The Evidences of the Seafloor Spreading:-
The hypothesis of the seafloor spreading propounded by Hary Hess had stated numerous evidences that supported seafloor spreading and the Continental drift theory also. The evidence were based on the fossils age,volcanic rocks,the seafloor drill,molten magma,and the magnetic field.
The fossils age:-
The hot molten lava spreads along the ridge and forms a new oceanic crust.The old crust pushed by the new crust toward the coast or trench. The fossils found near oceanic ridge is younger than away from the ridge.
The age of Volcanic rocks:-
It is found that volcanic rocks near the ridge is younger than any other rocks along the ridges. It is proved that the age of Continental crust is 3million years whereas the ocean crust formed more than 200million years.
Molten Material:-
Hary Hess discovered that the temperature near the mid Atlantic ridge is warm.So he started to survey on the ocean floor. During the survey ,he observed that molten magma upwelling continuously.he also stated that the conventional current in asthenosphere pushed the magma upward . This thermal convection current formed due to the Radioactive energy from the centre of the earth.Continues upwelling of magma makes the temperature high at the ridge.
Seafloor Drill:-
Using the seafloor drill system helps to collect evidence about the seafloor spreading. This system reveals that the rocks which upwelling become more younger than the rocks away from the ridge. The old rocks are relatively denser and thicker. The hot molten upwelling magma push the rock away from the ridge
Magnetic strip:-
W.G. Vine and Matthew surveyed on magnetic field on the central part of carlsberg ridge in Indian ocean in 1963.Both stated that there are temporal reversal of geomagnetic field. There are found normal and magnetic anomalies in alternative manner. After cooling and solidifying of magma,they get magnetized.during the normal geomagnetic field and reverse geomagnetic field, the rock belts get magnetized positive and negative respectively.
