Rock cycle

Under the cycle of rocks or sometimes referred to simply as recycling, are understood in geology those cycle, fall into the rocks of the earth's surface to the depths and back will return to the surface. This cycle lasts roughly an average of about 200 million years, but with a very large statistical span.

Basics

The different rock types and individual rocks are transformed by forces of Geodynamics (erosion, sedimentation, metamorphism, etc) into each other. Plate tectonics leads especially in subduction zones to a kind of slow convection between Erdinnerem and crust and to a drift of oceanic and continental plates ( a few centimeters per year).

Over time, rocks weather due to the influence of wind, water, ice, and daily and seasonal temperature differences. These weathering products form then short the pedosphere ( the ground ), go into solution in water (chemicals), are transported as dust, and the like. The long term, but they are deposited from stable, petrifizieren ( " petrify " ) and form sedimentary rocks, are shipped in depth, and after transformation ( metamorphosis ) pushed back to days.

The true duration of the rock cycle is dependent on the geological- tectonic structure of the region and the moving forces. The latter come from erosion, mountain building, faulting and volcanism, but mainly by the plate tectonics. In addition, certain minerals are essential to weathering resistant than others, which leads to that, especially zircons can reach very old age, while the rock in which these zircons are crystallized once, has long been weathered.

It does not capture all packets rock in equal measure, but is an approximate average value. The oldest rocks on Earth, who are open - that is exposed on the surface - are believed to be 4.28 billion years old and - geological terms - already close tightly to the epochs of formation of the earth as ( superficially ) body.

Diagram of rock cycle

The following diagram shows how the groups of rocks that occur on Earth, be converted into one another:

The rock classes are:

• Sedimentary rocks or Absetzgesteine ​​(causes mechanical, thermal or chemical)
• Igneous rocks ( plutonic and volcanic rocks )
• Metamorphic rocks ( using heat and pressure in the lithosphere converted, for example granite gneiss).

The processes are:

• Diagenesis ( solidification )
• Weathering
• Erosion
• Melting ( anatexis )
• Solidification ( crystallization)
• Metamorphosis
• Sedimentation