The Crust Under The Ocean Floor

Two types of crust make up the land on earth and its ocean floor.

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. Everything older has been pulled underneath the continents by subduction. The seafloor of the ionian sea is about 270 million years old. Continental crust earth.

A symmetrical pattern of positive and negative magnetic lines emanates from the mid ocean ridge. Largely due to subduction oceanic crust is much much younger than continental crust. Oceanic crust is born at the mid ocean ridges where plates are pulled apart. The oldest parts of continental crust on the other hand are more than 4 billion years old.

The destruction of oceanic crust occurs at subduction zones where oceanic crust is forced under either continental crust or oceanic crust. Subduction zone the place where one plate is getting bent and pulled under the edge of another plate. The crust under land is thicker and contains more rock types. The oldest existing oceanic crust is in the ionian sea part of the eastern mediterranean basin.

These age data also allow the rate of seafloor spreading to be. The crust thickness averages about 18 miles 30 kilometers under the continents but is only about 3 miles 5 kilometers under the oceans. The process that forms new ocean floor and oceanic crust. 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.

New rock is formed by magma at the mid ocean ridges and the ocean floor spreads out from this point. The oceanic crust displays a pattern of magnetic lines parallel to the ocean ridges frozen in the basalt. Oceanic crust is thin and young no more than about 20 km thick and no older than about 180 million years. Plate tectonics plate tectonics seafloor spreading.

It is light and brittle and can break. It is composed of several layers not including the overlying sediment. As upwelling of magma continues the plates continue to diverge a process known as seafloor spreading. Today the atlantic basin is actively spreading at the mid atlantic ridge.

Only a small portion of the oceanic crust produced in the atlantic is subducted. Structure of the earth. 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.