The rock cycle describes how rocks are continuously transformed between three main types - igneous, sedimentary, and metamorphic rocks - through geological processes such as erosion, deposition, burial, melting, and crystallization. Igneous rock is weathered into sediment and deposited to form sedimentary rock, which is then buried and altered by heat and pressure into metamorphic rock. Metamorphic rock can be melted into magma and erupt as new igneous rock, restarting the cycle.

1. The Rock Cycle

2. A Cycle of Many Pathways
KEY CONCEPT: Forces deep inside the Earth
and at the surface produce a slow cycle that
builds, destroys, and changes rocks in the
crust.
◊ Igneous rock is turned into sediment by erosion. The
sediment is deposited and slowly becomes
sedimentary rock.
◊ The sedimentary rock is buried by more sediment
and heat and pressure cause it to change into
metamorphic rock.
◊ Metamorphic rock is forced into the mantle and melts
forming magma. Magma erupts and cools to form
igneous rock again.

3. How Does it Work?