This week we begin our study of the
Layers of the Earth.
Earth has several layers. Many geologists believe that as the Earth cooled the heavier, denser materials sank to the center and the lighter materials rose to the top. Because of this, the crust is made of the lightest materials (rock- basalts and granites) and the core consists of heavy metals (nickel and iron).
The Inner Core is a solid sphere of metal, mainly nickel and iron, at Earth’s center. The Outer Core is a layer of molten metal, also mainly nickel and iron that surrounds Earth’s inner core. The Mantle is the layer of rock between Earth’s outer core and crust, in which most rock is hot enough to flow in convection currents. It is also Earth’s thickest layer. The Crust is a thin outer layer of rock above a planet’s mantle, including all dry land and ocean basins. Earth’s continental crust is 40 kilometers thick on average and oceanic crust is 7 kilometers thick on average.
The Lithosphere is the layer of Earth made up of the crust and the rigid rock of the upper mantle, averaging about 40 kilometers thick and broken into tectonic plates. It is cracked, and makes up the Tectonic Plates of the earth’s surface. Tectonic Plates are large, moving pieces into which Earth’s lithosphere is broken and which commonly carries both oceanic and continental crust. Look at the diagram below to see the various layers.
The Asthenosphere is the layer in Earth’s upper mantle and directly under the lithosphere in which rock is soft and weak because it is close to melting. The lithosphere ‘floats’ on the asthenosphere.
Notes we took in class on the SmartBoard!
Click on the picture below to take you to an interactive animation describing
Click on the pics below to look at the animations we used in class.
See the Layers of the Earth in Detail