Deep Sea Floor Spreading

As upwelling of magma continues the plates continue to diverge a process known as seafloor spreading.

Deep sea floor spreading.

Radiometric dating of a magnetic anomaly stripe of rock that is 225 km away from the mid ocean ridge axis gives an age of 4 5 million years. The mid atlantic ridge for instance separates the north american plate from the eurasian plate and the south american plate from the african plate. The mid ocean ridge is where the seafloor spreading occurs in which tectonic plates large slabs of earth s lithosphere split apart from each other. 20 000 cm per year.

Seafloor spreading helps to explain continental drift in the theory of plate tectonics. Seafloor spreading is a geologic process where there is a gradual addition of new oceanic crust in the ocean floor through a volcanic activity while moving the older rocks away from the mid oceanic ridge. On the basis of tharp s efforts and other new discoveries about the deep ocean floor hess postulated that molten material from earth s mantle continuously wells up along the crests of the mid ocean ridges that wind for nearly 80 000 km 50 000 miles through all the world s oceans. Seafloor spreading occurs along mid ocean ridges large mountain ranges rising from the ocean floor.

The volcanoes of hawaii are located above a deep mantle hot spot. The seafloor spreading hypothesis was proposed by the american geophysicist harry h. Assuming a constant rate seafloor spreading in this area occurs at a rate of choose one. These age data also allow the rate of seafloor spreading to be determined and they show that rates vary from about 0 1 cm 0 04 inch per year to 17 cm 6 7 inches per year.

If the oceanic crust reaches a deep sea trench it sinks into the trench and is lost into the mantle. The motivating force for seafloor spreading ridges is tectonic plate slab pull at subduction zones rather than magma pressure although there is typically significant magma activity at spreading ridges. 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 east pacific rise is a mid ocean ridge that runs through the eastern pacific ocean and separates the pacific plate from the north american plate the cocos plate the nazca plate and the antarctic plate.

Scaling the tallest mountain on earth would take you not to mt. First you will need to get into a deep ocean submersible and dive almost 4 miles under the surface of the pacific ocean to the sea floor. Everest but to mauna kea on the big island of hawaii. When oceanic plates diverge tensional stress causes fractures to occur in the lithosphere.

Scientists now know that the oldest crust is coldest and lies deepest in the ocean because it is less buoyant than the hot new crust seafloor spreading is the mechanism for wegener s drifting continents. They re not part of the east pacific oceanic ridge. 5 cm per year. First related the symmetrical magnetic patterns in seafloor basalts to sea floor spreading at a mid ocean ridge.