Hess Sea Floor Spreading

What evidence supports hess s theory of seafloor spreading.

Hess sea floor spreading. As a general rule fast ridges have spreading opening rates of more than 90 mm year. Spreading rate is the rate at which an ocean basin widens due to seafloor spreading. He also found out that the temperature near to the mid atlantic ridge was warmer than the surface away from it.

This theory later became known as sea floor spreading. Check all that apply. In this classic paper hess outlined the basics of how seafloor spreading works.

Hess also provided an explanation for the apparent contradiction that the ocean floor was 4 million years old but there was almost no sediment deposited on it. In addition he found that the deepest parts of the oceans were very close to continental margins in the pacific with ocean trenches extending down to depths of over 11 km in the case of the marianas trench off the coast of japan. Hess s model was later dubbed seafloor spreading by the american oceanographer robert s.

The age of different rocks on earth s surface e. Pillow shaped rocks found in the sea. By the use of the sonar hess was able to map the ocean floor and discovered the mid atlantic ridge mid ocean ridge.

Hess proposes sea floor spreading 1960. Seafloor spreading theory that oceanic crust forms along submarine mountain zones known collectively as the mid ocean ridge system and spreads out laterally away from them. This seafloor spreading hypothesis had been proposed a few years earlier by harry hess a petrologist at princeton university and robert dietz an oceanographer in the us coast and geodetic survey the federal department that made maps of the oceans and us coastlines.

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. Hess discovered that the oceans were shallower in the middle and identified the presence of mid ocean ridges raised above the surrounding generally flat sea floor abyssal plain by as much as 1 5 km. Molten rock magma oozes up from the earth s interior along the mid oceanic ridges creating new seafloor that spreads away from the active ridge crest and eventually sinks into the deep oceanic trenches.