Presentation on theme: "The Earth is divided into layers by density. As the Earth solidified during the formation of the solar system elements with higher density were drawn."— Presentation transcript:
The Earth is divided into layers by density. As the Earth solidified during the formation of the solar system elements with higher density were drawn toward the center of the Earth by gravity.
Oceanic crust is comprised mainly of the rock basalt
Continental crust makes up the land masses. This thicker, less dense material allows the continents to rise above sea level and remain dry for very long periods Continental crust is made primarily of the rock granite
As the very hot core heats the material in the Mantle it causes the material to move in a circular pattern. The mantle material heats up and rises and then cools and sinks. This circular pattern of movement within the mantle (called a convection current) pushes the lithospheric plates as they float. The movement and interaction of these plates causes most of the large scale changes on Earth's surface.
The plates do not remain still. They slide across the partially molten mantle material of the asthenosphere as a result of convection currents deep in the Earth’s interior.
Tectonic plates interact at places called plate boundaries.
Typically, since the Earth is spherical the plate boundaries would appear as the threads of a baseball weaving through the mid-ocean rifts and around the smaller plates.
Notice that ALL of the major plates include both continental and oceanic crust
Some plates move towards each other, some move away, and some slide horizontally past each other. Each interaction results in geologic process and characteristics that we can now associate with it.
Divergent boundaries are places where tectonic plates are moving apart
Most divergent boundaries are found on the seafloor where they form mid-ocean ridges
Iceland is a continuation of the Atlantic mid- ocean ridge
The Arabian Peninsula is an example of a newly formed divergent boundary as it separates from the rest of Africa
Convergent boundaries are where plates move toward each other. These boundaries give us the most interesting geologic features. There are three types of convergent boundaries
Oceanic crust to oceanic crust results in the subduction of one of the two plates and an island arc
Subduction is the process of one plate descending beneath the other