s surface.

Earth’s Structure The Earth’s internal and external structure

including the tectonic plates, is responsible for the creation of the continents, oceans, and mountain ranges.

Wind and water make slow changes to the land all the time.

A Layered Planet The Earth has three main layers- the core, the

mantle, and the crust.

A Layered Planet The inner core is made up of iron and nickel

7,200 to 9,000 degrees.

A Layered Planet The much bigger outer core is made of melted

iron and nickel ( 10,800 F).  .

A Layered Planet The mantel is a 1,800- 6,300 degree layer of

silicon, aluminum, iron and other elements.

A Layered Planet Parts of the mantel get hot and rise towards

the crust, then cool and sink towards the outer core.

A Layered Planet The Biosphere is on the crust, the rocky cool

part of the Earth.

A Layered Planet The Crust is thin 2-75 miles thick.

A Layered Planet The Biosphere is on the crust, the rocky cool

part of the Earth.

A Layered Planet The Crust is broken into more than 16 rocky

pieces that float on the mantle called plates.

Plate Movement These 12 or more plates carry the continents

and oceans on them.

Plate Movement 500 Million years ago the continents were part of a super continent called Pangaea.

Plate Movement Pangaea broke apart according to the theory

of continental drift.

Plate Movement Plate tectonics is the study of how and why

these plates move and the geography they make.

Plate Movement Plates move slow, usually only an inch or two

a year.

Plate Movement Scientists think the heat rising from the core

create currents in the mantel that move plates.

Internal Forces of Change Plate tectonics is responsible for folding,

lifting, bending, and breaking parts of the Earth’s surface.

Colliding and Spreading Plates Mountains are made when continental plates

collide.

Colliding

Colliding and Spreading Plates The collision between the India and Asian plates

made the Himalaya Mountains, which are still getting higher.

Colliding and Spreading Plates These

Colliding and Spreading Plates The collision of a Sea Plate and Continental

Plate makes volcanic mountains.

Colliding and Spreading Plates The heavy Sea Plate goes under the

Continental Plate called subduction.

Colliding and Spreading Plates Slower collisions cause accretion, which

cause continents to grow.

Accretion : the process of growth or increase, typically by the gradual accumulation of additional layers or matter.

Colliding and Spreading Plates Island chains can be made when one plate

moves under the other.

Colliding and Spreading Plates Plates that move apart is called spreading,

which makes volcanic mountains.

Colliding and Spreading Plates An underwater volcanic mountain range runs

down the middle of the Atlantic Ocean.

Colliding and Spreading Plates North America and Europe are moving away

from each other due to spreading.

Iceland is on the Mid Atlantic Ridge

Folds and Faults Plates sometimes squeeze the surface until it

buckles.

Folds and Faults Making folds in layers of rock, folded

mountains.

Folds and Faults Sometimes plates move past each other,

making faults.

Folds and Faults Faults are made when the crust cannot bend

anymore.

Folds and Faults Tension builds up and is released in a tremor.

Earthquakes Earthquakes are caused by sudden movement

of plates along a fault line.

Earthquakes

Earthquakes Ea

Earthquakes The Ring of Fire around the Pacific Plate has

the most earthquakes.

Volcanic Eruptions The Ring of Fire also has the most volcanoes.

Volcanic Eruptions Volcanoes are mountains made by magma or

lava.

Volcanic Eruptions One plate going under another plate into the

hot mantle can build up pressure.

Volcanic Eruptions Ash and gas can explode making a funnel.

Volcanic Eruptions Magma rises to the surface.

Volcanic Eruptions Lava can form a large volcanic cone toped by

a bowl shaped top.

Volcanic Eruptions Parts of Japan and South America are built on

the Ring of Fire.

Volcanic Eruptions Other volcanoes are made by extra hot spots

in the mantel.

Volcanic Eruptions These hot spots melt the surface as plates

move over them.

Volcanic Eruptions Hawaii’s islands were made this way.

Volcanic Eruptions These hot spots can also heat ground water,

like Old Faithful in Yellowstone National Park.

Volcanic Eruptions Large volcanic eruptions cause changes in weather

and temperatures , and can destroy civilization.

External Forces of Change

External Forces of Change

Book pages 39-40

External Forces of Change External forces such as weathering and

erosion also shape the surface of the Earth.

