The Earth

Chapter 2, Section 1

Section Objectives

• Analyze how processes deep within the Earth affect its surface

• Identify major landforms and analyze how they affect life on Earth

• Identify the causes of earthquakes and volcanoes

• Understand the importance of water and the hydrologic cycle.

Inside the Earth• Earth has three layers:

- Crust- 31 to 62 miles deep

- Thickest under continents; thinner below the oceans

- Mantle- Layer of rock 1,800 miles thick!

- Outer mantle = sometimes melts, creating magma, or melted rock

- Inner mantle = solid

- Outer Core- Mostly liquid; molten iron and nickel

- 1,400 miles thick

- Inner Core- Solid iron due to pressure from above!

- 700 miles thick; reaches 12,000°F

Tectonic Plates

• Earth’s crust is divided into sections called tectonic plates:– The earth’s crust consist of

plates, or huge slabs of rock, that move

– Plates float on top of liquid rock just below the crust

– Plates often move in different directions

– Oceans and continents sit on top of these gigantic plates!

Iceland, where the North American plate meets the European plate

Plate Tectonics Map

Pangea• Scientists believe

that long ago all the continents were joined together in a land mass called Pangea

• However, eventually, the continents drifted apart - this is called “continental drift”– Bill Nye: Pangea & Plate Tectonics (Cut at 2:00)

Pangea, cont.• The plates are still moving today

– Plate under the Pacific moves west at 4”/year– Plate along west edge of S. America moves east at

1.8”/year

• Some scientists believe that in another 250 million years, the continents will be rejoined!

When Plates Meet• Sometimes plates push against each

other, leading to one of four things– Plates smashing into each other =

mountain ranges, like the Himalayas

– Thicker continent plate sliding over a thinner ocean plate = volcanic mountains, which erupt when pressure between plates builds up

– Plates sliding alongside each other = earthquakes along faults, or cracks in the earth’s crust

– Plate movement along faults, like the San Andreas Fault in California, can produce damaging earthquakes and tsunamis, or underwater earthquakes.

The Ring of Fire

• The Ring of Fire is a circle of volcanoes and earthquakes along the rim, or outer edge of the Pacific Ocean.

• A large tectonic plate under the ocean slides against plates in the surrounding continents.

Today’s Questions:How does the movement of tectonic plates impact landforms on earth?

What landforms are created?

How does this impact us,the people who live on oraround these landforms?

Earthquakes & Tsunamis– An earthquake is a violent shaking of the Earth’s crust– Occur along faults, or cracks in the earth’s crust

– Happens often in the Ring of Fire, but also in other areas,

– Earthquakes beneath the ocean can produce tsunamis, or large, powerful ocean waves which can cause great destruction along the ocean coast.

– Earthquake Destruction (2:21)

– Killer Tsunamis (3:28) 2011 Japanese Tsunami Footage (5:39)

Earthquake Damage! Tsunami - November 2006!

Earthquake!San Andreas Fault, CA, USA

China, 2008 - 8.0 Richter

Italy, 2009 - 6.3 Richter

Pakistan, 2005 - 7.6 Richter

Volcanoes• A volcano is a mountain that erupts in an

explosion of molten rock, gases, and ash.– Lava, which is molten rock, flows down the sides of

the mountain.– The Ring of Fire contains more than 75% of the

world’s volcanoes.– In spite of their destructive tendencies, volcanoes

can benefit, or be useful to, plants and animals by making the soil richer

Volcano 101 (3:04)Yellowstone Volcano (1:36)

Landforms are physical features on the Earth’s surface.

They are continually reshaped by physical processes

Landforms

Surface Landforms Mountain – a high,

steep elevation Hill – slopes upward,

but is lower and more rounded

Plain – a level area Plateau – a plain that

sits high above sea level and usually has a cliff on all sides

Ocean Landforms

Mountains, valleys, and volcanoes also exist at the bottom of the ocean.

Continental shelf – the edge of a continent that extends several miles under the ocean’s surface At the edge of the shelf, the land slopes

steeply to the ocean floor

Diving along the Eurasian Continental Shelf!

Ocean Landforms, cont.

Valleys under the ocean are called trenches Lowest spots in the

earth’s crust Mariana Trench =

deepest trench in the world, located in the west Pacific

Dive the Mariana Trench! (:47)

Ocean Landforms, cont.

