By Ashleigh Sherman

The theory of Pangaea was originated by Alfred Wenger. He was also a meteorologist so he knew about the earth and weather. Pangaea is the theory that all the continents were connected at one point but now they have moved apart. Pangaea means “all lands.” Pangaea occurred during the Carboniferous period. At first the theory of a super continent was not originally accepted because there wasn’t any explanation why the continents moved or any evidence. While Alfred studied Pangaea another theory was discussed. It was the Contraction Theory. This theory was that the earth was once a molten ball, and when It cooled it cracked and formed continents and mountains. Later Arthur Holmes elaborated on the idea of Pangaea, and it was finally recognized. He thought that the mantle undergoes thermal convection and It creates a current strong enough to move continents. His ideas relate to Pangaea because they both believed in continental drift.

There are three different types of boundaries: convergent, divergent and transform. A boundary is a place where two plates meet. A plate is a huge, irregularly shaped slab of solid rock, made up of both continental and oceanic lithosphere.

A convergent boundary is when two plates moving in opposite directions meet and one is dragged down beneath the other. A lot of the time when plates converge an oceanic plate slides below a continental plate. Hazards from convergent boundaries are trenches, earthquakes and volcanoes. Trenches are deep holes in the ocean’s crust. They are formed when the ocean floor is scraped off against an over riding plate. Volcanoes are an opening in a plate's surface or crust which allows hot magma, volcanic ash and gases to come out of the crust. One of the most famous convergent boundaries is the Himalayas in India. It involves the Indo-Australian and Eurasian Plates.

Divergent Boundaries are two plates moving away from each other. As the plates move away from each other they create oceanic ridges. They are created when the magma comes up from a crack and cools. It pushes the two plates apart. Divergent boundaries can form tall mountains. Mountains are a natural rise of the Earth 's surface made up of crust. Divergent boundaries can also form trenches. The Mid-Atlantic ridge is a famous divergent boundary. It is made up of the North and South American plates and Eurasian and African plates.

Transform boundaries are plates moving by each other. One of the plates is moving horizontally past the other. A lot of earthquakes are formed with a transform boundary. An earthquake is a shaking and vibration at the surface of the earth because of underground movement of plates. They happen because of the accumulation and release of strain as the two plates slide past each other. Earthquakes can cause landslides and mudslides. A landslide is a mass movement of rock, earth or debris down a slope. A mudslide is moving rivers of rock, soil, and water. One of the most famous transform boundaries is the San Andreas fault in California. It is between the North American and Pacific plates.

We live on the North American plate. The North American plate is bordered by the Juan de Fuca plate, Caribbean plate, Coco’s plate, Pacific plate and North American plate. Ohio is a very earthquake prone zone. There have been over 200 since Nobody knows for sure what causes them but they think it’s because it’s a weak spot in the earth’s crust. California is also very earthquake prone because its on a plate border. The Hawaiian islands are made up of volcanoes. I think that in the future the U.S. and all the other continents will be smashed together because the plates are all moving closer together. I also think that there will be more natural disasters because the plates will all be close together.

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