What Is the General Direction of Plate Movement?
Since the 19th Century, it has been theorized that the surface of the Earth was made up of plates that moved slowly. Many geological features visible on the Earth’s (and the ocean floor’s) surface were thought to be due to this movement. With modern GPS research on the movement of the surface of the Earth, the broad strokes of the theory of plate tectonics are proven, with questions remaining only over the details. Among other things, where the individual plates are actually going is now known.
The Lithosphere and Asthenosphere
The outer parts of the Earth can be divided into two layers. On the top is the lithosphere, which includes the visible crust of the Earth’s surface. It also includes the solid, uppermost part of the mantle. Beneath this is the asthenosphere. This material is solid and not at all like the liquid rock and metal found in the Earth’s core. However, it does have lower viscosity and sheer strength than the lithosphere. From the point of view of geological time (tens or hundreds of thousands of years), the best way to describe the relationship of the lithosphere to the asthenosphere is that the top floats on the bottom. As the lithosphere is made up of several distinct plates, this is the origin of plate tectonics.
A variety of physical forces explain the movements of plate tectonics. The first is convection or the movement and exchange of hot and cold substances. Underneath the lithosphere, a slow process of churning is present, raising hot material and sucking down cooler material. Another explanation is gravity. The cooler, thicker, denser material that is far from the ocean ridges causes gravity to pull material into the hotter mantle to balance the greater load. It is also believed that the gravitation of the moon has some impact on plate tectonics.
The general direction of most plate movement is toward the Pacific Ocean. Most of Asia, Africa, Europe and Australia are drifting eastward. North America and Greenland are drifting westward. Central and South America, and most of the Caribbean are drifting north, contrary to general trends. Different parts of Antarctica are drifting in different directions.
Plate tectonics explain a number of large-scale geological effects visible on the Earth’s surface. For example, it goes a long way to explain the formation of certain mountain ranges and the rise and fall of land masses over time. It is known that much of the land, including mountains, that are now dry and on the surface, were once underwater because of sea creature fossil evidence. Continental drift also explains the coastal “fit” between South America and Africa.
Sea Floor Spreading
This theory also explains the spreading of the sea floor. The plates include the entire surface of the Earth, dry and wet, and many plates embrace a lot of sea floor territory. When plates are pushed apart, the result is material from beneath the crust being pushed to the surface, creating wholly new stretches of sea floor.
Earthquakes are also a result of plate movement. Fault lines are common at or around plate boundaries, and plate movement results in a great deal of tension being built up in these areas. It is widely believed that earthquakes are a result of this plate tension snapping and suddenly being released.