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The theory of plate techonics begins with the supercontinent Pangaea. "Everest is moving at a speed of 1/16 inch to 1/4 inch each year because India, which sits on a shifting plate, is being shoved under a plate that supports Nepal and China." The entire mountain range is moving toward China. Mount Everest is a great example of this theory. These moving plates can form new mountains and volcanoes, which can result in causing earthquakes ( earthquake information). Convection cells within the molten mantle could be the powerful force pushing these plates. Folded, tilted, faulted and displaced layers of rock also provide us with evidence of past crustal movements.
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These plates may collide, move apart or slide past one another. The moving plates move in different directions and at different speeds. The continents are made of lighter rocks that ride high on the moving plates. Plate tectonics combines the ides of sea floor spreading and continental drift. This led to the theory of plate tectonics. The Mid-Atlantic Ridge has older rocks at the outer surface while the newer rocks are at the center of the ridge. The theory of sea floor spreading is more proof of the moving continents. The plants and animals could not have traveled over such vast areas of ocean and survived unless the continents were joined at one point in time. Fossils records have proven similar animals and plants in many different places. If you look at the continents now it seems as if they are pieces of a jigsaw puzzle that can be put together.
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Through the years the continents slowly moved apart. The theory of continental drift explains how the continents were once together. S waves are secondary waves which travel in a rolling fashion and are slower than P waves. P waves are longitudinal while S waves are transverse. P waves are the primary waves that travel the fastest through the surface of earth. Earthquakes release two types of waves: P waves and S waves. The crust is in the form of a plate, which is floating on molten mantle. The build up of friction causes stress, which releases as sudden jerking, or an earthquake. Friction, the force opposing motion, prevents these plates from moving smoothly. The movement of the liquid portion of earths’ mantle may also be responsible for earthquakes, volcanic eruption and the formation of mountains and ocean basins.Įarthquakes are formed when sections of earth’s crust move past one another. The movement of the molten iron is believed to cause earths’ magnetic field. Due to the extreme pressure from the above layers the iron and nickel do not have the ability to expand or melt. Scientists’ suspect the inner core is solid iron and nickel. The rocks of the mantle can warp or change shape. The mantle consists of rocks heavier than that of the ocean crust. Continental crust is made up of assorted rocks, which are 20 times older than the rocks of the ocean floor. The oceanic crust is dark colored and heavier than continental crust. Continental crust and oceanic crust make up the thin layer on earth’s surface. By studying these earthquake waves a model was developed that showed Earth as having different layers. They sent vibrations into earth’s core and studied the changes in motion and speed as these vibrations moved into different mediums. Scientists could not just take earth and get an x-ray to see inside. The interior of earth has three parts: crust, mantle (upper and lower), and core (inner and outer). "Describe volcano and earthquake patterns, the rock cycle, and weather climate changes." The Physical Setting: Performance Indicator 2.2