![]() At this point, water from the ocean will rush in, forming a new sea or ocean basin in the rift zone. Eventually, the widening crust along the boundary may become thin enough that a piece of the continent breaks off, forming a new tectonic plate. Early in the rift formation, streams and rivers flow into the low valleys and long, narrow lakes can be created. As the crust widens and thins, valleys form in and around the area, as do volcanoes, which may become increasingly active. This rift is a dropped zone where the plates are pulling apart. When two continental plates diverge, a valleylike rift develops. The magma also spreads outward, forming new ocean floor and new oceanic crust. Magma then oozes up from the mantle to fill in the space between the plates, forming a raised ridge called a mid-ocean ridge. As plates made of oceanic crust pull apart, a crack in the ocean floor appears. But if these huge masses of crust are moving apart, what happens in the space left between them?ĭivergent boundaries in the middle of the ocean contribute to seafloor spreading. The San Andreas Fault is one of the best examples of lateral plate motion.Slip, Slide, & Collide Divergent Boundaries - Spreading PlatesĪt divergent boundaries, tectonic plates are moving away from each other. When two tectonic plates slide past each other, the place where they meet is a transform or lateral fault. This can lead to the formation of huge, high mountain ranges such as the Himalayas. Since neither plate is stronger than the other, they crumple and are pushed up. About 80% of earthquakes occur where plates are pushed together, called convergent boundaries.Īnother form of convergent boundary is a collision where two continental plates meet head-on. Sometimes the molten rock rises to the surface, through the continent, forming a line of volcanoes. The rocks pulled down under the continent begin to melt. Subduction causes deep ocean trenches to form, such as the one along the west coast of South America. When a continental plate meets an oceanic plate, the thinner, denser, and more flexible oceanic plate sinks beneath the thicker, more rigid continental plate. The Great Rift Valley in Africa, the Red Sea and the Gulf of Aden all formed as a result of divergent plate motion.Ĭonvergent (Colliding): This occurs when plates move towards each other and collide. The earthquakes that occur along these zones, called spreading centers, are relatively small. Molten rock from the mantle erupts along the opening, forming new crust. The three main types of plate movements include:ĭivergent (Spreading):This is where two plates move away from each other. The movements of the plates help shape the geological features of our planet. Other plates include continents, and some plates include both continents and ocean. Some of the plates have ocean water above them. When the plates finally give and slip due to the increased pressure, energy is released as seismic waves, causing the ground to shake. ![]() Most seismic activity occurs at three types of plate boundaries-divergent, convergent, and transform.Īs the plates move past each other, they sometimes get caught and pressure builds up. Movement in narrow zones along plate boundaries causes most earthquakes.
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