What theory explains the formation and movement of the outer surface of the Earth?
1 Answer
Explanation:
The theory of plate tectonics postulates that the earth's crust is main of large plates of crust that move across the surface of the earth. The outermost portion of the earth, the lithosphere, is broken into multiple plates (seven large ones and many smaller ones) that move very slowly in relation to one another.
The theory hypothesis is that convection currents in the mantle cause upward movement of hot magma at breaks in the crust. These places cause magma to move upwards and outwards creating new crust. The MidAtlantic ridge is one of these places.
The MidAtlantic ridge is a divergent boundary. Crust moves outward from the ridge in both direction ( East and West.) The crust moving West adds to the North American plate and the crust moving East adds to the European plate.
Where the Pacific Ocean plate meets the South American plate there is a subduction zone. The Pacific Ocean plate is forced under the Continental plate causing the the rocks and sediments in the Ocean Plate to melt as they are crushed and heated as they are push under closer to the mantle.
Subduction zones result in the formation of volcanos and mountains like the Andes.
The theory of plate tectonics was first proposed as the Theory of Continental Drift. The theory was rejected until late in the 1970's and early 1980's. Today the evidence for the movement of the plates is so strong that the theory is generally accepted.
Part of the resistance to the acceptance of the theory was that the Theory appeared to contradict the current understanding of how the fossil sedimentary layers of the earth's crust were formed and the dating of fossils.
