Can you feel the earth move under your feet?

I can explain the effects of plate tectonics as they are relate to density, force, mountain building, fossils, and magnetic evidence.

In 1912 Alfred Wegener proposed the Continental Drift Theory

Pangaea video

He noticed that Africa and South America looked as they fit like puzzle pieces.

Image Source: Blue Sky GIS: Maps in comics: August 2012

In 1912 Alfred Wegener proposed the Continental Drift TheoryFOSSILS plants and animals found on what are now separate continents separated by oceans

Which do you think is the most logical explanation for fossils found on separate continents.

Image Source: The Concept of Geosciences

In 1912 Alfred Wegener proposed The Continental Drift Theory

Paleoclimate data-

Which is geological history stored in rocks. For example an ice sheet had once advanced from Southern Africa to India, a phenomenon impossible to explain given the modern arrangements of the continents.

Image source: The Concept of Geosciences

People had a hard time believing Wegener's theory because he couldn’t explain how the continents move

Image Source: Hudson Valley Geologist Blog

What we know now…

Our planet: A cross sectionCrust:

Continental- 12-25 miles

Oceanic- 3.1-4.9 miles more dense than continental crust.

Mantle:

Approx. 1800mi more dense than the crust. Geological events such as earthquakes and volcanoes give us clues that the upper portion is rigid like the crust but the lower portion is plastic-like easily deformed.

Outer Core:

Very hot about 9000 iron and nickel should boil and turn into a gaseous form but remain liquid because of the pressure from the mantle keeping the atoms close together.

Inner Core:

Temps exceed 9000 but the metals remain solid because of the intense pressure forcing the atoms side by side.

Image source:

Sussex House Geography Department Wikispace

The Upper mantle is divided into 2 sections:Lithosphere and Asthenosphere

Lithosphere:

Approx. 60 mi thick made up of the crust and upper portion of the mantle. Made up of about 7 large pieces and several smaller pieces called tectonic plates.

Asthenosphere:

Hot plastic-like portion of the mantle, soft and easily deformed, like a piece of gum .

What puts the continents into motion?

Due to the Radioactivity of Uranium, Thorium and Potassium in the Earth core an immense amount of Energy is released in the form of Heat.

This heat creates convection currents causing movement in the plastic-like asthenosphere. (Think boiling oatmeal) This movement causes the lithosphere/tectonic plates to “float” atop the gum like asthenosphere.

Click Here for a video representing this phenomenon.

Image Source:

Windows to the Universe

Did You know? Plates move about 3 inches per year. That’s about as fast as

a fingernail grows.

Image source: http://www.gweaver.net/techhigh/sci-eng%20data.htm

Evidence that the tectonic plates are moving

Three types of Plate Boundaries:

Image source: age-of-the-sage.org

Did you know? Los Angles sits on the Pacific plate that is moving northwest

and San Francisco sits on the North American plate that is moving southeast. Moving towards each other at the rate of 5cm (2in) a year, someday these two cities may be neighbors.

Image Source: USGS

Which type of boundary is this?Divergent Convergent Transform

Two plates move apart, creating a gap between them. When this happens, hot rock rises from the asthenosphere and cools, creating new lithosphere.

Rift ValleyMid-Oceanic Ridges

Two plates collide

MountainsTrenchesVolcanoes

Two plates sliding past each other

FaultsEarthquakes

Image Source: Holt Physical Science Book, 2006 pg. 705-707

Mountains forming at Convergent plate boundaries

Mountain Formation video

Do you agree that phenomena such as mountains increasing in height, volcanoes erupting, and earthquakes help with the theory that the continents/plates are moving?

Did you know?

The tallest mountains in the world are still growing. About 60 million years ago, the Himalayan Mountains formed when the Indian Plate crashed into the Eurasian Plate. Today the two plates are still colliding and the Himalayans continue to rise.

Image Source: Dylan Prentiss, Department of Geography, University of California, Santa Barbra

Sea floor spreading

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Seafloor Spreading Animation

Harry Hess, a Princeton geologist proposed in 1962, that Seafloor spreading was the driving mechanism for Wegener’s Continental Drift Theory.

Magnetic evidence in the new rock made at Mid Oceanic Ridges

Magnetic Evidence in rocks on the Seafloor

Further proof for Hess’s Seafloor spreading theory

Ongoing Recent Evidence

Satellite Technology

GPS and other satellite based collection techniques, scientists can measure the velocity of plates on Earth’s Surface. It is recorded that they move 10mm to 100mm.

Explanations for Geological phenomenon

Himalayans still rise at the rate of 1cm per year. We can also explain marine fossils at the top of these tall mountains.

1. The earth’s rotation is what causes the lithosphere’s tectonic plates to “drift” True

False

False, tectonic plate movement is due to the Energy released in the form of heat from the radioactivity in the Earth’s core causing convention currents in the asthenosphere putting the plastic like layer in motion allowing for movement of the lithosphere.

2. Which of the following was evidence Wegener used for his Continental Drift theory?

A. Africa and South America looked to fit together like a puzzle.

B. Fossils of plants and land animals were found on continents separated by oceans

C. Similar Glacial Ice found on separate continents

D. All of the above

3. Which of these layers of the earth is the least dense?

A. Mantle

B. Inner Core

C. Oceanic crust

D. Continental Crust

4. Mountains form at which type of boundary?A. Divergent

B. Convergent

C. Transform

5. Mid-Oceanic Ridges, the source of sea-floor spreading, are located at which type of boundary?

A. Divergent

B. Convergent

C. Transform

6. Earthquakes occur at Which type of boundary?

A. Divergent

B. Convergent

C. Transform

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