General Science.

[Eh.]

Movement of tectonic plates is due to the hot, flowing condition of the asthenosphere. What is the term for semi-liquid condition? Plasticity. The asthenosphere as a whole flows slowly but consistently due to convection.

The outer core is liquid because temperature is the controlling factor.
The inner core is solid because pressure is the controlling factor.

The elements aluminum and silica are very abundant in the crust, especially in the continental crust. Though copper, silver, iron, and nickel are also found in the crust, their amount is much less compared to aluminum and silica.

The earth's core is made up of 90% iron and 10% nickel.

The solid lithosphere is made up of crust and a small part of the upper mantle.

Heat travels through a fluid via convection, where warmer molecules move upward and cooler molecules move downward. Conduction travels through a solid, radiation can pass through all states of matter and can also pass through a vacuum.

The continental crust is less dense than oceanic crust. High percentages of silicon, oxygen, and aluminum contribute to a lower density as these elements have small atomic masses. The oceanic crust is made up of heavier elements.

Basalt and gabbro (oceanic crust) are denser than granite and rhyolite (continental crust).

Discovered by Andrija Mohorivicic, the Moho boundary is the boundary of the crust and the mantle, Mohorivicic used seismic waves to determine this boundary. He observed that a certain depth, P (primary) waves and S (secondary) waves changed direction, indicating a change in the composition of the earth. This depth is therefore the boundary between the solid crust and the semi-liquid upper mantle.

The P wave is a longitudinal wave, wherein the wave vibrates forward and backwards as it travels forward. As it passes through rocks, the rock particles go with the motion of the wave; some are stretched (expanded) and some are compressed.

The S wave is a transverse wave wherein the wave oscillates from side to side as it travels forward.

The shadow zone is the boundary between the solid lower mantle and the liquid outer core. P waves can pass through both solid and liquid rock. S waves can ONLY pass through solid rock. When P waves hit the shadow zone, they bend due to the difference in composition of the mantle and core. When S waves hit the liquid outer core, they stop. The absence of the S wave makes it impossible for seismologists to detect earthquakes at the shadow zone.

Though the P wave can pass through both solid and liquid rock, it will change direction if it passes through the boundary between two earth layers, if these two layers have different properties.

Wave behaviour:
Reflection - bouncing back from a surface
Refraction - bending of a wave as it passes through a certain substance
Diffracton - a wave is scattered if it passes through a certain substance

When plates collide, the denser plate will move under the other plate. This is subduction. The plate that subducts will then sink into the mantle and melt.

Types of plate boundaries:
Divergent - plates move away from each other
Convergent - plates collide
Transform - plates slide in opposite directions beside each other

[...Oh em ji, I only reached #23. I GIVE UP.]