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Changing Earth


Ashley Packard

on 29 July 2018

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Transcript of Changing Earth

Changing Earth
Continent-Continent: Alps and Himalayas mountain ranges

Oceanic-Oceanic: Mariana Trench or Philippine islands, Aleutian islands (Alaska), or islands of Japan

Oceanic-Continental: Cascade Mtns. (includes Mt. St. Helens)
San Andreas Fault
(in California)
Plates Spread apart (move away from each other)
Ocean: Mid-Ocean Ridges (and Rift Valleys)

Land: Rift Valleys (and Volcanoes)
DIVERGENT BOUNDARY: Specific Names of Landforms
Ocean: Mid-Atlantic Ridge (down the middle of the Atlantic Ocean) (p. 23)

Land: Great Rift Valley in Africa (p. 27)
What happens to the crust?

New crust is formed (created).
Plate Motion:
Moving together (toward each other)
Continent-Continent: mountains (p. 31)

Oceanic-Oceanic: deep-ocean trenches, island arcs (p. 32 on left)

Oceanic-Continental: deep-ocean trenches, coastal mountains (p. 32 on right)
What happens to the crust?

Crust is folded (where plates collide) or is destroyed where plates subduct
Scraping past each other
Surface fault
What happens to the crust?

Crust is neither created nor destroyed
Click on the following link to watch the animation:
Click on the following link to watch the animation:
Continental Drift…An Idea Before Its Time
 Alfred Wegener’s continental drift hypothesis stated that the continents had once been joined to form a single supercontinent. Wegener proposed that the supercontinent, Pangaea, began to break apart 200 million years ago and form the present continents.

Sea Floor Spreading
In the 1940’s, scientists began to use sonar to map large areas of the ocean floor
sound waves are sent down from ships on the surface; these waves bounce off the ocean floor, and back to the receiver; the amount of time it takes for the sound waves to go and return allows us to calculate the distance to the ocean floor (mapping is done with computers)
series of ridges near the center of the Atlantic Ocean was discovered;
ridges extended the entire length (north to south) of the Atlantic Ocean
Ridges were also found in parts of the Indian and Pacific Ocean
Sea Floor Spreading: The Evidence…
1968, scientists used a research ship to drill cores of rock from the bottom of the ocean floor
the rock was dated by measuring traces of radioactive isotopes left in the rock when it was created; discovered the rock was the youngest at the mid-ocean rift and oldest at the shores of the continents
measured the direction of the magnetic field that existed when the rock hardened. discovered that the Earth’s magnetic field is constantly shifting, leaving alternating bands of rock with reversed magnetic polarity
Based on collected data, Atlantic Ocean spreads about 1.25 cm a year, on average—about the same rate that your fingernail grows
Continental Drift
Alfred Wegener proposed that the continents were once a single land mass that drifted apart.