Forces such as wind and water also change the Earth’s surface. Wind and water movements involve two processes. Weathering breaks down rocks, and erosion wears away the Earth’s surface.

External Forces of ChangeWe will look at 5 forces that change the earth

surface: weathering, wind erosion, glacial erosion, water erosion, and soil building.

WeatheringWeathering breaks down rocks with rain

and wind in two ways.

WeatheringPhysical weathering breaks down big rocks

into smaller ones.

WeatheringRain water that runs into cracks of stones

can freeze.

WeatheringWhen water freezes it gets bigger and the

rock splits.

WeatheringIt can take hundreds of years, yet the results can go quickly.

WeatheringChemical weathering changes the rock into

something different.

WeatheringRainwater that has carbon dioxide can melt

rocks like limestone.

WeatheringMany famous caves are made this way.

Fchangevideo\Amazing Crystal Cave - How Earth Made Us - S1 Ep1 Preview - BBC Two.mp4

Wind ErosionThe wind can change the Earth’s surface.

Wind ErosionThe wind can blow good soil away, making

deserts out of once good farmland.

Wind ErosionThe wind can blow good soil away, making

deserts out of once good farmland.

http://s.hswstatic.com/gif/dust-bowl-cause-1.jpg

Wind ErosionThe wind can blow good soil away, making

deserts out of once good farmland.

http://s.hswstatic.com/gif/dust-bowl-cause-1.jpg

Wind ErosionThe wind can also drop good farming soil

onto areas.

Glacial ErosionGlaciers are large bodies of ice that move

across the ground.

Glacial ErosionHeavy snow presses together to form ice on

the bottom.

Glacial ErosionWith more snow, the ice begins to move

slowly downhill, or spread out.

Glacial ErosionGlaciers can flatten mountains.

Glacial ErosionThey pick up rocks and soil.

Glacial ErosionThey can destroy forests

Glacial ErosionChange the course of rivers

Glacial ErosionCarve out valleys.

Glacial ErosionAs they melt, they sometimes leave a huge

pile of rocks and soil called a moraine.

Glacial ErosionSome moraines make a dam, creating a

glacial lake.

Glacial ErosionTwo types of glaciers sheet and mountain

glaciers.

Glacial ErosionSheet glaciers cover most al Greenland and

all of Antarctica.

Glacial ErosionSheet glaciers get larger in the winter, and

smaller in the summer.

Glacial ErosionSheet glaciers get larger in the winter, and

smaller in the summer.

Glacial ErosionSometimes large pieces of Sheet Glaciers

fall off into the ocean making an iceberg.

Glacial ErosionMountain Glaciers are found in high

mountain valleys.

Glacial ErosionMountain Glaciers carve out round U

shaped valleys as they move downhill.

Glacial ErosionThey drop rock and soil moraines as they

melt (recede) in the summertime.

Water ErosionWater running down hill cuts into rock and soil

(dirt).

Water ErosionOver long periods of time, this can make a

gully then a valley.

Water ErosionThe Grand Canyon the most spectacular

example.

Fchangevideo\National Geographic - Amazing Flight Over The Grand Canyon.mp4

Water ErosionOceans waves erode cliffs and beaches

along the coast.

Water ErosionWaves turn rocks into smaller rocks, smaller

rocks into sand.

Water ErosionWaves turn rocks into smaller rocks, smaller

rocks into sand.

Water ErosionWaves turn rocks into smaller rocks, smaller

rocks into sand.

Water ErosionWaves turn rocks into smaller rocks, smaller

rocks into sand.

Water ErosionWind, waves and ocean currents can then

move sand other parts of the coast.

Soil BuildingSoil takes thousands of years to make.

Soil BuildingSoil is made by weathering and living

things.

Soil BuildingWeathering and erosion breaks down rocks

into sand or small particles.

Soil BuildingLiving things, like worms, break down dead

plants and animals.

Soil BuildingA mixture of the two groups makes soil.

Soil BuildingSoil can be good for farming and growing

things.

Soil BuildingMost importantly, growing things depends on the

temperature and amount of water the soil gets.

Water CycleThe amount of water on the Earth remains the same.

It moves from place to place in the water cycle.

Water Cycle97 percent of the worlds water is in the Oceans. 3

percent fresh water is essential for life.

Water CycleWe drink ground water, part of the 3

percent, without it we could not live.

END