Changes to earth’s Surface

1. Changes to earth’s Surface

2. Earth’s layers • Crust: (0-100 km thick) • Thinnest layer • Mantle: (2900 km thick) • Upper layer is made up of the lithosphere (solid) • It is also made up of the asthenosphere (taffy-like) • Lower layers are iron and magnesium silicate. • Core • Outer Core (2200 km thick): made out of very hot liquid iron and nickel. Produces Earth’s magnetic field. • Inner Core (1250 km thick): very hot, but is a solid ball

3. Wind, water, & gravity • Wind and water cause weathering on Earth’s surface. • Erosion moves weathered items to new locations. • Usually by gravity • Depends on several factors: • Hardness of item • Strength of force • It is called sediment. • Sediment gets carried by water or wind and is deposited in new locations. • These new locations are usually close by, but sometimes they are far away.

4. Ice changes earth’s surface • 2 types of glaciers • Alpine glaciers: found on mountain ranges; form in valleys and travel slowly downhill • Continental glaciers: very massive; cover all of Antarctica • Glaciers carry rock, debris, and sediment as they flow. • They smooth out the landscape . • When it melts it leaves behind large amounts of sediments. • It also pushes down the ground, which creates valleys when they melt or retreat.

5. Impacts change earth’s surface • Meteorites enter Earth’s atmosphere and forms a crater when it hits the surface. • Some craters are small, but a few have caused some major damage. • Small craters: • Brent in Ontario 3.8km • Odessa in Texas 0.168km • Large Craters: • Chicxulub in Mexico 170km • Sudbury in Ontario 250km

6. Earth’s Plates • Earth is made up of jigsaw pieces-or plates • The plates vary in size and shape • They are mostly named by the oceans and continents they carry • Ie…Pacific Plate, South American Plate • They are constantly moving: a few centimeters a year. • They move because of ‘plasticity’: • they can flow because the asthenosphere is like taffy

7. Plate Boundaries • 3 types of plate boundaries • Divergent boundaries • Convergent boundaries • Transform fault boundaries • Divergent Boundary • 2 or more plates are moving away from each other • As the plates separate, hot rock from the mantle rises up • This hot rock cools and then hardens into new crust

8. Plate boundaries cont. • Convergent Boundary • 2 plates push into each other • Continental Plate + Continental Plate= mountain ranges • the collision between the Eurasian Plate and the Indian Plate that is forming the Himalayas. • Continental Plate + Oceanic Plate= mountains or volcanoes • Cascade mountain range, extending north from California's Sierra Nevada • Oceanic Plate + Oceanic Plate= arc of volcanic islands • Japan and the Aleutian Islands in Alaska

9. PLATE BOUNDARIES CONT. • Transform Fault Boundary • Crust is not formed or destroyed • Plates grind, or rub past each other as they move in opposite directions • This causes earthquakes • Example is the San Andreas fault in California http://www.learner.org/interactives/dynamicearth/plate.html

10. PLATE movements • Long ago, a supercontinent existed • It is called Pangea • Scientists studied rock types, fossils, the magnetic field of rocks to discover Pangea • Today, the Atlantic Ocean is growing and the Pacific Ocean is shrinking and Africa is getting closer to Europe. • Earth will look different in about 200 million years from now.

11. Earthquakes • Pressure placed on rocks causes them to bend and break • This break is called a fault. • Faults form along plate boundaries or within a plate • When rocks snap and slide an earthquake occurs • Focus: the point inside Earth where an earthquake begins • Epicenter: the point directly above the focus

12. Earthquakes cont. • 3 types of seismic waves: • Primary waves (P waves) • Fastest wave 2.Compress and expand 3. Travel through the interior • Secondary waves (S wave) • Second-fastest wave 2. Travel through the interior 3. Move at 90* angles: side to side or up and down • Surface Waves • Travel along Earth’s surface 2. Shake the ground side to side or roll across the land 3. Causes the most damage!!!

13. Measuring Earthquakes • A seismograph measures and records earthquake waves • Magnitude is the size of an earthquake wave • 3 types of scales to measure magnitude • Richter Scale: • Estimates the amount of energy released • 0.0 – 10.0 • Moment Magnitude Scale • Measures the distance a rock moved along the fault

14. Measuring Earthquakes cont. • Mercalli Intensity Scale: • Measures the damage an earthquake causes • Uses Roman numerals: I -XII • Earthquakes can cause damage away from the epicenter • Earthquakes in the ocean can cause a tsunami • Tsunami: • A large wave that slams into the coast • Can be as tall as 30m or 100ft • Can cause extreme damage to buildings and shores

15. volcanoes • Located along the boundaries of Earth’s plates • 3 types of volcanoes: • Shield • Cinder Cone • Composite • The type of volcano depends on the type of eruption • Explosive eruption: materials thrown violently out of the vent • Nonexplosive eruption: lava flows slowly

16. Volcanoes cont. • Shield Volcano: • Broad, slightly domed shaped • May erupt several times over 1 million years • Is formed by nonexplosive eruptions • Erupts quietly • Cinder Cone Volcano • Have steep sides • Erupt for a short period of time/no taller than 300m • Erupts violently: ash and rock are thrown out

17. Volcanoes cont. • Composite Volcano • May erupt on and off for 1 million years • Can erupt violently or gently • Similar shape to the cinder cone