[Type the company name] | Written Assignment 3 | Earth Science | | | |

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Written Assignment 3 1. Describe the bathymetry of the ocean seafloor and how the features relate to plate tectonics.
The term “bathymetry” originally referred to the ocean’s depth relative to sea level, although it has come to mean “submarine topography,” or the depths and shapes of underwater terrain. In the same way that topographic maps represent the three-dimensional features of overland terrain, bathymetric maps illustrate the land that lies underwater. The ocean has mountain ranges, volcanoes, trenches, canyons, and other structures.
The oldest rocks on the ocean floor are 180 million years old. This is young compared with the oldest continental rocks, which date from 3.8 billion years ago. While the continental crust has been steadily accumulating throughout Earth’s history, it seems the oceanic crust is created and destroyed rather quickly. It is created at the mid-ocean ridges from hot material rising in the mantle, and then spreads away from the ridges, before eventually being recycled into the mantle at subduction zones. Continental crust is always less dense and more buoyant than oceanic crust, so where they meet, it is the oceanic crust that gives way, sinking (subducting) back into the mantle
The boundaries of a tectonic plate may be divergent, convergent, or transform. At divergent boundaries, the crust is extended, thinned, and fractured by the upwelling of hot mantle material. The crust buoys up, producing a mid-ocean ridge, and lava is extruded through a central rift valley to create new oceanic crust. Seamount volcanoes may also arise.
Tectonic plates collide at convergent boundaries. Where oceanic crust meets continental crust, the latter may be compressed and thickened, resulting in mountain-building. The dense oceanic plate sinks