Called this supercontinent Pangea, Greek for “all Earth”
Matching Mountain Ranges
Sea Floor Spreading: The How…
Convection current: Boiling-like current of magma in the mantle (the layer below the crust). This current causes the plates to gradually move.
Seafloor Spreading: Magma below earth’s crust rises to the ocean surface through cracks and causes the ocean floor to slowly widen (example: mid-Atlantic ridge)
The Theory of Continental Drift
Alfred Wegener, 1912
The break up
of Pangaea
What is Pangaea?
Pangaea was the supercontinent Wegner believed existed before the continents separated.
So what made Wegner think the continents were once connected?
Continental Drift: The Evidence…
shape of the continents suggests that they could fit together like puzzle pieces
same animal fossils are found on continents separated by oceans
matching rock types and structures, including mountain belts that end on one continent and continue on another across the ocean and specific kinds of rocks and ages of each rocks are found on opposite shores of the Atlantic Ocean along coastlines
fossils of tropical plants are found in polar areas, suggesting that the continents now in polar areas were once near the equator
glacial deposits (which only could be created in cold polar areas) are found in tropical areas, suggesting that some continents now in tropical areas were once near the poles.
Continental Drift
Fossil Evidence
Glacier Evidence
Wegener’s theory was rejected by scientists because he could not explain what force pushes or pulls continents.
Rejecting the Hypothesis
Checkpoint: What are three types of evidence Wegner used to support his theory of continental drift?
Matching Landforms
Matching Fossils
Matching shape of continents
Evidence of Different Climate
As the World Turns…
Changes in the Earth’s Crust…Plate Tectonics
Evidence for Continental drift
Fossils- the same fossils were found on continents separated by oceans
Climate- fossils and rock evidence shows that continents that are now cold were once in a warm climate
Geology- the rocks of separated continents are the same kind or structures match up
Continent shape
Sea Floor Spreading
More Evidence is Found
Click on each of the links to discover more about each of the earth's layers!
Using a small fish tank filled with water placed over a bowl of hot water and a bowl of ice, the convection currents can be seen using red and blue food dye.
Layers of the Earth
During the course of this prezi...
you will discover many things about our ever changing Earth...
Each concept will need to be completely understood and recorded on your Changing Earth foldable...
if there is something interesting you find...
Be sure to record it in one of the 10 available spots on the front of your foldable...
By the time you are finished...
You will have...
A better understanding of the planet you inhabit...
As well as a phenomenal tool to help you pass the quiz at the end of this lesson...
Please be sure to read and follow all directions...
Your journey is just beginning...
What have you learned about the layers of the earth?
Did you record anything interesting on the front of your foldable?
Are you excited for the next piece of the puzzle?
I was afraid of that...
Oh well...away we go!
The idea of Pangea & continental drift...
So in summary...
Now isn't that just an ocean of new, fun, and interesting facts!
Did you record the new things you learned on the front of your foldable???
Are you ready for more?
I knew you would be...
It will all start coming together now...
But before we can really break this apart...
We need to understand...
Just exactly what makes this earth of ours tick...
Within the asthenosphere, lays the answer to the earth's constant movement...
As well as the answer to all of your questions regarding convection currents on the back of your foldable...
Convection currents are caused by the very hot material at the deepest part of the mantle rising, then cooling, sinking again and then heating, rising and repeating the cycle over and over.
The next time you heat anything like soup or pudding in a pan you can watch the convection currents move in the liquid.
When the convection currents flow in the mantle they also move the crust. The crust gets a free ride with these currents. A conveyor belt in a factory moves boxes like the convection currents in the mantle moves the plates of the Earth.
Click on the following links to learn more about convection currents!
It's the same idea in a lava lamp...
But I don't understand...
What does all of this molten rock rolling around in the earth have to do with me??
Why do I need to know this?
What effect will this ever have on me?
But what is all this about tectonic plates and plate boundaries...?
Can you be more specific???
You knew I could be...
So there it is...
Everything you could need to know about our ever-changing Earth...
All that is left...
Is for you to show me what you know...
Your foldable should be COMPLETE...
And with it, you will have all you need to demonstrate that you have come away with something new...
You will soon be required to take a quiz over
this material...
This is for a grade...
And you only get one shot...
Take a look at the map of volcano eruptions & label these on your foldable...
Don't forget to plot earthquakes as well...
Check out this link!
Label BOTH the Ring of Fire and the Mid Atlantic Ridge on the same map where you drew the arrows showing the direction different plates were moving!
To be more specific..
The earth's continental crust is:
Average Density: 2.7 g/cm3
20-25 miles (30-40 km); thickest = 45 miles (70 km)

Consists mainly of igneous rocks
Upper layer: granite rock (lightly- colored, coarse-grain, magma)
Lower layer: basalt and diorite (same composition as granite)
The earth's oceanic crust is:
Average Density: 2.7 g/cm3
4-7 miles (6-11 km) below earth's surface & THICK
Made up of: Basalt rock (dark, fine-grained, gritty volcanic rock)
The earth's upper mantle is:
Bottom layer = tough liquid rock
Upper layer = stiffer liquid rock (because of lower temp)

Average Density: Between 3.4 and 4.3 g/cm3

7 to 190 miles (10 – 300 km) below the Earth’s surface

Made of silicates of iron and magnesium

And is 2520-5400 degrees F (1400 – 3000 degrees C)
The earth's lower mantle is:
Average Density: Between 4.3 and 5.4 g/cm3
190-1800 miles (300-2890 km) below the Earth’s surface
Made of sulphides and oxides of silicon and magnesium
Avg. temp. = 5400 degrees F (3000 degrees C)
The earth's outer core is:
Liquid (because is so hot)
Average Density: Between 10 to 12.3 g/cm3
1800-3200 miles (2890-5150 km) below the Earth’s surface
Made of iron and nickel (about 10% sulfur and oxygen)
And is... 7200-9032 degrees F
(4000-5000 degrees C)
The earth's inner core is:
Solid (pressures are so great that it cannot melt even though it is so hot)
Average Density: About 15 g/cm3
3200-3960 miles (5150-6370 km below the Earth’s surface)
Made of iron and nickel (some lighter elements)
And is 9032-10832 degrees F (5000-6000 degrees C)
Click on the following link to explore the types of plate boundaries.

Be sure to click on ALL 3 arrows.
Check out this link to learn more about the lithosphere and the asthenosphere:

Did you know that about 90% of the world's earthquakes and 81% of the world's volcanoes occur along the Ring of Fire???
How about the fact that the Ring of Fire contains over 450 volcanoes and is home to approximately 75% of the world's active volcanoes???
That's just nuts!!!!!!!!!!
Check out any of these earthquake video clips!
Watch any of these volcano clips!
Play either one of these games!
Plate Tectonics Game Show
Plate Tectonics Game
Japan Earthquake: Helicopter aerial view video of giant tsunami waves
New dramatic video: Tsunami wave spills over seawall, smashes boats, cars
Japan earthquake makes skyscraper dance
Eruption at Kilauea in Hawaii
Kilauea Volcano Erupts - Dramatic Video
Iceland Volcano erupts - Dramatic Video
Etnatao: Icelandic Volcanoes
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Full transcript