The best method to correlating rock layers is through index fossils.
If we find fossils from oceanic animals in a desert area, we can assume that the area was once covered with water.
Fossils of tropical animals have been found in Antartica because Antartica used to be closer to the equator (think Pangea).
Mammals increased in number and humans developed in the Cenozoic Era.
Since tectonic plates are always moving around, the shape, location and placement of Earth's continents change over time (see Pangea link).
Earthquakes are caused by the movement of the plates - they displace and break rocks at the fault lines and the Earthquake is the shaking that radiates out fromt he breaking of the rock.
The lithosphere is composed of the Earth's upper mantle and crust.
The liquid layer of the Earth is the outer core - the inner core is pressed so tightly together that it is more like a solid.
The crust of the Earth is broken into plates - these plates are constantly moving.
Plate boundaries (more information here)
- Divergent boundaries -- where new crust is generated as the plates pull away from each other.
- Convergent boundaries -- where crust is destroyed as one plate dives under another.
- Transform boundaries -- where crust is neither produced nor destroyed as the plates slide horizontally past each other.
- Plate boundary zones -- broad belts in which boundaries are not well defined and the effects of plate interaction are unclear.
Convection currents are the circular motion in a liquid caused by heating and cooling.
PangeaSeafloor spreading - great animation here too!
Cooling rates influence the texture if the igneous rock:
- Quick cooling = fine grains
- Slow cooling = coarse grains
Sandstone formation
Gneiss formation
Basalt formation
Conglomerate rock
Earth's spinning core creates Earth's magnetic field.
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