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24 terms

Plate tectonics

Chapter 6 of our textbook (physical AND online versions)
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tectonics
The branch of geology that deals with the movements that shape the Earth's crust.
Earth's crust
Earth's outermost layer.
Earth's mantle
Earth's thickest layer made of hot rock. It is less dense than the core, not as hot, and has less pressure on it. It begins approximately 6 miles below the Earth's surface.
Earth's core
The central part of the Earth. it is divided into an outer liquid section and an inner solid section. it is believed to consist mainly of nickel and iron. These two metals react with each other and cause it to be a temperature of 5000C
lithosphere
Earth's crust and solid upper mantle, broken into tectonic plates
asthenosphere
The layer below the lithosphere. Soft part of the mantle that moves very slowly.
outer core
The liquid portion of the core.
inner core
The solid center of the Earth. It is made up almost entirely of iron.
The theory of continental drift
says all continents were once joined together in a single landmass and are slowly moving even today.
seafloor spreading
The process that creates new sea floor as divergent plates move away from each other at the mid-ocean ridges
magnetic reversal
a switch in the direction of Earth's magnetic field so that the magnetic north pole becomes the magnetic south pole and the magnetic south pole becomes the magnetic north pole.
The theory of plate tectonics
says that the Earth's lithosphere is divided into large slabs we call tectonic plates. There are about 12 large plates and several smaller ones.
convection
Movement caused within a fluid by the tendency of the hotter fluid and therefore less dense material to rise. The colder fluid is more dense and will sink. This is thought to be the cause of continental drift.
divergent boundary
A plate boundary where two plates move away from each other.
convergent boundary
A plate boundary where two plates move toward each other
transform boundary
The boundary between tectonic plates that are sliding past each other horizontally.
Wegener
The scientist who proposed the idea of continental drift in 1912.
Pangea
The large supercontinent that existed 250 million years ago. It consists of all the continents that exist today.
folding
When rock layers bend due to the pressure caused by plate tectonics.
fault
A break in Earth's crust where slabs of rock slip past each other.
volcanic mountains form
when magma erupts onto the Earth's surface forming a new mountain. These usually form over convergent boundaries.
subduction
one tectonic plate goes under another tectonic plate, usually causes volcanoes to form.
dome mountains form
when a massive amount of magma pushes the layers of rock upward.
Earth's magnetic field is caused by
the outer core rotating in one direction, and the inner core rotating in the opposite direction at a different speed.