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Physical Processes that Shape the Earth (World Geography)
Transcript of Physical Processes that Shape the Earth (World Geography)
Physical Processes that Shape the Earth
Layers of the Earth
There are four layers that make up the earth's interior parts and exterior appearance.
The Convection Current and Continental Drift Theory
Convection Current: This is what drives tectonic plates. Magma from the mantle is heated by pressure, causing it to become less dense and rise. Cooler magma sinks, and then the process restarts. This cycle moves the mantle and the layers above it.
Tectonic Plates Theory
Tectonic Plates: The theory is that the lithosphere is broken into plates that slowly move over the asthenosphere, the top layer of the mantle. Each plate boundary interacts with one another, forming certain oceanic and land features.
Convergent Boundaries = Plates that Collide
Oceanic and Oceanic: As the two plates move apart, magma rises to fill the crack in between. Mid-ocean ridges form in these situations. Ex. Atlantic Ridge
Transform Boundaries = Plates that Slide and Grind
by Alliana D. (2nd Period)
The earth we live in today does not look the same as it was millions of years ago. Continents and oceans are constantly changing, whether it is unnoticed and slow or sudden and distributed throughout the news worldwide. The natural processes do not occur out of context, however. Everything has a start.
Inner Core: The very center of the earth. It is made of iron and nickel under intense heat and pressure. It is pure solid.
Outer Core: The layer that surrounds the inner core. This layer is in the liquid state and is also made of the same elements as the Inner Core.
Mantle: The thick layer filled with hot dense rock. The mantle has lots of activity inside it such as the Convection Currents.
The small layer part of the crust (lithosphere) is where tectonic plates are at.
This is what scientists believe to be what the inside of the earth looks like. The numbers are estimations of how long each layer might be.
Crust: The thin layer that is visible to us. This is where all life roams.
The asthenosphere, the small layer right above the mantle, slowly moves due to the convection current, carrying the lithosphere and the crust.
Continental Drift: The theory that all continents were once connected but have drifted apart. The drifting was because of the movement made by Convection Currents.
Hotter magma rises, cooler magma sinks.
This diagram shows how Convection Currents work.
The mass continent is called Pangaea. It slowly broke off over the years and continents drifted apart because of the tectonic plates moved by convection currents.
Continental Drift Theory
There are three main types of plate boundaries.
Convergent Boundaries: Plates that collide with each other.
Divergent Boundaries: Plates that move away from each other.
Transform Boundaries: Plates that slide past or grind against one another.
Ring of Fire: The ring of fire is located on the Pacific Plate. This is an area of numerous volcanoes and earthquakes from the Pacific Plate's interactions with other plates around it.
This image shows which plate is located at with their names. The Ring of Fire is located at...
The boundaries of each plate is where most activity occurs.
the Pacific Plate.
Continental vs. Oceanic Plates: The more dense plate (oceanic) is subducted, pushed by gravity, under the continental plate. The subduction zone forms an ocean trench. Ex. Mariana Trench
The melted rock subducted rises up the land and forms volcanic mountains. Ex. Andes Mts.
Continental vs. Continental: Since they have equal density, when the two plates collide, they rise up and form folded mountain ranges, such as the Himalayas between India and China.
Oceanic vs. Oceanic: The more dense oceanic plate subducts under the other. This causes island arcs from underwater volcanoes.
Subduction zones are where land is pushed into the mantle. Land goes down, magma is pushed up.
Divergent Boundaries = Plates that Drift Away
Continental and Continental: As the land separates, the height of the ground lowers, which conjures rift valleys. Eventually, water will fill the space between the two plates. Ex. Great Rift Valley in Africa
These plates slowly move past one another, but due to the friction in between them, pressure is slowly built up. Once the pressure breaks, a fault is formed and the strong force causes earthquakes.
If an earthquake occurs in the ocean, a tsunami can possibly happen.
Weathering and Erosion
Weathering: The breaking down of rocks on the earth's surface.
Erosion: The wearing away of earth's surface because of wind, moving water, and glaciers.
At the subduction zone, a trench is formed while the melted rock rises to the continental crust and creates volcanic mountains.
Result: Andes Mountains
If two continental crusts collide, the outcome is the form of mountain ranges as both plate boundaries rise up.
Result: the Himalayas between India and China
As two plates divide, they form a ridge in between through the process of seafloor spreading, where magma rises up to fill the crack.
Result: Mid-Atlantic Ridge
In other cases, when two plates aren't too spread apart, they will only form a rift valley, where the ground slopes down until eventually, the area will fill with water.
Result: Great Rift Valley in Africa
Due to the force of transform boundaries, some massive earthquakes can damage certain things in the land such as buildings, trees, roads, etc.
If an earthquake occurs in the sea, the force can create a super wave that will possibly reach land. The massive waves are called tsunamis, and they will obliterate anything that is in their path.
As a result of the sliding movement, a fault or a crack will form in between the two plate boundaries.
Result: San Andreas Fault in California
This song explains weathering and erosion on a deeper depth.
An example of weathering is that water can get into small cracks or holes inside rocks. They may stay inside and possibly freeze, but once the water is warmed again, the rocks break due to the water expanding the occupied area.
Water can carry away loose sediments and deposit them somewhere else. The Grand Canyon was created over the years by water erosion.
Weathering and Erosion Song by Mr. Parr
Wind in deserts carry away the sand and form sand dunes (left). Deflation hollows (right) are created when the sand is eroded by the wind over multiple years.
Glacier erosion is when a glacier moves over the land, scraping the dirt and other minerals away, carrying it to a new location and leaving the area bare.
Educational Purposes Only
Sources for Information:
Google Images tool used in the Prezi editing area
notes used in class lessons
notes used from past years
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