New seas are formed due to plate tectonics. The upper layer of the Earth, called the lithosphere, is broken up into segments, which can move by sliding through the highly viscous liquid asthenosphere layer (upper mantle) below them. There are 7 or 8 large plates (known from the continental drift theory), as well as dozens of minor plates (there are even smaller ones called microplates). You can see some of them on the map below. The actual movement is very slow, typically at 1-4 cm (0.4-1.6 in) a year, with the fastest plate at 16 cm (6.3 in) a year. The interesting things happen at plate boundaries, where the plates collide, diverge, or slide past each other. Depending on the type of boundary and plate (continental or oceanic), different events occur, usually accompanied by volcanic activity. Volcanic islands may form, separating a part of the ocean, resulting in a new sea. A part of a continent may get lowered (if its plate is pushed under a colliding plate) below the sea level and flooded to form a sea. A rising plate may emerge above sea level to separate a part of an ocean or a sea to form a new one.
Click here to cancel reply.
Sorry,At this time user registration is disabled. We will open registration soon!
Don't have an account? Click Here to Signup
© Copyright GreenAnswers.com LLC