Evidence For Ocean Floor Spreading

The continents bordering the atlantic ocean for example are believed to be moving away from the mid atlantic ridge at a rate of 1 2 cm 0 4 0 8 inch per year thus increasing.

Evidence for ocean floor spreading.

First samples of the deep ocean floor show that basaltic oceanic crust and overlying sediment become progressively younger as the mid ocean ridge is approached and the sediment cover is thinner near the ridge. Spreading rate is the rate at which an ocean basin widens due to seafloor spreading. The rate at which new oceanic lithosphere is added to each tectonic plate on either side of a mid ocean ridge is the spreading half rate and is equal to half of the spreading rate. Variations in the intensity and polarity of earth s magnetic field are considered to be recorded in the remanent magnetism of the igneous rocks as they solidified and cooled through the curie temperature at the crest of an oceanic ridge and subsequently.

Subduction and sea floor spreading are processes that could alter the size and form of the ocean. These age data also allow the rate of seafloor spreading to be determined and they show that rates. For instance the atlantic ocean is believed to be expanding because of its few trenches. Spreading rates determine if the ridge is fast intermediate or slow.

Basalt the once molten rock that makes up most new oceanic crust is a fairly magnetic substance and scientists began using magnetometers to measure the magnetism of the ocean floor in the 1950s what they discovered was that the magnetism of the ocean floor around. This spreading creates a successively younger ocean floor and the flow of material is thought to bring about the migration or drifting apart of the continents. Several types of evidence supported hess s theory of sea floor spreading. It is suggested that the entire history of the ocean basins in terms of oceanfloor spreading is contained frozen in the oceanic crust.

This evidence led scientists to look again at wegener s hypothesis of continental drift. Eruptions of molten material magnetic stripes in the rock of the ocean floor and the ages of the rocks themselves. The magnetism of mid ocean ridges helped scientists first identify the process of seafloor spreading in the early 20th century. As upwelling of magma continues the plates continue to diverge a process known as seafloor spreading 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.