Seafloor Spreading Theory Year

Sea floor spreading theory.

Seafloor spreading theory year.

At spreading rates of about 15 cm 6 inches per year the. To understand the concept of seafloor spreading we must first understand some basic concepts that form the cornerstones for the concept of seafloor spreading. Seafloor spreading rates are much more rapid in the pacific ocean than in the atlantic and indian oceans. Evidence of sea floor spreading.

Seafloor spreading proves that the ocean itself is a site of tectonic activity. Every so often it has occurred over 170 times over the past 100 million years the poles will suddenly switch. 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. Supporters of continental drift originally theorized that the continents moved drifted through unmoving oceans.

Seafloor spreading helps to explain continental drift in the theory of plate tectonics. Seafloor spreading disproves an early part of the theory of continental drift. Convection current theory convection current theory is the soul of seafloor spreading theory. That is it explains why the age thickness and density of the oceanic crust increases with distance from the mid oceanic ridge.

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. 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. When oceanic plates diverge tensional stress causes fractures to occur in the lithosphere. The ocean plates spread and grow in opposite directions so rocks that are equidistance from the center have the same magnetic polarity and age.

Arthur holmes in 1930s discussed the possibility of convection currents. This evidence was from the investigations of the molten material seafloor drilling radiometric age dating and fossil ages and the magnetic stripes. The mid ocean ridge curves like the seams of a baseball along the sea floor extending into all of earth s oceans. 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.

Sea floor spreading powerpoint 1. 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. Most of the mountains in the mid ocean ridge lie hidden under hundreds of meters of. The motivating force for seafloor spreading ridges is tectonic plate slab pull at subduction zones rather than magma pressure although there is typically.

These cornerstones are convectional current theory and paleomagnetism. As the magma and lava cool at seafloor spreading centers whatever magnetic field is present get ingrained into the rock.