The Theory of Continental

Introduction

The theory of continental drift was championed by Alfred Wegener in through the first few decades in the twentieth century ("Wegener, Galileo and,"). The theory of continental drift says that all of the continents were at once joined together, but over time they have drifted apart. During the early part of the twentieth century scientists disagreed with this theory and challenged, but over time in the later part of the twentieth century this theory has become more accepted (repurposed from DB4).

Alfred Wegener

Alfred Wegener was born in Berlin, which is also where he went to school and earned his doctorate degree in astronomy. His theory of Continental Drift was thought of in the early 1900's when he noticed that the continents appeared as if they would fit together like a jigsaw puzzle. This intrigued his curiosity which in turn caused him to do more research on the idea of continental drift, until his death in 1930 on his third expedition to Greenland ("Alfred Wegener,").

Acceptance of His Theory

While Alfred Wegener is considered to be the pioneer of continental drift, his theory was not very well accepted during his time. Many scientists disapproved of Wegener's theory for many different reasons. Scientists would argue that his statements were vulnerable and not plausible. They would question his expertise on the subject since he was trained and held a degree in meteorology which had nothing to do with geology in their eyes. Out of all of the reasons that scientists rejected the idea of continental drift the one that seemed to stick the most was that this theory lacked a mechanism which is often taught in colleges today (Mansur, 2010).

The theory of continental drift was not accepted until 30 years after the untimely death of Alfred Wegener in the 1960's. This is when scientists began to question and talk about the theory again. This came about when Jack Oliver, Bryan Isacks and Lynn Sykes coined the term global tectonics. As of today the continental drift theory is widely accepted across the entire globe on all continents mostly because tectonics provides a mechanism which supports Wegener's theory.

Geographical Evidence

One of the earliest of Wegener's theory was that all of the continents fit together like a puzzle. As you can see on a map of the globe today we can definitely see where continents used to fit together, especially with Africa and The America's being the most prevalent. Other geographical evidence would consist of things like fossils of specific species from the same time period being found on different continents like Africa and the America's. These different types of fossils would include things like animals as well as plants. Along with the fossil evidence there were also evidence of soil or rock that were found on these different continents which all could lead one to believe that they were all joined together at one time as one giant super-continent which Wegener called Pangaea ("Bugielski,").

Glacier till deposits in the southern hemisphere would also provide evidence to support the continental drift theory. When the jigsaw puzzle is all pieced together there were deposits that would have been centrally located from Southern Africa into Australia. With this said if these glaciers were located in these areas with the continents in their current positions the majority of the world would have been under ice and we know that is was not ("Bugielski,).

Paleomagnetism is when lava rises to the surface and cools and as a result the magma becomes magnetized. This supports continental drift because different magma or metals that have been magnetized from different parts of the world were in an area they were not supposed to, be according to their magnetic alignment with the poles ("Bugielski,).

Plate Tectonics

Plate tectonics is the kicker of them all which really supported the theory of continental drift. Plate tectonics is a theory in which the earth has an outer layer and that layer is made up of many plates. These plates have been shifting and moving throughout time and they are the reason for different things like mountains, earthquakes and volcanoes. Over millions of years these plates have moved and shifted which, has overtime cause what was once one giant land mass to separate into the continents as we know them today ("Intro to plate,"). Plate tectonics proves Wegeners theory of continental drift by providing a mechanism which would be able to move land masses over a long period of time.

The way all of this works is that the earth's crust which is made up of these plates is sitting above another layer of earth that is called the mantle. In the mantle you have what are called convection currents. Convection currents are heat from the outer core which transfers to the mantle rock causing the mantle rock to become less dense then it already is. This mantle rock then rises towards the earth's crust then cools as it gets closer to the crust. When the mantle rock cools it becomes denser than it previously was and travels back toward the core. This movement beneath the crust is what causes the crust or plate to shift. Think of a pot of pinto beans boiling in water. If you let the beans sit