# On The Topic of Plate Tectonics

## Our Earth

Plate Tectonics is the theory that the crust is divided into plates that move around and interact with each other. The inside of Earth is comprised of layers. The Earth has 3 main layers; the crust (which we live on), the Mantle (which the crust is on top of), and the Core (which is surrounded by the Mantle). The Core has two sub layers, the Inner Core and the Outer Core. The Inner Core is solid and the Outer core is liquid. All of the layers are important to survivability of the Human Race. The core gives off a magnetic field that protects us from high radiation. The Mantle gives us continental drift which moves the plates around on top of it. Now I just mentioned continental drift. Not many people know or understand what this is, so I will explain it to you. Continental drift is the theory developed by Abraham Ortelius and further explained by Alfred Wegner proposed that our crust is divided into plates that float on top of the mantle and move around. These plates move around due to convection in the mantle, which means that the semi-liquid mantle will flow around in a pattern due to convection. There is evidence of this in the fact that pieces of the same fossil have been found in two different continents and the fact that all the continents look like they were once part of the same thing (Africa and South America). Now that you know the plates aren't stuck in one place you must be wondering "How do they interact with other plates?" Well when plates meet, the area in-between them is called a boundary. These boundaries map out where the edges of the plate are. There are three main boundary types, There are transform boundaries, divergent (not the movie/book) boundaries, and there are convergent boundaries. These boundaries are all different ways that the plates interact with each other. Transform boundaries are when two plates are rubbing against each other, but not colliding; Divergent boundaries are when the plates are moving away from each other; and Convergent boundaries are when plates collide. There are sub-boundaries which are generally associated with their parent boundaries (told above), but the most notable one is the Convergent Subduction boundary. This boundary only forms when the two types of crust (Oceanic and Continental Crust) collide. The Oceanic crust being denser that the Continental crust gets sucked under the Continental Crust. This is called subduction. People will say that knowing this doesn't matter, but these boundaries do have an effect on human life. At transform boundaries, mighty earthquakes occur and can wreak havoc, an example of this being the earthquakes at the San Andreas fault in California. At divergent boundaries, long valleys/ridges and volcanoes can form, creating new land, an example being the African Rift Valley or the Mid-Atlantic Ridge. At convergent boundaries, high mountains and deep trenches can form with such examples as the San Marina Trench, the Andes Mountains in South America, or the Himalayas in India. So, not only does this effect nature, it can affect human life too. A little bit more on the Divergent boundaries; there is a sub-boundary that is formed when two oceanic plates are moving away from each other. This has not been named yet, but something cool does happen when this event occurs. As the two plates pull away from each other lava rises from the cracks which forms new crust. This is called sea-floor spreading, which was proposed by Henry Hess. This only further proves the theory of continental drift seeing as this only forms at known Oceanic Divergent Boundaries.

## The Ring of Fire

Not the Johnny Cash song.

The ring of fire is a chain of volcanic activity around the pacific. This area hold 90% of the world's earthquakes and 75% of the world's active and dormant volcanoes (it has 452 volcanoes total). This is directly linked to plate tectonics and only furthers the theory of continental drift.