The movement of the Earth’s lithospheric plates which forms the Earth’s outer shell.
While you might not know it, Earth’s surfaces are constantly changing. Alfred Wegener, a man over 100 years old, proposed a theory called continental drift. His hypothesis claimed that all continents once became one supercontinent, called Pangaea. His hypothesis was initially dismissed by most people. It was a coincidence that South America, Africa and Asia seemed to be logically connected. However, fossils from the same type dinosaur were discovered on both continents many years later. Scientists believed Wegener was right. Scientists believe Wegener may have been right. Millions of years ago, continents were placed differently to how they are now. Plate tectonics explains that Earth’s crust is and upper mantle is separated into sections known as tectonicplates. The asthenosphere is the plastic-like layer in Earth’s mantle, and there are approximately 13 tectonic plate that float on it. These tectonic plates are slow to move, at a rate of 3 centimeters a year. That’s about the rate at which fingernails can grow. Plate boundary refers to the point where two or three plates meet. There are three types: convergent and divergent. These boundaries influence the surface of Earth and its changes.
Convergent boundaries arise when two plates of tectonic activity move toward each other. Mountain ranges are formed when both the continental (made from land) tectonic and tectonic plates collide. The collision of the Indian-continental plates and the Eurasian plates created the Himalaya mountain range. The highest mountain range in the world is found here! Mountain ranges, volcanoes, trenches form when oceanic and continental plates collide. Subduction occurs at these boundaries. Subduction is the process where an oceanic, or continental, plate collides with another plate. The oceanic is then pushed to the bottom of the continental plate. This happens because of the difference in density between oceanic and continental crusts. The oceanic crust sinks into earth because it is denser then continental crust. On top, the continental crust. This is how Andes Mountains came about. Many results can be expected when two oceanic plate collide. This is where subduction occurs, as well as trenches and volcanoes. An island arc is a group of islands that are shaped like an arch. They form when two oceanic plates collide. The denser plate sinks beneath the lighter one. Subducting plates can melt due to extreme heat from the mantle. This causes undersea volcanic eruptions. These volcanoes eventually erupt and grow until they reach their surface. Island arcs were responsible for the formation of the Caribbean Islands and Alaska’s Aleutian Islands. The Marianas Trench lies off Guam, in the West Pacific. It is seven-miles deep at its deepest, making it the lowest point on Earth. This trench was formed in the oceanic plates colliding. One of the plates was forced beneath and both plates ended-up going down. Another type of boundary is the divergent boundary. This occurs when two plates on the tectonic plate are moving away from one another. These plates can either be oceanic or continental. Seafloor spreading occurs when two oceanic plates move away from one another. According to Harry Hess, seafloor spreading occurs when magma, which is hotter and denser material, is pushed upwards towards Earth’s surface at the mid-ocean Ridge. Mid-Atlantic Ridge could be an example for a mid-ocean Ridge. New seafloor is being built here. However, the Marianas Trench, an older seafloor, is being destroyed by ocean trenches. As seafloor spreading continues, the Atlantic Ocean becomes larger and more extensive. The Pacific Ocean, however, is shrinking as a result of subduction at Ocean Trenches. Rift valleys form when two continental plates are separated. Rifts are valleys that result from two continent plates breaking apart. The Great Rift Valley is East Africa’s largest and most famous rift valley. Submarine, oceanic plates are separating from ocean trenches. Continental plates, however, are forming rift valleys.
A transform boundary is the third type of boundary. Transform borders are those where two tectonic rocks are either moving in opposite directions, or are sliding past eachother. Many earthquakes can be seen at these boundaries. The Ring of Fire also includes the San Andreas Fault, which can be found in Southern California. Many earthquakes occur in the Ring of Fire. It is found on the west coast of South America and North America.
Plate tectonics can be described as a complicated theory. The Earth’s surface will shift around because of the three types of boundary: transform, divergent and convergent. Earth’s ever-changing surfaces are responsible for many landforms such as subduction and trenches. Natural disasters can be caused by Earth’s tectonic plates. Scientists can’t always predict the timing of these natural disasters, but they know how best to prepare. Evidence has shown the Earth’s surface has been changing over many millions of years. The future will see it change again, which could have a devastating impact on the lives and livelihoods of those who live there.
