KTTM+2.1

= = toc back to home page =Earth's Crust in Motion=

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Vocabulary
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 * Earthquake**: the shaking of the rocks underneath the crust
 * Stress**: a type of energy that changes a rock's shape or volume
 * Shearing**: energy that pulls the weight of a rock in two opposite directions
 * Tension**: energy that pulls on the side of the rock making it skinnier in the middle
 * Compression**: a force that pushes pieces of rock together until it breaks
 * Deformation**: any change of volume or shape in our planet's crust
 * Fault**: a break in the Earth's surface where slabs of crust slip past each other
 * Strike-slip fault**: a fault where rocks on either side of the fault slip past each other sideways with a little up-and-down movement
 * Normal fault**: a fault where it's at an angle so one block of rock lies above the fault while the other block of rock lies below the fault
 * Hanging wall**: half of the fault that lies on top
 * Footwall**: half of the fault which lies on the bottom
 * Reverse fault**: a fault which has the same structure as a normal but the rock's direction are switched
 * Fault block mountains**: a fault that is created when a normal fault uplifts a block of rock
 * Folds**: bends in the rock that form when compression shortens and thickens part of Earth's crust
 * Anticline**: a fold in a rock which makes it bend upward into an arch
 * Syncline**: a fold in a rock which makes it bend downward to form a bowl
 * Plateau**: a large area of flat land made high above sea level

Stress in the Crust

 * there are three types of **stress in the crust**
 * **Shearing**
 * can cause rock to break or change its shape
 * **Tension**
 * stretches the rock which causes the middle to become thinner
 * **Compression**
 * squeezes the rock until it folds or breaks

Kinds of Faults

 * **Strike-Slip fault**
 * the rocks on either side have an up-and-down motion while they slip past each other
 * **Normal fault**
 * one block is on top and another is below, the top half of the fault is the hanging wall, the bottom half is the footwall
 * **Reverse fault**
 * same as normal fault but the rocks move in the opposite directions

Friction among faults

 * rocks in a fault move only if there is friction
 * friction exits because the surface is not smooth

Mountain Building

 * Mountains can be formed by faulting
 * Mountains can also be formed by folding
 * Anticlines and Syniclines
 * Geologists use these words to describe the upward an downward folds in rock
 * Plateaus
 * forces that raise mountains can also raise plateaus



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