KGMK+2.1

toc =2.1 Earth's Crust in Motion=

vocabulary

 * earthquake**:the shaking and trembling that results from the movement of rock beneath the surface
 * stress**:powerful forces that squeeze or pull the rock in the crust
 * shearing**:stress that pulls two masses of rock in the opposite direction
 * tension:**pulls on the crust
 * compression**:squeezes rock until it folds or breaks
 * deformation:**a change in the volume
 * fault**:a break in Earth's crust
 * strike-slip fault**:shearing makes a strike-slip fault
 * normal fault:**tension makes normal faults
 * hanging wall:**the top half of the fault
 * footwall:**the bottom half of the fault
 * reverse fault:**when the blocks move the other direction
 * fault-block mountain:**normal faults raise up chunks of rock
 * Folds:** to lay a part over or against another part
 * anticline:**an arch of layers of rock in the Earth's crust
 * syncline:**bends downward on the Earth's crust to form bowl shape
 * plateau:**a large level area of high flat land

Stress in the crust

 * when there is too much stress between two plates a earthquake will happen
 * the energy can stay for a long time until it is released
 * stress is a force and therefore adds energy to rocks
 * when the energy is stored inside the rock until it changes shape or breaks

Types of stress

 * there is shearing, tension, compression
 * it takes millions of years to change the shape and volume
 * other rocks may be softened by the heat from the sun or slowly bend like road tar
 * Shearing could cause rocks to separate into parts and slip, shearing may also cause the rock to change shape.

Kinds of faults

 * the strike-slip fault, normal fault, reverse fault they are the main types of faults
 * when there is too much stress that builds up in a rock, the rock may break, and that can create a faults

Strike-Slip Faults

 * shearing is what makes strike-slip faults
 * how strike-slip faults are made is when the ground on either side of the fault slip past each other sideways with some up and down process
 * strike-slip faults form boundaries between two plates that is called a transform boundary
 * Example: The San Andreas fault in California is an example of a strike-slip fault and it is a transform boundary

Normal faults

 * tension in Earth's crust may cause normal faults
 * normal faults is at an angle so one pile of rocks lies above other piles that lie below the fault
 * tension create normal faults where plates diverge or they are pulled apart
 * Example: normal faults occur along the Rio Grande rift valley in New Mexico, that is where two pieces of the Earth's crust are divergent

Reverse Faults

 * compression forces make reverse faults
 * its close to a normal fault but the hanging wall it above the foot wall
 * Example: Appalachian Mountains in the eastern United States that is part of a reverse fault
 * over millions of years the hanging wall or the foot wall and one of them will have to overlap each other
 * that soon would wore away leaving only the mountain peaks

Friction along faults

 * if two plates get stuck for a long time stress will build and when it is released big earthquake will happen


 * if plates push against each other it will slowly push up and form a tall mountains[[image:KGMK.jpg width="470" height="276"]]