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

Divergent Volcano

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

World Earthquake Map

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 Secondary (S) 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