Seafloor Spreading Theory Year

Arthur holmes in 1930s discussed the possibility of convection currents.

Seafloor spreading theory year. 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. The ocean plates spread and grow in opposite directions so rocks that are equidistance from the center have the same magnetic polarity and age. This evidence was from the investigations of the molten material seafloor drilling radiometric age dating and fossil ages and the magnetic stripes. Evidence of sea floor spreading.

At spreading rates of about 15 cm 6 inches per year the. Supporters of continental drift originally theorized that the continents moved drifted through unmoving oceans. This idea played a pivotal role in the development of the theory of plate tectonics which revolutionized geologic thought during the last quarter of the 20th century. Harry hess s hypothesis about seafloor spreading had collected several pieces of evidence to support the theory.

Seafloor spreading helps to explain continental drift in the theory of plate tectonics. Seafloor spreading proves that the ocean itself is a site of tectonic activity. As the magma and lava cool at seafloor spreading centers whatever magnetic field is present get ingrained into the rock. Every so often it has occurred over 170 times over the past 100 million years the poles will suddenly switch.

The theory of sea floor spreading states that new oceanic crust is being formed continuously at mid oceanic ridges while the older rocks move away from the ridge. That is it explains why the age thickness and density of the oceanic crust increases with distance from the mid oceanic ridge. When oceanic plates diverge tensional stress causes fractures to occur in the lithosphere. Convection current theory convection current theory is the soul of seafloor spreading theory.

Sea floor spreading powerpoint 1. Most of the mountains in the mid ocean ridge lie hidden under hundreds of meters of. As per seafloor spreading theory the mid oceanic ridge is the region where at the crest of oceanic ridges through the rupture of the oceanic crust and the crack continuous new lava eruption thrusts into it consequently pushing the oceanic crust on either side. Mapping the mid ocean ridge the east pacific rise is just one part of the mid ocean ridge the longest chain of mountains in the world.

It leads to the formation of new material on the ridge. These age data also allow the rate of seafloor spreading to be determined and they show that rates vary from about 0 1 cm 0 04 inch per year to 17 cm 6 7 inches per year. Seafloor spreading rates are much more rapid in the pacific ocean than in the atlantic and indian oceans. To understand the concept of seafloor spreading we must first understand some basic concepts that form the cornerstones for the concept of seafloor spreading.

These cornerstones are convectional current theory and paleomagnetism. The motivating force for seafloor spreading ridges is tectonic plate slab pull at subduction zones rather than magma pressure although there is typically.