PLATE TECTONICS WEBQUESTBy: Jacob Fisher

The History of Pangaea The word Pangaea, meaning “all lands”, is the word that describes the

supercontinent that the world once was. The theory of Pangaea was originated from a man named Alfred Wegener. Wegener believed that Pangaea existed about 300 million years ago, during

the Carboniferous period. The idea of the world once being a supercontinent was not originally

accepted by scientists, mainly because the forces from the earth that were generated by its rotation were calculated insufficient to move continents.

During 1912 when Wegener calculated this theory, the Contraction Theory was also being tested by other scientists.

The Contraction Theory suggested that the earth was once a molten ball, and during the process of cooling, the surface folded up on itself.

Wegener studied geophysics and meteorology as well as science. His studies could have caused him to believe that the continents moves just like stars and clouds do.

Arthur Holmes elaborated on one of Wegener’s hypotheses, stating that thermal convection in the earth was like a conveyor belt; upwelling pressure could break up a continent and force the broken pieces in opposite directions with convection currents.

Alfred WegenerTo the right is an image of Alfred Wegener, the man who invented the theory of our supercontinent, Pangaea. Wegener was a scientist, a meteorologist, and a geophysicist.

Convergent Boundaries

A convergent boundary is an area between two or more colliding tectonic plates. Convergent boundaries are subduction zones, which is an area in which one plate is pushed underneath another when they collide. This is what creates mountains. Often when two plates collide and form a convergent boundary, they create frequent, powerful earthquakes. There are many convergent boundaries all over the world that you don’t even notice. For example, the Indian plate is currently crashing into the Eurasian plate, which is forming the Himalayas. India and Eurasia are two separate plates from Pangaea, many billions of years ago.

Divergent Boundaries A divergent boundary is the exact opposite of a convergent

boundary. With a convergent boundary, the plates collide to form earthquakes and mountains, which become volcanoes, normally. However, with a divergent boundary, the plates pull apart from each other. This is possibly associated with thermal convection, where forces within the earth acted like a conveyor belt, and upwelling pressure causes the plates to move in opposite directions. Examples of divergent boundaries in the world today would include the mid-Atlantic Ridge. The plates are pulling apart, which causes sea floor spreading (makes the size of the sea grow). Divergent boundaries cause earthquakes, just like convergent boundaries do, but they also cause volcanoes. This is because they open up the crust of the earth, (which is what causes things like geysers, too).

Transform Boundaries A transform boundary occurs when two plates slide against

each other in opposite directions. This forms a fault line, such as the one found in San Andreas, CA. You’ve probably heard of the San Andreas fault in California. If not, you now know that the famous fault line found there overlays a transform boundary. The fault line is the boundary where the plates are sliding against each other, because it is the plates that create that fault line. Transform boundaries can cause many natural disasters, some of which include volcanic activity and earthquakes, which can lead to landslides and avalanches. This is because the force of the plates scraping against each other can be destructive to the world above it.

What about US? We live on the North American Plate, which covers the majority of North

America. California is overlaying the Pacific plate. The Caribbean Plate, the Pacific Plate, and the Cocos plate surround the

United States and the North American Plate. The only threats that US citizens are prone to due to tectonic plates are

natural disasters, such as earthquakes, mudslides, volcanoes, landslides, and avalanches. Ohioans face the same things, because we are on the same tectonic plate as the rest of the US.

I believe that within the next few years, it is very possible that California will break off of the Unites States and into the sea. This is because it is on a separate plate than the rest of North America. It is also on a fault line, which makes it prone to earthquakes.

Mudslide (to left)

Boundaries

This is an image of the mid-Atlantic Ridge. It is a divergent boundary, and therefore, sea floor spreading is found here.

This is an image of the Queen Charlotte fault and its surrounding region in North America. It is a transform boundary, so it is ever-changing depending on how much the plates shift.

The above image is that of the Himalayas; the area between India and the Eurasian plate. It is a convergent boundary because the Indian plate is subducting under the Eurasian plate, causing the Himalayas to be made.

Background: Mariana Trench

The End!

Special thanks to:http://geology.com/plate-tectonics.shtml

http://www.ucmp.berkeley.edu/geology/techist.html

http://scign.jpl.nasa.gov/learn/plate2.htm

http://vulcan.wr.usgs.gov/Glossary/PlateTectonics/description_plate_tectonics.html

http://www.platetectonics.com/

Garfield!