Evidence For Ocean Floor Spreading

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.

Evidence for ocean floor spreading.

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. 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. These age data also allow the rate of seafloor spreading to be determined and they show that rates. It is suggested that the entire history of the ocean basins in terms of oceanfloor spreading is contained frozen in the oceanic crust.

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. For instance the atlantic ocean is believed to be expanding because of its few trenches. Due to this continuous seafloor spreading occurs and makes atlantic ocean floor to be connected to other continental crust making the ocean gets wider over the time. The magnetism of mid ocean ridges helped scientists first identify the process of seafloor spreading in the early 20th century.

Abundant evidence supports the major contentions of the seafloor spreading theory. This evidence led scientists to look again at wegener s hypothesis of continental drift. 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. Several types of evidence supported hess s theory of sea floor spreading.

Eruptions of molten material magnetic stripes in the rock of the ocean floor and the ages of the rocks themselves. Spreading rate is the rate at which an ocean basin widens due to seafloor 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. Spreading rates determine if the ridge is fast intermediate or slow.