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Changing Earth’s Surface. Weathering and Erosion. Changes to Earth’s Surface. Earth’s crust is constantly in a process of change Weathering Erosion Deposition. Weathering. The process by which rocks are broken down into small pieces called sediment Caused by Wind Water Glaciers
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Changing Earth’s Surface Weathering and Erosion
Changes to Earth’s Surface • Earth’s crust is constantly in a process of change • Weathering • Erosion • Deposition
Weathering • The process by which rocks are broken down into small pieces called sediment • Caused by • Wind • Water • Glaciers • Meteorites
Erosion • Occurs when weathered material is carried away by wind or water • Responsible for some of our most impressive natural monuments • Example—The Grand Canyon
Deposition • Occurs when sediment is dropped off at a new location • Wind or water slows down or comes to a stop • Example—River Delta
Changing Earth’s Surface Volcanoes
Plate Tectonics • Theory that the lithosphere is divided into plates that are always moving • Pangaea • Supercontinent that once existed over 350 million years ago • Evidence: Puzzle piece fit of the continents, fossil and soil matches on different continents • Responsible for the formation of volcanoes and earthquakes
Volcanoes • Form when magma rises to Earth’s surface • Pyroclastic Flow • Ashes, Gases, and Magma that ooze or explode from volcanoes • Can form at divergent boundaries or subduction zones
Divergent Volcanoes • Plates above the asthenosphere separate • Magma rises up • As lava cools, new crust is formed • May be oozing or explosive
Subduction Volcanoes • Formed when a denser ocean plate sinks under a lighter plate (either ocean or land) • Magma comes to the surface
Shield Volcano • Broad and flat volcano • Resemble a shield laying on its side • Built up slowly over thousands of years, most often in layers of hardened lava • Mostly ooze lava from vents • Example—Mauna Loa, Hawaii
Composite Volcano • Formed of alternating layers of ashes and hardened lava • May be dormant for many years before exploding rapidly or may ooze for thousands of years • Example—Crater Lake, OR
Cinder Cone • Formed from blobs of congealed lava in a simple cone shape • Capable of violent explosions • Bowl-shaped crater at the summit • Example—Paricutin, Mexico
Changing Earth’s Surface Earthquakes
Earthquakes • Energy released from the snap and slide of Earth’s crust at a fault line • Fault • 2 or more plates slide past one another • Focus • Point inside Earth where an Earthquake begins • Epicenter • Point on Earth’s surface where Earthquake waves begin
3 Types of Seismic Waves • Primary (P) Waves • Fastest and Smallest Waves • Secondary (S) Waves • Medium Waves • Surface (R) Waves • Slowest and Most Dangerous Waves
Earthquake Waves • Measured with a seismograph • Scaled using the Richter Scale • Scale of 1-10 • 1 = least amount of damage • 10 = greatest amount of damage