Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Provenance (geology) wikipedia , lookup
Post-glacial rebound wikipedia , lookup
Age of the Earth wikipedia , lookup
History of geology wikipedia , lookup
Great Lakes tectonic zone wikipedia , lookup
Composition of Mars wikipedia , lookup
Tectonic–climatic interaction wikipedia , lookup
Large igneous province wikipedia , lookup
Plate tectonics wikipedia , lookup
Geochemistry wikipedia , lookup
7.4 Forces that move plates. Focus Write a description of each example and suggest how each might have formed. Review Continental – Continental - Convergent Oceanic – Oceanic - Convergent Continental – Oceanic – Convergent Divergent Transform Deformation Deformation – the process by which the shape of a rock changes because of stress. Rock layers bend when stress is placed on them. If enough stress is applied the rocks will break. Compression Compression – the type of stress that occurs when an object is squeezed. Causes the formation of large mountains. Tension Tension – is stress that occurs when forces act to stretch an object. Occurs Ex. at divergent plate boundaries. Mid-ocean ridges. Shear A stress in which tension is usually created by sliding. Earthquakes are common due to these forces. Folding Folding – the bending of rock layers due to stress. We assume that all rock layers start out as horizontal layers. When you see a fold deformation must have occurred. Types of Folds Anticlines – upward-arching folds. Synclines – downward, trough like folds. Faulting Fault – a break in a body of rock along which one block slides relative to another. Fault blocks – the blocks of crust on each side of the fault. Faulting Hanging wall – a wall that you could not physically stand on. Faulting Footwall – the wall that you could walk on. Normal Faults Normal fault – When the fault moves, it causes the hanging wall to move down relative to the footwall. Occurs where there is tension that pulls rocks apart. Reverse Faults Reverse Fault – when it moves it causes the hanging wall to move up relative to the footwall. Happens together. when forces are compressed pushing rocks Strike Slip Faults Strike-slip Fault – form when opposing forces cause rock to break and move horizontally. Ex. San Andreas Output: Diagram Draw a diagram showing the three different types of faults and the stress that is used to create those faults boundaries. Folded Mountains Form at convergent boundaries when continents have collided. Rock layers are squeezed together and pushed upward. Ex. Appalachian Mountains Fault-Block Mountains Fault-Block Mountains – form when the tension causes large block of the Earth’s crust to drop down relative to other block. Normally have sharp jagged edges. Tetons in Wyoming Volcanic Mountains 1. 2. Form when: oceanic plates subduct below each other continental and oceanic plates subduct below each other. Some of the most famous volcanic mountains are located around the rim which has become known as the ring of fire. Ring of Fire Uplift and Subsidence Uplift – the rising of regions of Earth’s crust to higher elevations. Subsidence – the sinking of regions of the Earth’s crust to lower elevations. Uplifting of Depressed Rocks Rebound – the process of land rising without deformation. The crust of the Earth slowly springs back to its previous elevation. Occurs normally when weight is removed from the crust. Subsidence of Cooler Rocks Hot rocks take up more space than cooler rocks. Because of this, rocks near mid-ocean ridges tend to be higher up than those that are father away. As you move farther away from the mid-ocean ridge rocks tend to subside. Tectonic Letdown Rift-zone – a set of deep cracks that forms between two tectonic plates that are pulling away from each other. Pg 212.