Plate tectonics

by: Samuel Gonzales

Three Layers And Why Their Important

The 3 types of layers of earth is the crust the mantel and the core. (Insert why earth layers are important here)

Continental Drift And Who Created The Hypothesis.

continental drift is the gradual movement of the continents across the earth's surface through geological time. This is the definition of continental drift. Continental drift is the theory of why earth's continents drift on earth surface. The hypothesis that continents 'drift' was first put forward by Abraham Ortelius in 1596 and was fully developed by Alfred Wegener in 1912 when he noticed that the shapes of continents on either side of the Atlantic Ocean seem to fit together this is what I found on this topic Africa and south America have had this problem.

evidence for continental drift

Wegener noticed that the continents seemed to fit together, not at the continuously changing shoreline, but at the edge to their continental shelves. He derived this hypothesis from the observation that the continents in the southern hemisphere exhibit an identical pattern of rock and fossils known as the "Gondwana sequence". The most logical explanation was that the continents themselves were once parts of a much larger "super-continent" which was named Pangaea.

A second idea supporting movement of the continents was the glacial till deposits in the southern hemisphere. With the continents in their present positions, the till deposits indicate erratic glacier motion. When the continents are fitted together, they show a much more streamlined motion of the glacier from southern Africa and Northern Australia outward.

sea floor spreading

A process that occurs at mid ocean ridges where new oceanic crust is formed

who discovered sea floor spreading

Harry Hess discovers sea floor spreading

sea floor spreading helps scientists to prove continental drift

In 1965, a Canadian geophysicist, J. Tuzo Wilson, combined the continental drift and seafloor spreading hypotheses to propose the theory of plate tectonics. Tuzo said that Earth's crust, or lithosphere, was divided into large, rigid pieces called plates.