Plate Tectonics

By: Caleb Brooks


1. The three layer of the Earth are the crust, Mantle and the Outer and inner core. The crust is for "Within the crust, intricate patterns are created when rocks are redistributed and deposited in layers through the geologic processes. The crust is composed mainly of alumino-silicates." "The mantle is a dense, hot layer of semi-solid rock approximately 2,900 km thick and is composed mainly of ferro-magnesium silicates. This is where most of the internal heat of the Earth is located. Large convective cells in the mantle circulate heat and may drive plate tectonic processes." " Below the mantle is the core. It makes up nearly one third the mass of the earth. The Earth's core is actually made up of two distinct parts: a 2,200 km-thick liquid outer core and a 1,250 km-thick solid inner core. The outer core is made of iron and is very dense. As the Earth rotates, the liquid outer core spins, creating the Earth's magnetic field. The inner core is made of solid iron and nickel. Many scientists believe it is kept in the solid state because of the extreme pressure from the other layers."

2. Continental Drift is when the continents are moving and will never stop because of the tectonic plates.

3. There were actually two people who came up with the hypothesis. Their names were Abraham Ortelius and Alfred Wegener.

4. One piece of evidence is that if you look at the continents they can fit together like a jigsaw puzzle. Also a biologist found two of the same fossils in South America and Africa.

5. Sea floor spreading is when the crust of the ocean is breaking apart and lava is coming up.

6. Harry Hess's discovery led to even greater ones. It was found out that the seafloor was warmer near the Mid-Atlantic Ridge. This was actually heat from the magma underneath it. This led to Harry Hess's even greater theory; seafloor spreading.

7. Seafloor spreading is a process that occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity and then gradually moves away from the ridge.Seafloor spreading helps explain continental drift in the theory of plate tectonics.

8. Convection helps with plate movement by "Plates at our planet’s surface move because of the intense heat in the Earth’s core that causes molten rock in the mantle layer to move. It moves in a pattern called a convection cell that forms when warm material rises, cools, and eventually sink down. As the cooled material sinks down, it is warmed and rises again."

9. The theory of plate tectonics is "Plate tectonics is the theory that the outer rigid layer of the earth (the lithosphere) is divided into a couple of dozen "plates" that move around across the earth's surface relative to each other, like slabs of ice on a lake.'

10. Transform boundaries are responsible for earthquakes because they make a movement like front to back. Divergent boundaries are responsible volcanoes because they split the ground open and magma comes up and makes volcanoes when the magma dries. Convergent are responsible for mountains because the the two plates combine the force make some of the rock and earth shoot up and make a mountain. Convergent and subduction are responsible for when one continental plate is denser than the other and they collide one pulls the other one under and creates a trench.

11. The ring of fire is a huge area comprising of many volcanoes in the pacific ocean, that accounts for approximately 80% of the world's seismic activity. It is a significant geological structure due to this, and contains a large majority of the world's volcanoes and volcanic activity. Contrary to it's name, the ring of fire is not actually a ring, but a horseshoe-shaped semi-ring.

12. Earthquakes can destroy whole cities and they are cause by transform boundaries. Volcanoes can also destroy whole cities and they are caused by divergent boundaries . Convergent boundaries are only responsible for mountains.


South America

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