Chapter 2 Planet Earth

Chapter 2:1 Objectives Planet Earth 1. Describe the solar system and Earth’s location in it. 2. Identify the earth’s shape. 3. Discuss Earth’s structure. 4. List Earth’s landforms.

Terms to Know (p ) Hydrosphere Lithosphere Atmosphere Biosphere Continental shelf

Drawing from Experience Have you ever seen a picture of Earth from space? What features do you see? When you look from Earth to space, what features do you see? This section focuses on what humans know about the physical nature of our planet Earth.

Water, Land & Air Water, land and air make up the physical environment of the earth.

Our Solar System Our solar system is made up of the sun and all of the objects that revolve around it. The sun is the center of our universe and is a ball of burning gases. The huge amount of matter (mass) in the sun creates a strong pull of gravity.

This physical force keeps the earth and the other objects revolving around the sun. Planets are the largest objects in the solar system, besides the sun. Each planet moves in its own orbit around the sun.

The Milky Way

There are 9 known planets in our solar system.

Mercury – a hot, inner planet, is closest to the sun.

Venus is a hot, inner planet. Venus and Mercury do not have moons.

Earth is an inner planet, 3 rd from the sun, 5 th in size and the only planet that has liquid water and supports life.

Mars is a cold, barren desert. It is an inner planet.

Jupiter is an outer planet and the largest of all.

Saturn is an outer planet with at least 18 moons. Can you spot Earth?

Uranus is an outer planet.

Neptune is an outer planet and a gas (methane) giant.

Pluto is an outer planet, the smallest and a ball of ice & rock.

Terrestrial Planets Have solid, rocky crusts. They are… Mercury Venus Earth Mars

Gas Giant Planets Are larger, more gaseous, and less dense than terrestrial planets. They are… Jupiter Saturn Uranus Neptune

Other Objects Besides planets, other objects that revolve around the sun include asteroids, comets, and meteoroids.

Asteroids are small, oddly shaped, planet-like objects.

Comets are made up of icy, dusty particles and frozen gases.

When Comets Collide

Meteorites – large pieces of rock and iron.

Impact! Winslow, Arizona

Question What occurs when a meteorite slams into the earth? 3 minute video over meteor strike Should schools develop an emergency plan for meteor strikes?

Getting to Know Earth The earth’s surface is made up of water and land. About 70% of the earth’s surface is water. The earth’s hydrosphere consists of bodies of water such as oceans, lakes and rivers.

About 30% of the earth’s surface is land, or lithosphere. Earth’s atmosphere is a layer of gases that extends about 6000 miles above the surface. The biosphere is the part of earth where people, plants and animals live.

Landforms The natural features of the earth’s surface are called landforms. Earth is made up of 4 major types of landforms: Mountains Hills Plateaus Plains.

Mountains

Hills

Plateaus

Plains

Landforms are found on the earth’s surface and underwater. The largest landforms on Earth are the seven continents. The continental shelf is the part of the continent that extends underwater.

Continental Shelf

Continents in order of Size 1. Asia 2. Africa 3. North America 4. South America 5. Antarctica 6. Europe 7. Australia AANSAEA

Surface Differences The earth has great differences in the heights and depths of its surface. Mount Everest is its highest point at 29,037 feet above sea level. The shore of the Dead Sea is the earth’s lowest point at 1349 feet below sea level.

Mt. Everest

Dead Sea -- Israel

Question What types of landforms are found of Earth? Answer: mountains, hills, plateaus and plains

Chapter 2:2 Objectives Forces of Change 1. Explain how Earth’s layers contribute to the planet’s physical characteristics. 2. Describe the internal forces of change that affect Earth’s surface. 3. Describe the external forces that affect Earth’s surface.

Terms to Know mantle continental drift magma plate tectonics subduction accretion spreading fold fault weathering erosion loess glacier moraine

Chapter 2, Sec. 2 Building Geography Literacy: In 1906 the booming city of San Francisco was destroyed by an earthquake that measured 8.6 on the Richter scale. Over 400 people were killed, and 28,000 buildings were reduced to rubble. Another slightly less forceful earthquake struck the city in 1989, doing far less damage and claiming 67 lives. Most people remember it because it interrupted the World Series for 12 days while damages were repaired in Oakland and San Francisco.

