What is the rock cycle explain breifly?

The rock cycle is the full "life" of a rock from its original formation to its demise through weathering, and rebirth through recrystallization and extrusion. The rock cycle was first described by the geologist James Hutton. The concept of the rock cycle is considered by many to be the basic outline of physical geology.

There are five stages in the typical rock cycle:

1. Crystallizing magma cools into "new" rocks (Why do we say "new" rocks? Are not all rocks the same age?).
2. Then weathering breaks the rocks into smaller fragments which are then transported via rivers or wind, then deposited at the beach.
3. This sediment then undergoes lithification, cementation, and compaction into new sedimentary rock.
4. After millions of years resting and accumulating on the sea floor, subduction finally pulls these sediments down where they are melted and metamorphized into new rock material.
5. Then this material is melted and extruded again at the surface of the Earth, the rock cycle is complete, and a "new" rock is born.
An entire rock's cycle may take millions or even billions of years, depending on where the rock is deposited and how long it is "stuck" in any of the five stages of the rock cycle.

There are three basic rock types in the rock cycle. The first rock type is igneous rock, which originates when molten lava cools and solidifies. This process is called crystallization, and may occur at depth or at the surface of the Earth. The igneous rock, now at the surface, is exposed to weathering and erosion. These processes break it down into sediment, which is then transported via river or wind and deposited as sediment at the bottom of the sea.

Lithification, which means "conversion into rock", of the sediment forms a new sedimentary rock, which is the second kind of rock in the cycle. The sedimentary rock will then eventually be subducted, or taken underground, into the crust of the Earth and melted into metamorphic rock.

This new metamorphic rock is the third kind of rock, and will then eventually be melted and then rise to the surface of the Earth (again) and be extruded as new rock.

This full cycle does not always take place, as this is an idealized rock cycle. What actually happens to each individual rock in reality can vary greatly. Some rocks take "short cuts" in the rock cycle. For example, a piece of lava that cools into a new rock may then immediately be re-melted and mixed with other rocks to become a new metamorphic rock variety; all of this without ever being a sedimentary rock.