The Crust Under The Ocean Floor

Magma oozes up from the mantle through a crack in the ocean floor filling in the space between the plates and spreading out from the plate boundary.

The crust under the ocean floor. 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. It is light and brittle and can break. The oldest parts of continental crust on the other hand are more than 4 billion years old. 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 covers about 60 percent of the earth s surface. A symmetrical pattern of positive and negative magnetic lines emanates from the mid ocean ridge. Subduction zone the place where one plate is getting bent and pulled under the edge of another plate. Oceanic crust is born at the mid ocean ridges where plates are pulled apart.

Structure of the earth. These age data also allow the rate of seafloor spreading to be. The seafloor of the ionian sea is about 270 million years old. 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.

The continental crust covers only one third of the earth s surface and makes up all of the dry land found on earth. Only a small portion of the oceanic crust produced in the atlantic is subducted. Today the atlantic basin is actively spreading at the mid atlantic ridge. As upwelling of magma continues the plates continue to diverge a process known as seafloor spreading.

Two types of crust make up the land on earth and its ocean floor. Plate tectonics plate tectonics seafloor spreading. The process that forms new ocean floor and oceanic crust. Largely due to subduction oceanic crust is much much younger than continental crust.

The destruction of oceanic crust occurs at subduction zones where oceanic crust is forced under either continental crust or oceanic crust. Oceanic crust is about 6 km 4 miles thick. Continental crust earth. It is composed of several layers not including the overlying sediment.

The oldest existing oceanic crust is in the ionian sea part of the eastern mediterranean basin. The crust under land is thicker and contains more rock types. Oceanic crust is thin and young no more than about 20 km thick and no older than about 180 million years.