Earth Space Science
Plate Tectonics Theory
Plate tectonics is the theory that the outer rigid layer of the earth is divided into a couple of dozen plates that move around across the earth's surface relative to each other, like slabs of ice on a lake. Plate Tectonics is cause by convection currents in the mantle of the Earth. This theory was originally called continental drift. The theory of “Pangea” that is the continents were connected was Alfred Wegener. The age of the sea floor is one good piece of evidence that very adequately supports the theory of plate tectonics. The Ocean floor is around 160 million years old while the crust of the earth is around 3.8 billion years old. Another example is that the shapes of many continents are such that they look like they are separated pieces of a jig-saw puzzle. The fact that they are so properly shaped to fit together causes the plate tectonic theory to be properly supported by it. There is also large amount of seismic, volcanic, and geothermal activity along the conjectured plate boundaries. The concentration is striking, and indeed this plot serves to define the plate boundaries extremely well. The plotted earthquake and volcanic activity on the physiographic chart of the sea floor can be seen to follow along the plates, very few were far away from the plates. The earthquakes that were not close to the plate boundaries, like the one in England, was weaker and can be attributed to other reasons such as reduced weight stress from the melting of once glaciers that covered the area. The movement of the continents over a long period of time is measurable and has been done by many geologists. Another example is how there are ridges, such as the Mid-Atlantic Ridge where plates are separating that are produced by lava welling up from between the plates as they pull apart. Likewise, there are mountain ranges being formed where plates are pushing against each other such as the Himalayas, which are still...
Please join StudyMode to read the full document