Plate Tectonics By: Brad Bardua
History of Pangaea Alfred Wegener In 1912, Alfred Wegener proposed that the continents were once a single supercontinent called Pangaea- he thought the continents drifted apart later on to form the continents that we have today Alfred got his PhD in astronomy from the University of Berlin- knowing astronomy probably helped his discoveries because he would know a lot about the atmosphere His hypothesis lacked a geological mechanism to explain how the continents could drift across the Earth’s surface- many scientist didn’t support this theory He later then found a paper that said that a land bridge once connected Africa with Brazil- the founding of this paper helped support his theory a little more
More About Alfred Alfred’s theory sparked a discussion called the “Contraction theory” which believed that the planet was a molten ball and when it was in the process of cooling the surface cracked and folded up on itself To help Alfred out with his theory Arthur Holmes assisted him by spreading the idea that the mantle does undergo thermal convection Later on Henry Hess and R. Deitz made hypotheses based on the mantle convection currents which are now known as “sea floor spreading”- these ideas helped Wegener’s findings have more evidence to further develop and support the idea
Pangaea The supercontinent was named Pangaea because the word Pangaea means “all lands” Pangaea was said to have been made during the Carboniferous period which was 300 million years ago Also, Pangaea was located near the south pole according to Alfred Wegener
Convergent Boundaries A convergent boundary is where plates moving in opposite directions meet each other and one plate goes down beneath the other Sometimes convergent boundaries are called subduction zones One example of a convergent boundary would be where the Pacific Plate is being subducted under the North American Plate
Hazards 1. Earthquakes- form on the outer parts of the plates 2. Volcanoes- (above sea ones) form where the subduction occurs 3. Trenches- form after conversion 4. Tsunami Waves can also form
Divergent Boundaries A divergent boundary is where 2 close plates pull apart which causes sea-floor spreading (can also be called spreading) An example of this boundary would be where the Mid-Atlantic Ridge separates the North and South American Plates from the Eurasian and African Plates
Hazards 1. Mountains- form when there is a divergent boundary 2. Shields of the volcanoes and earthquakes also form because of this boundary
Transform Boundaries A transform boundary is where one plate slides past another in a horizontal direction An example of this boundary would be where the San Andrea fault zone of California marks the boundary between the Pacific and the North American Plates
Hazards 1. Volcanoes and earthquakes form 2. Mudslides and Landslides also form because of transform boundaries
Real World Connections Have you ever wondered what plate we live on? Well we live on the North American Plate which is above the Caribbean Plate, South American Plate, and the Juan de Fuca Plate To the east and west is the Eurasian Plate
U.S. Hazards The U.S. could be in serious hazard dangers because in Ohio there were at least 200 earthquakes in one year There are 3 main areas in Ohio which could have problems which is in Northeastern Ohio, Southeastern Ohio, and Shelby County- these were where most of the earthquakes in Ohio happened Also, California can be in big trouble because of the San Andreas Fault which has caused many earthquakes- the 2 plates that make up this fault are moving 6cm per year so that means a huge earthquake could happen soon
The Future I think that the U.S. will be destroyed in the years to come due to plate tectonics because their will be more earthquakes, volcanoes, landslides, mudslides, and hurricanes
Bibliography http://www.ucmp.berkeley.edu/geology/techist.html http://www.ucmp.berkeley.edu/history/wegener.html http://vulcan.wr.usgs.gov/Glossary/PlateTectonics/description_plate_tectonics.html http://geology/plate-tectonics.shtml