A Movement Of Thr Sea Floor Along Many Rifts

This graphic shows several ocean floor features on a scale from 0 35 000 feet below sea level.

A movement of thr sea floor along many rifts.

This evidence led early marine geologists to deduce that the mid ocean ridges were formed by seafloor volcanoes. The mid ocean ridge is the most extensive chain of mountains on earth stretching nearly 65 000 kilometers 40 390 miles and with more than 90 percent of the mountain range lying in the deep ocean. 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 east pacific rise is a mid ocean ridge that runs through the eastern pacific ocean and separates the pacific plate from the north american. In international geophysics 2000.

Continental drift large scale horizontal movement of continents relative to one another and to the ocean basins during one or more episodes of geologic time. Plates are composed of lithosphere about 100 km thick that float on the ductile asthenosphere. The red sea is an example of a new arm of the sea. The east african rift was thought to be a failed arm that was opening more slowly than the other two arms but in 2005 the ethiopian afar geophysical lithospheric experiment reported that in the afar region september 2005 a 60 km fissure opened as wide as eight meters.

Seafloor spreading occurs along mid ocean ridges large mountain ranges rising from the ocean floor. A mid ocean ridge mor is a seafloor mountain system formed by plate tectonics it typically has a depth of 2 600 meters 8 500 ft and rises about two kilometers above the deepest portion of an ocean basin this feature is where seafloor spreading takes place along a divergent plate boundary the rate of seafloor spreading determines the morphology of the crest of the mid ocean ridge and its. As the lithospheric plates move across earth s surface driven by forces as yet not fully understood they interact along their boundaries diverging converging or slipping past each other. At their crests they had v shaped central valleys with steep faults on either side.

The scientists also observed that the crest of the ridges had a topography that closely resembled volcanic rift zones on land. The massive mid ocean ridge system is a continuous range of underwater volcanoes that wraps around. Continental shelf 300 feet continental slope 300 10 000 feet abyssal plain 10 000 feet abyssal hill 3 000 feet up from the abyssal plain seamount 6 000 feet. The following features are shown at example depths to scale though each feature has a considerable range at which it may occur.

By combining the sea floor spreading theory with continental drift and information on global seismicity the new theory of plate tectonics became a coherent theory to explain crustal movements. This concept was an important precursor to the development of the theory of plate tectonics which incorporates it.