To study all three types of rock, geologists evaluate the minerals of which they are composed.
Each mineral has distinct physical properties, and there are many tests to determine each of them.
The specimens can be tested for: In the 1960s, it was discovered that the Earth's lithosphere, which includes the crust and rigid uppermost portion of the upper mantle, is separated into tectonic plates that move across the plastically deforming, solid, upper mantle, which is called the asthenosphere.
This theory is supported by several types of observations, including seafloor spreading and the global distribution of mountain terrain and seismicity.
When a rock crystallizes from melt (magma or lava), it is an igneous rock.
This rock can be weathered and eroded, then redeposited and lithified into a sedimentary rock.
There are three major types of rock: igneous, sedimentary, and metamorphic.