Forces that Change the Earth

Forces that Change Earth!

YOU LOSE REPLAY??? Oh. Fred’s daydreaming again after going brain-dead playing FINAL WARDEATH UNIVERSE DUEL OF CHAOSLORDS VII for 14 hours straight. Get a job, Fred.

#1 What Fred fails to realize is… …that the Earth does change, but just not in the way he’s imagining. Some changes are very obvious and happen suddenly and with great force: However, most of Earth’s changes are VERY slow. They’re so gradual that they’re really hard to notice unless it’s your job to watch for such things. Let’s see some ways in which Earth changes constantly, both slow and fast.

#2 A look inside… Why do these bananas look like this? It’s because of chemical changes in the sugars and proteins inside the banana. Much like your body, your outward appearance very much depends on your inner workings. The Earth is no different. To study the surface of the planet requires an understanding of the insides of the planet.

Earth’s Layers The Earth's rocky outer crust solidified billions of years ago, soon after the Earth formed. This crust is not a solid shell; it is broken up into huge, thick plates that drift atop the soft, underlying mantle.

The Crust  Outermost layer  5 – 100 km thick  Made of Oxygen, Silicon, Aluminum

The Lithosphere & Asthenosphere  Lithosphere is in the Crust & Mantle  Asthenosphere is in the Mantle  Lithosphere & Crust are rigid and solid  Asthenosphere is plastic like and moves (where the convection currents flow)

The Mantle  Layer of Earth between the crust and the core  Contains most of the Earth’s mass  Is the largest layer  Has more magnesium and less aluminum and silicon than the crust  Is denser than the crust

The Core  Below the mantle and to the center of the Earth  Believed to be mostly Iron, smaller amounts of Nickel, almost no Oxygen, Silicon, Aluminum, or Magnesium

Tectonic Plates 8 Major Plates out of 3000 Plates

Plate Tectonics  Greek – “tektonikos” of a builder  Pieces of the lithosphere that move around  Each plate has a name  Fit together like jigsaw puzzles  Float on top of mantle similar to ice cubes in a bowl of water

Continental Drift Alfred Wegener 1900’s Continents were once a single land mass that drifted apart. Fossils of the same plants and animals are found on different continents Called this supercontinent Pangea, Greek for “all Earth” 245 Million years ago Split again – Laurasia & Gondwana 180 million years ago

Evidence of Pangea

Sea Floor Spreading

 Mid Ocean Ridges – underwater mountain chains that run through the Earth’s Basins  Magma rises to the surface and solidifies and new crust forms  Older Crust is pushed farther away from the ridge

How Plates Move

Different Types of Boundaries

Plate Movements Plates can move in three ways. Apart Together Past each other

Fred can you demonstrate for us? Not that kind of plate Fred!

Plates Moving Apart What does that cause?

Write It! Divergent boundary – when plates move apart forming a rift valley or a ridge.

Good question Fred! It forms the ridges in the ocean like this one the Mid-Atlantic Ridge. The plates pull apart and new land is created as it bubbles up from the mantle creating a ridge.

Divergent Boundary – Arabian and African Plates

The Great Rift Valley As plates move apart they can also cause a valley like the Great Rift Valley in Africa.

Ok Fred how about plates moving together? Not quite Fred!

Plates pushing together what do they cause? When plates of the same density collide the buckle and form mountains. If one plate is less dense than another subduction occurs. One plate slides under the other and volcanoes or mountains are formed.

Write It! Divergent boundary – when plates move apart forming a rift valley or a ridge. Convergent boundary – when plates move together forming mountains or volcanoes.

Convergent Boundary – Indian and Eurasian Plates

One more chance Fred plates moving past each other. Fred that is just wrong!

Plates that Move past each other and what they cause. Where plates slide past each other transform boundaries occur. They create faults and when they move they cause a great deal of damage in the form of earthquakes.

Faults The fault you are most familiar with is the San Andreas Fault in California. There have been several earthquakes in California that have caused major damage.

Earthquake damage.

Write It! 1.Divergent boundary – when plates move apart forming a rift valley or a ridge. 2.Convergent boundary – when plates move together forming mountains or volcanoes. 3.Transform boundary – when plates move past each other causing earthquakes.

Well that is the end of this lesson time to check for understanding! When one plate pushes against another it causes uplift. This uplift will likely result in a A.Rift B.Mountain C.Ridge D.Valley

Well that is the end of this lesson time to check for understanding! What causes the earthquake activity in California? A.High Tides B.Low Tides C.Plate Movement D.Volcanic Activity

Well that is the end of this lesson time to check for understanding! What caused the damage seen in the picture? A.Soil Erosion B.Heavy Rains C.Horizontal Movement of the Earth’s crust D.Volcanic eruption

Well that is the end of this lesson time to check for understanding! Plates pushing together cause A.Earthquakes. B.Rift Valleys. C.Mountains. D.Rivers.