Plate Tectonics Theory Gaining Credence

The theory of Plate Tectonics is a surprisingly recent discovery. The first driving force was in 1915 when Alfred Wegener published his book The Origin of Continents and Oceans. Wegener proposed the idea that the earth’s continent had once been a single super-continent, which he named Pangaea. Wegener explained how many things on earth were interconnected and Pangaea could be the solution for many scientific queries at the time. Many colleagues in the geologic field were skeptical of Wegener’s proposal because he couldn’t explain why the plates moved. It wasn’t until the 1960’s when enough data was collected on projects such as Bathymetry and the Phenomenon of Polar Wander, that a majority of scientists accepted Plate Tectonics.
The theory of Plate Tectonics is best described in layers. On top we have the least dense particles such as nitrogen and oxygen gas that make up our atmosphere. As we look deeper into the earth, data shows that denser elements and molecules are pulled into the center and less dense objects ejected due to mass. The core of our earth is made mostly of nickel and iron. The plates that move on the earth’s surface are dominantly solid objects that consist of our earth’s crust and the upper mantle. This is called the lithosphere. The upper part of the lithosphere, the crust, can be separated into two types, continental and oceanic. Continental crust is much thicker than the oceanic crust. This means the lithosphere has varying thicknesses across the planet. The lithosphere is divided into slowly moving plates moving in varying directions. Directly under the lithosphere is the asthenosphere. The asthenosphere consists of plastic rock, meaning it is a weak solid and has many of the same properties as liquid. The most important of these properties is that the asthenosphere can flow. Under the asthenosphere is a hotter and rigid mesosphere; its heat conducts to the flowing asthenosphere inducing convection, which is believed to be the one of the major driving forces in plate tectonics.
All plates move in relation to each other. They have boundaries where they can either converge, diverge, or transform. The geophysical effects of moving plates vary for oceanic and continental crust. Diverging oceanic plates result in mid-oceanic ridges. These mid-oceanic ridges are active chains of volcanoes that spew buoyant magma from underground to the surface; lava then cools creating new ocean crust. Over time the pressure of the rising magma moves the plates apart. This is called a Ridge Push force. Its opposing counterpart is the Slab Pull force. The Slab Pull force occurs when an oceanic-crusted plate boundary converges against continental or younger oceanic lithosphere. If the old oceanic lithosphere meets one of the boundaries, it will slide underneath. This subduction pushes the plate’s lithosphere down into the mantle. So it is easy to image these processes working together and acting like a huge planet-wide conveyor belt. Other sources of plate tectonic movement could be accredited to Heat Plumes. In this recent report by Science Daily, scientists describe how the location of a Heat plume between boundaries can alter the path of moving continents.
"There is a dramatic slow down in the northwards motion of the Indian plate around 50 million years ago that has long been attributed to the initial collision of India with the Eurasian plate," said Cande, a professor of marine geophysics in the Geosciences Research Division at Scripps. "An implication of our study is that the slow down might just reflect the waning of the mantle plume-the actual collision might have occurred a little later (Scripps Institution of Oceanography, University of California-San Diego, 2011)."
This research shows that the theory of plate tectonics is still underway. The next steps of adding research to this theory could be testing the implications of mantle plumes. The theory has come a long way in the past century since Wegener introduced it. With the work and new ideas coming out of institutions such as Scripps and the forward thinking of geologists in the field even more credence with be afforded the Theory of Plate Tectonics.

Bibliography
Marshak, S. (2008). Earth: Portrait of a Planet (4th ed.). New York: W.W. Norton.

Scripps Institution of Oceanography, University of California-San Diego. (2011, 07 06). New force driving Earth's tectonic plates. Retrieved 09 20, 2012 from Science Daily: http://www.sciencedaily.com/releases/2011/07/110706134139.htm