Introduction to Mid-Ocean Ridges:
The National Oceanic and Atmospheric Admiration-NOAA, is a leader in exploring the geologic and biologic mysteries of the deep-sea. They began their voyage in the mid-ocean ridge. The mid-ocean ridge system contains massive volcanoes, violent earthquakes, and bizarre life forms hidden deep beneath the sea. The mid-ocean ridge system is 65,000 kilometers long and 1,500 km wide. It is located between continents. The type of plate boundary that forms a mid-ocean ridge system is divergent. Tectonic activities pull apart of the oceanic crust. This causes cracks along the linear rift zone. As the plate thins, and magma rises into the fracturing crust. Crust rises to form a high ridge on the sea floor because the rift zone becomes less dense and more buoyant as it thins down and heats up. Most of the ocean's crust is formed by rocks called basaltic dikes. The out skin of the flow of lava solidifies instantly while the interior remains molten and keeps moving. This inner turmoil distorts the surface of the basalt into irregular, lumpy pillows. The Juan De Fuca Ridge creates new crust every 100 years. The crust is broken and pushed apart by continued divergence and volcanism.
The rate of ridges vary from 1-3 cm per year to 10-20 cm per year. The rate of spreading influences the topography of the ridge. A slow spreading ridge displays a steep irregular topography and is relatively narrow. Seawater seeps into the oceanic crust and becomes extremely hot, as much as 400°C. Hydrothermal vents are formed when the earth's crust plates move apart, allowing cold sea water to seep down into the openings. The water will then heat up. Then part of it will be removed. Next, the fluid sinks and the deeper that it goes the hotter the fluid will get. Stuff from the crust will dissolve into the liquid. It will then rise and the fluid will then gush out of the ocean floor. This will create a chemical reaction.
Plate Tectonics
2,000 strong quakes and large eruptions occur ever year. Earthquakes form through a theory called the tectonics theory. The Tectonics Theory states that the surface of the earth is not fixed and eternal, but it is a in a constant, ever-changing motion. Plate tectonics explain how the world works. The tectonic forces originate deep within the planet. Within our planet, we have three layers; the central core, mantle, and outer crust. Tectonic activity is concentrated in the upper 700 kilometers of the planet, in the uppermost mantle and the crust. The Lithosphere encases the entire Earth. They are broken into plates that butt up against one another. The asthenosphere is a solid but soft layer of the upper mantle. It is important to plate tectonics because it can deform and flow so that heavy plates float on top of it. As it circulates, the plates above begin to move. Plates move extremely slow. It move about the same speed that fingernails grow. There are three types of boundaries that are caused by the movement of plates. The three types of plate boundaries are divergent, convergent, and transform. Divergent boundaries are plates that pull apart. Magma, molten rock, rises from the mantle. It oozes up into the gap and hardens into solid rock forming new crust on the torn edges of the plates. The oceanic crust is made out of basalt, created by the magma. During convergent boundaries, new crust is formed through rising magma. The magma then forms melting plates into granite. Granite is a light colored, low-density rock that makes up the continents. During transform boundaries, natural or manmade structures that cross the boundary are offset and they split into pieces and carried in opposite directions. It is important because theses plates alternately jam and jump against each other, earthquakes rattle through a wide boundary zone.