Title Page-pg. 43 Chapter 11 Deformation of the Crust • 3 pictures • 3 keyword • 3 colors
Which type of fault motion best matches the general pattern of crustal movement at California’s San Andreas Fault? • Diagram 1 • Diagram 2 • Diagram 3 • Diagram 4
In: pg. 44 • Deformation means to change shape, to go away from the normal What are 3 examples of deformation of the Earth’s crust?
Stress • Amount of force per area put on an object
Stress Stress-The squeezing, stretching and twisting of the Earth’s crust.
Isostasy • Isostasy-The balance between the downward pull of gravity on the lithosphere and the upward push of the asthenosphere. • If the mass of the crust increases, it sinks. • New mountains, glaciers, sediment deposition • If the mass of the crust decreases, it rises. • Erosion of mountains, melting of glaciers
The weight of the crust pushes down on the asthenosphere. • As the mountain erodes away, the crust gets lighter and rises. The deposition of sediments causes the crust to sink.
Three types of stress: Compression Tension Shear
Stress Types of stress: • Compression-Pushing together • Tension-Pulling apart • Shear stress- sliding in opposite directions
FOLDING • Rock layers bend due to stress • Assume most rocks are laid down horizontal
Folds Fold-bend in rock layers. • Happen below the earth’s surface where it is warmer Anticline-folds upwards Syncline-folds downwards
FAULTS • The line along which rocks break and move
Faults • Hanging wall-The rock above the fault • Foot wall-The rock below the fault
Normal Faults • Caused by tension forces • Hanging wall moves down
Reverse Faults • Caused by compression forces • Hanging wall moves up
Strike-slip Faults • Opposing forces cause rock to break • Move horizontally
Types of Faults • Normal Fault-hanging wall move down, footwall moves up. • Caused by tension stress
Reverse Fault-hanging wall moves up, footwall move down. • Caused by compression stress • Strike Slip Fault-rock on either side of the fault slides horizontally past each other in opposite directions. • Caused by shearing stress
Follow-Up Questions Does the shape of the marshmallow lengthen during compression or tension stress? What happens to the shape of the marshmallow during shear stress? Describe the differences between the three types of stresses that can occur to rocks as the lithosphere moves.
Answers 1.Tension stress. 2.Shear stress pulls the marshmallow in more than one direction. 3.Compression stress squeezes and shortens rocks, tension stress pulls rocks apart, and shear stress distorts the shapes of rocks.
How Mountains Form Mountain Range-A group of mountains that are close together and formed together. example: Cascade Range, Great Smokey Mountains, Rocky Mountains
Mountain System-A group of mountain ranges that are close to each other. • Example: The Appalachian Mountain system.
Thru 2 Pg. 46 Ch. 11 3 Column Vocab • Deformation • Isostasy • Stress • Compression • Tension • Shear stress • Fold Pg. 47 8. Anticline 9. Syncline 10. Fault 11. Footwall 12. Hanging wall 13. Mountain range 14. Mountain system **Not all words are in glossary, some are italicized in the chapter or in notes.
Out • Less than five million years ago, the range that we now know as the Sierra Nevada began to rise. Through a combination of uplift of the Sierran block and down-dropping of the area to the east, the Sierra rose upward. The entire Sierra Nevada can be thought of as an enormous tilted fault block mountain with a long, gentle slope westward to California's Central Valley and steep eastern slope towards Nevada. • When did the Sierra Nevadas start to uplift? • Where are the Sierra Nevadas located? • What type of mountains are the Sierra Nevada Mountains?
In Use your notes to answer these questions. • _______ is the balance between the crust and the asthenosphere. • If a mountain is eroded away, will the crust move up or down? • What are the 3 types of stress? • _______ stress results in rock being pushed together. • What are the 2 types of folds? • A _______ fault is caused by compression stress. • In a _______fault, the rock on either side of the fault slides horizontally in opposite directions. • The Rocky Mountains are an example of a mountain_______. • What are the 4 types of mountains? • Which type of mountain forms from compression stress?
Thru 1: Pg. 49 Movie: Shaping the Planet