Drawing from Experience Have you ever felt the earth move under your feet? Have you ever experienced a dust storm? Have you ever watched a quick moving stream? In section 1 we talked about the features of the earth. This section focuses on the forces that change the surface of the earth.

What is the Interior of the Earth Like? Scientists have evidence that the center of the earth is active with intense heat and pressure. Movements within the earth cause changes to the earth’s surface.

Earth’s Structure The earth is made up of three layers. A. The core is the center of the earth. The inner core is solid, very hot and under intense pressure. It contains iron and nickel. The outer core is liquid. It is made up of melted iron and nickel.

B. The mantle is a thick layer of hot, solid rock. It is made up of many elements. C. The crust is a rocky shell that forms the earth’s surface. The crust is broken into several huge slabs of rock called plates.

Continental Drift Many scientists believe in continental drift. This is a theory that the continents were once joined and then slowly drifted apart. Many scientist also believe that the moving plates created the earth’s largest features – oceans, continents and mountains.

Pangea

Plate movement is constant and very slow. As the plates move, they crash into each other, spread apart, or grind and slide past each other. The movement of plates are called plate tectonics. When the plates spread apart, magma, or melted rock, pushes up from the mantle.

What has created the earth’s largest features? Plate tectonics!

Discussion Question Why might a scientist want to study plate tectonics? Answer: If people knew more about why the plates move, when they are likely to move, and in which direction, they might be able to prepare for disasters like earthquakes or volcanic eruptions.

Internal Forces of Change There are six (6) internal forces of change. (Mt. Vesuvius) Do you know where this is? What city did it destroy?

1. Subduction Mountains can form when continental plates collide. For example: the Himalaya Mountains can also be formed by subduction – where a sea plate slides underneath a continental plate. The sea plate melts as it crashes into the mantle, and The resulting magma bursts through the crust to form volcanic mountains.

subduction

In another process called accretion, pieces of the earth’s crust pile up slowly as a sea plate slides under the continental plate. This accumulating debris causes continents to rise.

2. Spreading Spreading is a process in which sea plates pull apart. This causes deep cracks in the ocean floor, Releasing magma which hardens into undersea volcanic mountains or ridges.

3. Folds Moving plates sometimes squeeze the earth’s surface, causing folds or bends in layers of rock.

fold

4. Faults Grinding or sliding plates create cracks in the earth’s crust called faults.

San Andres Fault

5. Earthquakes Earthquakes are caused by sudden, violent movements in plates along a fault line.

Alaskan Earthquake

West Yellowstone, MT – 7.5

6. Volcanic Eruptions Volcanic eruptions can occur when one plate plunges beneath another. Magma often blasts through the surface of the earth as volcanoes. Volcanic island chains can form from the molten rock.

Mount St. Helens -- Washington

Reventador in Equador

Question What are the 6 internal forces that cause the surface of the earth to change?

External Force of Change Wind and water change the earth’s surface.

A. Weathering Weathering is the process that breaks down rocks on the earth’s surface into smaller pieces.

B. Erosion is the wearing away of the earth’s surface by wind, glaciers and moving water. It can cause the loss of soil and lead to dust storms. Wind erosion can also create deposits of mineral-rich soil called loess, a fertile, yellow-gray soil found in China.

Glaciers are large bodies of ice that slowly move across the earth’s surface, causing erosion. As glaciers move, they pick up rocks and soil and carve grooves in the landscape. When glaciers melt and withdraw, they leave behind large piles of rock and debris called moraines.

Mendenhall Glacier (Alaska)

Water erosion is mostly caused by fast- moving water in streams and rivers that wears away soil and rock. The pounding waves of oceans cause erosion along coasts.

Water Erosion – Lower Falls of the Yellowstone River

Wind Erosion – Arches N.P.

