Sea floor spreading

The slit is your mid-ocean ridge, the place where the plates are moving away from each other.

Sea floor spreading

Related to Seafloor Spreading Theory: First proposed in the early s by the American geologist Harry H. Though first proposed by American geologist Frank Bursley Taylor in a lecture inthe first detailed theory of Click the link for more information. Discovery of the Mid-Ocean Ridges Development of highly sophisticated seismic recorders and precision depth recorders in the s led to the discovery in the early s that the Mid-Atlantic Ridge, a vast, sinuous undersea mountain chain bisecting the Atlantic Ocean, was in fact only a small segment of a globe-girdling undersea mountain system some 40, mi 64, km in length.

Sea floor spreading

In many locations, this mid-ocean ridge was found to contain a gigantic cleft, or Sea floor spreading, 20 to 30 mi 32—48 km wide and c.

The ridge itself does not form a smooth path, but is instead offset in many places. Faults on other planets and satellites of the solar system also have been recognized. The ridge crest and its associated transform faults are the locus of nearly all shallow earthquakes occurring in mid-ocean areas.

Continued study of the mid-ocean ridges is a major component of U. Role of the Spreading Center In Hess proposed that the seafloor was created at mid-ocean ridges, spreading in both directions from the ridge system.

When the magma hardens, it forms new oceanic crust that becomes welded to the original crust. Spreading is believed to be caused by far-field stresses, and the upwelling of the mantle beneath the spreading axis is the passive response to plate separation.

The oceanic trenches bordering the continents mark regions where the oldest oceanic crust is reabsorbed into the mantle through steeply inclined, earthquake-prone subduction zones. The pull of the deeply plunging lithosphere is one of the forces that may drive plate separation.

Supporting Evidence for Seafloor Spreading Abundant evidence supports the major contentions of the seafloor-spreading theory. 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.

Second, the rock making up the ocean floor is considerably younger than the continents, with no samples found over million years old, as contrasted with maximum ages of over 3 billion years for the continental rocks.

This confirms that older ocean crust has been reabsorbed in ocean trench systems. A timescale for "normal" and "reversed" polarity was established, showing magnetic "flip-flops" in the past 76 million years. Magnetic surveys conducted near the mid-ocean ridge showed elongated patterns of normal and reversed polarity of the ocean floor in bands paralleling the rift and symmetrically distributed as mirror images on either side of it.

The magnetic history of the earth is thus recorded in the spreading ocean floors as in a very slow magnetic tape recording, forming a continuous record of the movement of the ocean floors. Other supportive evidence has emerged from study of the fracture zones that offset the sections of the ridge.

Want to thank TFD for its existence? Link to this page:This series shows the physical processes and human activities that shape our planet. From earthquakes and volcanoes to the creation of sea-floor crusts and shifting river courses, Earth Revealed offers stunning visuals that explain plate tectonics and other geologic concepts and principles.

Sea floor spreading

Follow geologists in the field as they explore the primal forces of the Earth. sea-floor spreading The theory that the ocean floor is created at the spreading (accretionary) plate margins within the ocean basins.

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Igneous rocks rise along conduits from the mantle, giving rise to volcanic activity in a . (Read the explanation below, while you wait for the animation to load.) This animation shows the breakup of Pangea and the pattern of seafloor spreading that created the Atlantic, Indian and Pacific Oceans during the last million years.

Plate Tectonics: The Rocky History of an Idea. Close examination of a globe often results in the observation that most of the continents seem to fit together like a puzzle: the west African coastline seems to snuggle nicely into the east coast of South America and the Caribbean sea; and a similar fit appears across the Pacific.

the ground that is at the bottom of the sea. See the full definition for seafloor in the English Language Learners Dictionary. Rift zones are divergent plate boundaries. Most of them occur along the seafloor as mid-ocean ridges. Where two plates are moving away from each other, molten rock rises to .

Plate Tectonics