Igneous Rocks

Igneous rock is formed when magma cools and makes crystals.
Magma is a hot liquid made of melted minerals. The minerals can form crystals when they cool.
Igneous rock can form underground, where the magma cools slowly or igneous rock can form above ground, where the magma cools quickly.

Sedimentay Rocks

Sedimentary rocks form at or near the earth's surface at relatively low temperatures and pressures primarily by:
deposition by water, wind or ice
precipitation from solution (may be biologically mediated)
growth in position by organic processes (e.g., carbonate reefs )

Sediment can either be:
Material, originally suspended in a liquid, that settles at the bottom of the liquid when it is left standing for a long time
Material eroded from preexisting rocks that is transported by water, wind, or ice and deposited elsewhere

Metamorphic Rock

Metamorphic Rock is formed when rocky material experiences intense heat and pressure in the crust of the earth.
Through the metamorphic process, both igneous rocks and sedimentary rocks can change into metamorphic rocks, and a metamorphic rock can change into another type of metamorphic rock.
Heat and pressure do not change the chemical makeup of the parent rocks but they do change the mineral structure and physical properties of those rocks.

Metamorphic rocks trapped underground are still subject to enormous heat from rising magma, or heated water, and pressure. Sometimes the heat can get so intense the rocks actually melt.
Pressure comes from the incredible weight of material surrounding the rock on all sides.
The pressure pushes new minerals into the rock and drives other minerals out; the result, of course, is that the rock is chemically changed.

Weathering

The process in which rocks are broken down by chemical and/or physical mechanisms into smaller particles.
There are three types of weathering
Physical weathering: physical action which breaks up rocks. An example of this is freethaw weathering
Chemical Weathering: when the rock is attacked by chemicals. An example of this is how acid rain breaks down limestone.
Biological weathering: occurs when rocks are weakened and broken down by animals and plants. A tree root system that is slowly splitting rocks is an example of this type of weathering..

Erosion is the wearing away of exposed surfaces by agents such as wind, moving water and ice. These agents usually contain weathered rock debris. Rock fall under gravity is also erosion.
Erosion influences orogenesis by changing the topography and hence the thickness of the deforming orogen, which, in turn results in modification of the gravitational force relative to the tectonic driving force. Whereas efficient erosion tends to localize deformation within a relatively narrow belt, decrease in erosional efficiency causes deformation to propagate toward more distal sites.




Transportation: This process occurs when the particles created by weathering are carried by ice, air, or water to a region of lower energy known as a sedimentary basin.

Melting

Melting is the result of continued heating
Leads to production of magma and new igneous rocks which are formed when the the magma cools.
This process depends on the size of the reservoir that it drains and the relative intensity or activity of plate tectonics.