Forces that Change the Earth
Forces that Change Earth!
Forces that Change Earth!
Forces that Change Earth!
Forces that Change Earth!
Forces that Change Earth!
Forces that Change Earth!
Forces that Change Earth!
YOU LOSE
REPLAY???
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 changesare 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 reallyhard 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 andproteins 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 theplanet requires an understanding of the insides of theplanet.
Earth’s LayersThe 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 Plates8 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
http://members.enchantedlearning.com/subjects/astronomy/planets/earth/Continents.shtml
Alfred Wegener 1900’sContinents 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
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 pushedfarther away from the ridge
How Plates Move
http://pubs.usgs.gov/gip/dynamic/unanswered.html
Different Types of Boundaries
http://pubs.usgs.gov/gip/dynamic/understanding.html
Plate MovementsPlates can move in three ways.
Apart
Together
Past each other
Fred can you demonstrate for us?
Not that kind of plate Fred!
Plates Moving ApartWhat 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.
FaultsThe 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.