The Crust Under The Ocean Floor

Structure of the earth.

The crust under the ocean floor.

The continental crust covers only one third of the earth s surface and makes up all of the dry land found on earth. Oceanic crust the outermost layer of earth s lithosphere that is found under the oceans and formed at spreading centres on oceanic ridges which occur at divergent plate boundaries. As upwelling of magma continues the plates continue to diverge a process known as seafloor spreading. Continental crust earth.

The seafloor of the ionian sea is about 270 million years old. Oceanic crust is thin and young no more than about 20 km thick and no older than about 180 million years. It is light and brittle and can break. The destruction of oceanic crust occurs at subduction zones where oceanic crust is forced under either continental crust or oceanic crust.

The crust under land is thicker and contains more rock types. Subduction zone the place where one plate is getting bent and pulled under the edge of another plate. Everything older has been pulled underneath the continents by subduction. Plate tectonics plate tectonics seafloor spreading.

Oceanic crust covers about 60 percent of the earth s surface. These age data also allow the rate of seafloor spreading to be. New rock is formed by magma at the mid ocean ridges and the ocean floor spreads out from this point. The crust thickness averages about 18 miles 30 kilometers under the continents but is only about 3 miles 5 kilometers under the oceans.

Oceanic crust is born at the mid ocean ridges where plates are pulled apart. Samples collected from the ocean floor show that the age of oceanic crust increases with distance from the spreading centre important evidence in favour of this process. Oceanic crust is about 6 km 4 miles thick. The oceanic crust displays a pattern of magnetic lines parallel to the ocean ridges frozen in the basalt.

The oldest existing oceanic crust is in the ionian sea part of the eastern mediterranean basin. Largely due to subduction oceanic crust is much much younger than continental crust. A symmetrical pattern of positive and negative magnetic lines emanates from the mid ocean ridge. Today the atlantic basin is actively spreading at the mid atlantic ridge.

It is composed of several layers not including the overlying sediment. Two types of crust make up the land on earth and its ocean floor. Only a small portion of the oceanic crust produced in the atlantic is subducted.