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 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