The Earth System contains a bewildering array of cycles in which matter is recycled again and again. Among the most important of these cycles is the Rock Cycle. Rocks comprising the solid Earth are constantly being formed, changed and reformed in what is termed the Rock Cycle.
Igneous rocks are formed when molten rock called magma solidifies. This magma can be derived from the melting of sedimentary, metamorphic, or pre-existing igneous rock.
Sedimentary rocks are produced from the hardening of sediment. In context of the rock cycle, we can regard sediment as being accumulations of particles of rock and individual minerals that result from the breakdown and erosion of igneous, metamorphic or pre-existing sedimentary rocks.
Metamorphic rocks are produced when igneous, sedimentary, or pre-existing metamorphic rocks are subjected to heat (and sometimes pressure) that is sufficient to significantly change the mineral makeup and stucture of the rock without melting it.
The Rock Cycle demonstrates
very well the notion that our Earth is the ultimate blue box. Recycling
is a global phenomenon ! The Earth does it - why shouldn't we ?