Layers of the Earth Flashcards
Asthenosphere
Liquid, made of rock, convection currents, heated by the outer core through conduction. Convection currents cause the movement of tectonic plates.
Crust
Top layer. Thinnest, coolest, made of rock. Part of lithosphere.
Inner Core
Most inner layer. Most pressure, hottest, made of iron and nickel.
Lithosphere
Most rigid, solid layer. It is the crust and the upper mantle, which Mr. Martin may refer to as the “top of mantle,” so be prepared for that.
Mantle
Thickest layer. Top part and bottom part are solid, but the middle part is liquid-ish, at least enough for convection currents to happen. Made of rock and heated by outer core, which is heated by the inner core.
Outer core
Only completely liquid layer, although it goes through a lot of pressure. Its flow over the inner core may cause Earth’s magnetic field.
Oceanic Crust vs. Continental Crust
Oceanic Crust:
Basalt
More Dense
Younger
Thinner
Continental Crust:
Granite
Less Dense
Older
Thicker
Both:
Part of plates
Convection currents in mantle - D to A
Heating
A to B
Less dense, rock rises
B
Heated rock, less dense
B to C
Rock cooling, moving tectonic plates
C
Cooled rock, density increases
C to D
Sinking rock
D
Cool, dense rock
Law of superposition
Oldest layer on bottom, newest on top
Index fossils
Fossils geologists and paleontologists use to find the relative age of rock layers. They must be widespread.
How old is Earth?
4.54 byo. Around 4.6 billion years ago.
Intrusive vs. Extrusive
Intrusive:
Molten material seeps through but does not emerge on top of the crust. It forms a new, younger rock layer among much older rock layers.
Extrusive:
Molten material emerges on top of the crust. It continues to form new, young rock layers on top of the crust.
What happens when you go to the center of the earth?
As you go to the center of the Earth, temperature, density, and pressure increases.