Computer imaging of Puerto Rico Trench, Atlantic Ocean

Deep Sea - Exploring the Zones (5:54)

The Changing Earth• Changes in the earth

affect plant and animal life

• Erosion: the process by which rocks and soil slowly break apart and are swept away

• Weathering: when air, water, wind, or ice slowly wear away rocks and soil– Bill Nye: Erosion (Cut at 6:48ish)

Erosion and Weather at Work

Waters of the Earth

Water flowing in rivers is essential – or necessary – for all forms of life!

About 70% of the earth is water!

Most of it is salt water, which people can’t drink

Fresh Water People use fresh

water to drink, cook, and irrigate crops River – a path of

water that flows from a higher elevation to a lower elevation

Streams, brooks, and creeks – like rivers, only smaller

Lake – a large body of water surrounded by land

Salt Water Salt water is a major

source of seafood and a means of transportation

Oceans – large bodies of Salt Water Currents – continuously

moving flows of water – circulate through oceans affect the climates on land

Seas – Smaller bodies of salt water

Ex. Red Sea

The Water Cycle• Evaporation – The sun heats the ocean and water vapor

rises up into the atmosphere

• Condensation – Cooler temperatures in the atmosphere cause the water vapor to change into droplets that form clouds

• Precipitation -- Water droplets grow heavier and fall back to Earth in the form of precipitation, which is rain or snow

• Runoff (or Collection) – Precipitation soaks into the ground and runs into rivers , underground water reservoirs, and eventually, the ocean

Percentage of Water on Earth:– 96.5% Oceans– 1.7% Ground Water– 1.8% Surface Water– .024% Other Water – (Ground ice, atmospheric water vapor, marshes/wetlands,

and in lorganisms

–Of the amount of water on earth, only 2.5% is available for human use!

• Water Cycle Rap• Thirstin's Water Cycle• Soccer Game• Stuck In Your Head Song

Landforms: An Amazing Variety!

Escarpment

DEFINITION: A long, steep, cliff-like ridge of land or rock, commonly formed by faulting or fracturing of the earth's crust

TerraceDEFINITION: A leveled section of a hilly cultivated area, designed to slow or prevent rapid run-off of irrigation water

Valley

DEFINITION: The low area between mountains or hills

Gully

DEFINITION: Similar to a valley, only smaller

Archipelago

DEFINITION: A large group or chain of islands

Coral Reef

DEFINITION: a reef or underwater ridge composed mainly of coral and other organic matter which has hardened into limestone.

Cove

DEFINITION: A round indentation or recess with a narrow entrance, located in the shoreline of a sea, lake, or river.

Headland

DEFINITION: An area of land with water on three sides (large headlands are called peninsulas).

LagoonDEFINITION: An area of salt water separated from a larger sea by a sandbank or coral reef

Cave

DEFINITION: A natural underground opening in a cliff or rock, big enough for a person to enter.

Gorge & Canyon

Above: Royal Gorge, CO

Right: Grand Canyon

DEFINITION: A deep valley with steep sides, formed by streams carving through plateaus. (A gorge is a small canyon!)

Waterfall

DEFINITION: A flow of water that drops over rocks, usually from a height of several feet.

SpringBig Spring, Ozarks, MO (Largest spring in the U.S.!

Right: Grand Prismatic Spring, Yellowstone

(160 degrees F!)

DEFINITION: A place where groundwater flows out of the ground.

Crevasse

Gorner Glacier, Zermatt, Switzerland

Easton Glacier, Mount Baker, WA

Exploring bottom of crevasse in Antarctica

DEFINITION: A crack in a glacier or snow field.

FjordAbove: Fjords on coast of Greenland (Bottom is largest fjord in the world!)

DEFINITION: A valley with steep sides, which is below sea level and filled with salt water.

MountainDEFINITION: A natural elevation of the earth's surface rising to a summit, steeper and higher than a hill.

Cinder ConeDEFINITION: A small, cone-shaped volcano built of ash and cinders.

Oceanic Trench

DEFINITION: A long narrow steep-sided depression in the earth's crust under the ocean.

Lava DomeDEFINITION: A mound-shaped growth resulting from the eruption of lava in a volcano

Tea Table

DEFINITION: A rock formation that has been eroded away in the shape of a table

Limestone Pavement

DEFINITION: Exposed limestone rock that looks like artificial pavement with cracks in it.

Hoodoo

DEFINITION: A tall, thin spire of rock that sticks up from the bottom of an dry drainage basin or badland.

Any questions?