Question What are two external forces that cause changes to the earth’s surface? Answer: wind and water

Discussion Question Explain why water may be more powerful than rock. Answer: Water can wear away or dissolve rock over time. Although rocks can displace water, they cannot wear it away or destroy it.

Chapter 2:3 Objectives Earth’s Water 1. Explain how the amount of water on Earth remains fairly constant. 2. Discuss the distribution of water that makes up 70% of Earth’s surface. 3. Describe why freshwater is important to humans.

Terms to Know water cycle evaporation condensation precipitation desalination groundwater aquifer

Building Geography Literacy The Caspian Sea in southeastern Europe/southwestern Asia is actually a salt lake – the largest one on Earth. It is a lake, not a sea, because it is surrounded by land. The ancient Romans called the Caspian a sea because its water was salty. Australia’s Lake Eyre, Venezuela’s Lake Maracaibo, and Utah’s Great Salt Lake are other notable saltwater lakes.

Drawing from Experience When you turn on a water faucet, do you ever wonder where the water comes from? What is the source of the water you use to drink, cook and bathe? In the last section you learned about the forces that change the earth’s surface. This section focuses on the earth’s water.

All living things need water to survive. Water on Earth comes in three forms: A. The liquid form of water is in rivers, lakes and oceans. B. The gas form of water is held in the atmosphere. It is sometimes called water vapor. C. The frozen form of water is in glaciers and ice sheets.

Where is the Earth’s water found? In liquid form – rivers, lakes, oceans. Gas form in the atmosphere – water vapor. Frozen form – glaciers & ice sheets.

The Water Cycle Almost all of the hydrosphere is salt water found in oceans, seas and saltwater lakes. The rest is freshwater found in lakes, rivers and springs.

Mediterranean Sea

Caribbean Sea

Yangtze River in China

Lake Yellowstone

The total amount of water on Earth does not change! The water cycle is the constant movement of water from the oceans to the air to the ground and finally back to the oceans.

The Water Cycle has 4 main stages: A. Evaporation: is the changing of liquid water into vapor (gas). The sun’s heat causes water vapor to rise from the oceans and other bodies of water into the atmosphere.

B. Condensation: is the stage in which warm air cools and some of the water vapor changes back into liquid water. Tiny droplets of water come together to form clouds. C. Precipitation: rain, snow, sleet, falls from clouds that contain more water than they can hold.

D. Surface runoff is formed from the precipitation as it falls to the ground. This water collects in rivers, lakes and oceans.

Question? What are the four main stages of the water cycle?

Discussion Question What will eventually happen to the water you ran in the sink this morning while brushing your teeth? Answer: Since the total amount of water remains the relatively constant, it will eventually return as precipitation to its source.

Bodies of Salt Water About 70% of the earth’s surface is water. Almost all of the earth’s water is salt water. There are four main kinds of bodies of salt water… oceans, seas, gulfs, bays.

Oceans make up about 97% of the earth’s water. There are four oceans…can you name them? Pacific Atlantic Indian Arctic.

The Pacific is the largest and covers more area than all the earth’s land combined. Seas, gulfs and bays are much smaller than oceans. These bodies of water are partially enclosed by land.

The water found in oceans is too salty for drinking, farming or manufacturing. A process is being developed, called desalination, for obtaining freshwater from oceans by removing the salt content. Where is most salt water on Earth found?

Bodies of Freshwater (pg. 48) About 3% of Earth’s total water supply is freshwater. Most of this 3% is not available to use. More than 2% of Earth’s total water supply is frozen in glaciers and ice caps. About 0.5% is found beneath the earth’s surface (ground water).

Lakes, streams and rivers contain less that 1% of the earth’s water. This water is important to people because it meets their everyday needs. For this reason, most large urban areas began as settlements along the shores of lakes and rivers where people could have a constant supply of water.

Another source of freshwater is groundwater, which lies beneath the earth’s surface and supplies wells and springs. Groundwater comes from rain and melted snow that filter through the soil. It also comes from water seeping into the ground from lakes and rivers.

In areas with little water, people sometimes depend on aquifers for their water supply. An aquifer is an underground porous rock layer often filled with water in the form of streams.

Texas Panhandle

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