Plate Tectonics

Theory

Who started the theory? Alfred Wegener (pronounced, “Vagener”)

http://blue.utb.edu/paullgj/physci1417/Lectures/Plate_Tectonics.html

Wegener noticed that continents fit together like puzzle pieces. He proposed a theory that the continents moved over time, called the “Theory of Continental Drift.”

Six types of evidence noted by Wegener are shown here. The next several slides explain the evidence. Complete your chart showing how the evidence supports the Theory of Continental Drift.

Glacial Evidence

Places with warm climates have evidence that they were once covered by icy glaciers.

Some of these places are too hot to have glaciers today.

If the continents were together at the south pole (as shown above), they could have been cold.

This supports the theory by showing that the continents have moved from the south pole to the present-day locations.

Scratches on rocks show glacial movement

U-shaped valleys show the passage of glaciers in the past that tore away mountain sides.

http://www.indiana.edu/~geol116/week7/platefit.jpg

Fossil Evidence

Matching fossils of plants and animals are found on continents that are very far apart today. This supports the theory because it looks like those places with matching fossils used to be together.

Mountain and Rock Evidence

In many places, mountain chains and rocks on different continents match up. This supports the theory because it looks like they used to be together.

Coal Field Evidence

Coal fields in Europe match up with coal fields in North America. This makes it look like they used to be together

Alfred Wegener’s Theory of Continental Drift was not accepted by scientists of his time. His theory was rejected because he could not explain what force could be moving the continents.

He died in 1930 on an expedition in Greenland. When the Theory Plate Tectonics was developed in the 1950’s, Alfred Wegener was given credit for proposing the original idea.

http://en.wikipedia.org/wiki/Alfred_Wegener

http://www.awi.de/en/news/press_releases/detail/item/greenlandic_special_stamp_featuring_alfred_wegener/?cHash=4735140cb3e8f5bacb15e1ef3880f82b

Modern evidence supporting the Theory of Plate Tectonics

The next slides provide support for the Theory of Plate Tectonics. This theory states that the Earth’s crust is made out of plates that move around on the surface of the globe.

Use the slides to complete the chart.

Volcano locations show us where plates meet.

Volcanic Evidence

Click the link below to view current earthquake data:

Current earthquake locations also show where plates meet.

Current earthquake locations also show where plates meet.

This map shows worldwide earthquake locations. The locations show the edges of the plates that make up the earth’s crust. Click this link to view the latest version of this map: http://neic.usgs.gov/neis/qed/

Over time, earthquake locations form patterns that show plate boundary locations.

GIS Evidence: GIS allows us to gather data on movement of plates. Each spot is monitored using GPS, and we can measure the movement

over time.

On the map to the left, longer arrows show faster movement and shorter arrows show slower movement. Arrows also show direction of movement.

This map shows the direction of movement of the plates.

This shows how the locations of the continents has changed over time.

Plate Boundary Types

A plate boundary is a place where the edges of different plates meet. Follow this link to learn about the different types of plate boundaries. Complete the Plate Tectonics Boundaries Chart. Note that on this website, Transform Plate Boundaries are called “Conservative” boundaries.

http://scign.jpl.nasa.gov/learn/plate.htm

Three types of plate boundaries are shown here. Use this to begin your chart on plate boundaries, along with the next several slides.

http://www.suu.edu/faculty/colberg/Hazards/PlateTectonics/PlateBoundaries.jpg

As you examine the next several slides, find the types of land features that are found at each of the 3 plate boundaries. Add them to complete

your chart.

Divergent Plate Boundary

Divergent plates Convergent Plates

Video Clip – click below

How did plate tectonics affect our area? As plates pushed together, the mountains formed.

Folding during the Alleghenian mountain-building episode

Post mountain-building erosion to the ridges and valleys seen today.

The road cut through Sideling Hill shows how layers of rock that were once flat were deformed when plates pushed together.

Frederick

Middletown

Mountains

Washington County

Notice the wrinkle-shaped mountains running through

western Maryland.

Plate tectonics video clip from The Discovery Channel