Plate Tectonics

By: Clara Michael

Types Of Plate Movements & What They Do

Transform - The plates rub together creating earthquakes & fault lines. (Ex; San Andres Fault )

Divergent (ocean ) - The plates are pulling away from each other, which causes seafloor spreading, earthquakes & volcanoes. (Ex; Mid Atlantic Ridge)

Divergent (continents) - Plates are being pulled away from each other, creating rift valleys, earthquakes & volcanoes. (Ex; African Rift Valley & Icelandic Rift Valley.)

Convergent subduction - Plates are pushing together, and being pulled down, creating trenches & volcanoes (Ex; Marinas Trench & Ring Of Fire .)

Convergent Continents - Plates are being pushed together, since they have equal densities they are forever upward, creating folded mountain ranges (Ex; Himalayan Mountains.)

Layers Of The Earth & Their importance

Core - The core is the very center of earth, made of mostly iron and nickel- iron alloy. The core moves at a different speed than earth, and is also thought to contribute to Earth's magnetism.

Mantle - The "middle layer", is composed mainly of ferro magnesium silcates. This is where most of the internal heat of earth is located. Large convective cells circulate heat and are thought to drive the tectonic plate process.

Crust- The crust is the outer layer of earth, which is basically a thin shell of rock, encasing all the molten heat in the mantle. The crust is mostly made of sedimentary rocks, dirt, sand, and alumio-silcates.

Continental Drift Theory, Evidence, Who created the theory

Alfred Wegener, a German scientist fully developed the rest of this theory in 1912. His idea was rejected because of lack of "mechanism".

The original theory was in 1858 Antonio Snider-Pellegrini created two maps demonstrating how America and Africa may have once fit together then separated.

The theory of continental drift is that one point in time, a LONG time ago, all the continents fit together to form one super continent, called Pangaea, but due to plate tectonics, they drifted apart.

Evidence of this theory is that all the continents look like they would fit like puzzle pieces, and also similar fossils found in one continent where found on a different continent.

Sea Floor Spreading, Who Discovered it & How does it explain continental drift.

Sea floor spreading is caused my divergent boundaries.

It's a process that occurs at mid-ocean ridges when new crust forms.

The idea of sea floor spreading was thought by Harry Hess during the 1960's.

It explains & contributes to continental drift because sea floor spreading happens when the plates move apart, which it goes along with the continental drift theory, that the continents moved apart.

The Ring Of Fire

The ring of fire is a place where there are a large number of volcanoes and earthquakes occur, at the basin of the pacific ocean. It has 452 volcanoes and has 75% of the world's active volcanoes. 90% of the worlds earthquakes occur in the ring of fire. The ring of fire was caused by plate tectonics. The Eastern side was caused by the Nazca Plate and Coco plate being subducted. The western side was caused by the Coco's plate being subducted under the Caribbean plate.
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