Section 1 Notes
Forces in Earth’s Crust
(Page 44-45)
•Tension, compression, and shearing are different kinds of stresses and over millions of years they have changed the shape and volume of the rocks.
•Rocks are constantly under going a lot of stress through stretching and bending.
•Tension - stretches rock ( 2 plates are moving apart) forms a valley
•Compression – pushing rocks together ( 2 plates are moving toward each other) forms a hill
•Shearing – causes masses of rock to slip (2 plates that move pass each other in opposite directions)
(Page 46-47)
When a weak point is present it will create a break within the rock. The rock will then move and a fault will appear. These faults form along plate boundaries. There are 3 types of faults; Normal, Reverse, and strike-slip
•Normal faults- subject to tension. Tension will pull rocks apart. This fault is at an angle so one block of rock lies above the fault (Footwall) and the other block lies below ( Hanging Wall) (Divergent Plate Boundaries) (Rift Valleys) ( Great Basins) Two parallel normal faults will form folded mountains.
•Reverse faults- subject to compression. Compression pushes on rocks from opposite directions. This fault has one side of a reverse fault which lies at an angle above the other side. Unlike the normal fault the hanging wall is higher than the footwall. The faults are form at the Convergent Plate Boundaries. These faults form Mountain ranges. These faults create folds in the earth’s crust. They will form upward arches (Anticlines) ridges and downward arches (Synclines) valleys.
•Strike-Slip faults- (Shear force) rocks on either side are moving pass each other. Transform Plate Boundaries are present along these faults. San Andreas fault is form.
Forces in Earth’s Crust
(Page 44-45)
•Tension, compression, and shearing are different kinds of stresses and over millions of years they have changed the shape and volume of the rocks.
•Rocks are constantly under going a lot of stress through stretching and bending.
•Tension - stretches rock ( 2 plates are moving apart) forms a valley
•Compression – pushing rocks together ( 2 plates are moving toward each other) forms a hill
•Shearing – causes masses of rock to slip (2 plates that move pass each other in opposite directions)
(Page 46-47)
When a weak point is present it will create a break within the rock. The rock will then move and a fault will appear. These faults form along plate boundaries. There are 3 types of faults; Normal, Reverse, and strike-slip
•Normal faults- subject to tension. Tension will pull rocks apart. This fault is at an angle so one block of rock lies above the fault (Footwall) and the other block lies below ( Hanging Wall) (Divergent Plate Boundaries) (Rift Valleys) ( Great Basins) Two parallel normal faults will form folded mountains.
•Reverse faults- subject to compression. Compression pushes on rocks from opposite directions. This fault has one side of a reverse fault which lies at an angle above the other side. Unlike the normal fault the hanging wall is higher than the footwall. The faults are form at the Convergent Plate Boundaries. These faults form Mountain ranges. These faults create folds in the earth’s crust. They will form upward arches (Anticlines) ridges and downward arches (Synclines) valleys.
•Strike-Slip faults- (Shear force) rocks on either side are moving pass each other. Transform Plate Boundaries are present along these faults. San Andreas fault is form.