Final answer:
The initial formation of Earth involved the solidification and cooling of rocks that fall into one of three categories: igneous, sedimentary, or metamorphic.
Step-by-step explanation:
Igneous rocks form when magma or lava cools and solidifies. Sedimentary rocks form when broken pieces of other rocks from weathering processes get cemented together or when minerals precipitate out of a solution. Metamorphic rocks are pre-existing rocks that are altered by heat and pressure.