Alfred Wegner is the scientist who came up with the theory of the Continental Drift. The Continental Drift is the theory that all of the continents were once all one large body of land called Pangea. Also, that the continents move as time goes by, but these movements are very small. There are 10 different plates that make up the land above and below the oceans, know as continental and oceanic.
Transform Boundaries are when two plates slide past each other horizontally. When the plates slide past each other, they grind, jerk, and have tension. This is known as shearing. It is also called a strike-slip fault.
Convergent Boundaries are when two plates push into each other, this is also known as subduction. When two continental plates push into each other it makes mountains. When an oceanic plate and a continental plate push together, the oceanic crust goes under the continental crust because the density of the oceanic crust is more dense.
Divergent Boundaries are when two plates pull away from each other, also known as tension. An example is the Mid-Atlantic Ridge. The Mid-Atlantic Ridge pulls apart, then magma rises to fill in the open spot, creating new oceanic lithosphere. The spreading apart of ocean floor is called sea-floor spreading.
This is an earthquakes epicenter. The epicenter is on the Earth's surface, directly above where the earthquake started. The cause of earthquakes happen when two plates pull, push, or scrape against each other . Stress builds and the rock of the plate deforms. The Richter Scale is used to measure the magnitude of an earthquake. A Seismograph is an instrument at or near the surface of the Earth, that records seismic waves. There are two types of waves, primary waves and secondary waves. Primary waves go through solids, liquids, and gases, and move the fastest. Secondary waves are solid waves, and go slower. They shear rock back and forth as they go through it.
Volcanoes are mountains that form when molten rock, magma, is forced to the Earth's surface. There are two types of volcanic eruptions, nonexplosive and explosive. Nonexplosive eruptions create lava flows, which is when lava just flows out of the volcano. Explosive eruptions are when gas and clouds of hard debris shoot out of the volcano. Instead of creating lava flows, molten rock is blown into millions of pieces that harden. There are three types of volcanoes, shield, cinder cone, and composite. Shield volcanoes are created from layers of lava from repeated lava flows. This volcano is very runny and has sloping sides. Cinder Cone volcanoes are small volcanoes made out of pyroclastic material from moderately explosive eruptions. They are steeper and have a narrower base. They erode quickly because they are not cemented together with lava. Composite volcanoes are the most common type of volcano, also called stratovolcanoes. Form by explosive eruptions followed quieter outpourings of lava. They switch off from nonexplosive and explosive.