Unit 1: The World Chapter 2: The Physical World

Our Solar System Sun and the objects that revolve around it Center is sun (ball of burning gases) Enormous mass creates pull of gravity The planets- Largest objects. 8 Mercury, Venus, Earth, Mars are inner planets Jupiter, Saturn, Uranus, and Neptune are the outer planets Jupiter is the largest. Earth is 5th. All have moons except Mercury and Venus. Earth has 1 and Saturn as 18 Terrestrial solid, rocky crusts. Mercury, Venus, Earth, Mars Gas Giants- gaseous and dense. Jupiter, Saturn, Uranus, Neptune. Miniature solar system

Our Solar System Asteroids, Comets, Meteoroids Thousands revolve around sun Asteroids are small, irregularly shaped. Asteroid belt found between Mars and Jupiter Comets- icy dust particles and frozen gases. Meteoroids- space debris- chunks of rock and iron. Usually burn up before they reach Earth. 1908 Serbia

The Planets

Getting to Know Earth * Diameter at Equator is 7,930 miles. Larger than from pole to pole by less than 1% Circumference of 24,900 miles. Largest of inner planets Landforms 7 continents- N and S America, Europe, Asia, Africa, Australia, Antarctica Isthmus of Panama connects Americas. Sinai Peninsula connects Asia and Africa Continental Shelf- extension of coastal plain underwater. Slope out from land about 800 miles descend to 600 ft. slope starts there. Then ocean floor.

Getting to Know Earth 70% water. Hydrosphere * Water, Land and Air 70% water. Hydrosphere 30% land. Lithosphere. Earth’s Crust Air is part of atmosphere. 70% nitrogen. 21% oxygen Biosphere- plants, animals, people Mt. Everest- 29,028ft. Above sea level Dead Sea- 1,349ft. Below sea level Mariana Trench- 35,827ft below sea level The sun is in the center of all orbits There are smaller planets closer to the sun There is a mix of planet sizes further away

Earth’s Surface Always in motion Layered Planet- Mantle, crust, core Center of Earth is hot solid core. Iron and nickel. Surrounding inner core band of melted iron and nickel called liquid outer core. Mantle- thick layer of hot, dense rock. Silicon, aluminum, magnesium, and oxygen. Rises, cools, sinks, warms up, ect. 80% of heat generated here. Crust- rocky shell. 2 miles to 75 miles thick. Broken into plates. Float on partially melted layer in upper portion of mantle. Carry oceans and continents.

Earth’s Surface Plate Movement Pangaea- original landmass. Continental drift- theory of how continents were joined, drifted apart and recombined. Plate tectonics- physical ways landmasses were created. Mountains, oceans etc. gradual. 1 inch a year. Push up mountains, create volcanoes, produce earthquakes Plates spread apart and magma (molten rock) rises up and ridges formed. Plates bump together, sliding under each other forming a trench

Internal Forces of Change Colliding and Spreading Plates Mountains formed when plates collide. Himalayas thrust upward when Indian landmass drifted against Eurasia. Subduction- heavier sea plate dives beneath the lighter continental plate. Sea plate becomes molten. Magma bursts through to form volcanic mountains. Andes. Accretion- crust comes together as sea plates slide under continental plates. Make continents grow Island chains formed from one plate moving under another. Spreading allows for magma to rise to the surface creating undersea mountains and ridges. Folds and Faults Folds, or bends, happen when plates squeeze the surface until it buckles. Faults are created when two plates rub together. San Andres fault in CA Faulting occurs when folds cannot bend anymore and the earth breaks into huge blocks. Releases a series of small jumps felt on the surface.

Internal Forces of Change Volcanic Eruptions Along plate boundaries. Mountains formed by lava or magma. Rock plate melts as it goes down into the mantle. If rock is too thick the flow is blocked and pressure builds. Cloud of ash and gas rise up creating funnel with magma. Lava forms the cone shaped top and crater. Away from plate boundaries. Earth’s center is so hot that pressure blasts through the surface as volcanoes. Create island chains. Heat underground water and make geysers

Internal Forces of Change Earthquakes Violent movements of tectonic plates along fault lines. 1964 earthquake in Alaska raised the ground 38 ft. Occur where plates meet. Tension builds up as plates stick. Ground splits and snaps under pressure. Shock waves go out as pressure is released. Ring of Fire- most earthquake prone areas in world. Kobe, Japan, Las Angeles, and San Francisco on this line. Zone of volcanic and earthquake activity along the perimeter of the Pacific Ocean.

External Forces of Change Weathering Weather breaks down the rocks. Physical- large masses of rocks are broken down into smaller pieces Chemical- changes in the actual make up of the rock. Rainwater with carbon dioxide. Wind Erosion Movement of soil, dust, and sand from one location to another. Plants and trees help to stop this Dust carries mineral rich soil to new areas.

External Forces of Change Glacial Erosion Huge pieces of ice that move. Displace rocks and soil. Carve out valleys, destroy forests, divert rivers Moraines- large piles or rock and debris. Can form dams and create lakes. Sheet glaciers- broad, flat sheets. Greenland and Antarctica. Become icebergs. Grow in winter and recede in summer Water Erosion Spring water and rainwater cut into the rocks and soil. Forms a gully then a valley. Sometimes form canyons. Oceans help this. Waves erode coastal rocks, soils, and beaches.

Water Cycle Most of Earth covered in water. Salt water is the majority. Total amount of water does not change but the water does change location. Water cycle keeps water level constant. From oceans, to air to land and finally back to oceans. Major force behind the cycle is the sun which evaporates the water. Amount of vapor held by air depends on temperature. Warm, dense air holds more vapor than cold air. Warm air cools condensation appears. Forms clouds and they form precipitation. Amount of water that evaporates is about the same amount that falls back to Earth.

Bodies of Salt Water 70% of Earth’s surface is water Oceans 97% of Earth’s water is in oceans. One continuous body of water. 5 oceans Pacific, Atlantic, Indian, Arctic, and Southern Pacific is largest and covers more area than all of the land. Deep enough in some places to cover Mt. Everest with 1 mile to spare Seas, gulfs, and bays are smaller. Salt Water to Fresh Water Most water is not drinkable. Desalination is one way to fix this.

Bodies of Fresh Water About 3% of total water is drinkable. 2% is unattainable because it is frozen in glaciers. 0.5% is beneath surface. Lakes, streams, and rivers make up less than 1% of freshwater. Lakes, Streams and Rivers Completely surrounded by land. Most contain freshwater. Exceptions are Asia’s Dead Sea and Utah’s Great Salt Lake Most lakes are glacial. Streams start from lakes, melting water or spring. Flows to larger river. Flows hundreds of miles to empties into larger body of water. Groundwater Comes from melted snow and rain Wells and springs tap into this source of water. Rural areas. Aquifer is an underground porous rock layer that is saturated by slow flows of water.