Basically the idea is that any type of rock (igneous, sedimentary, metamorphic) can be transformed into any other type of rock (igneous, sedimentary, metamorphic) if it is subjected to certain conditions.
For instance, a marine shale (sedimentary rock) can be transformed into a metamorphic rock (blueschist) when it reaches a subduction zone and is subjected to intense pressure.
An igneous rock (granite) can be transformed into a sedimentary rock (arkose sandstone) if it is subjected to physical and chemical weathering resulting in small particles of the granite being deposited in a river and lithified into a rock.
A metamorphic rock (hornfels) can be transformed into an igneous rock (gabbro) if it is heated to such a degree that it melts and recrystallizes.
It's called a cycle because it does not occur in a linear manner but rather a cyclic one.
Igneous rocks are rocks that come from lava oozing out of the earth and cooling. They can later become sedimentary.
Metamorphic rocks are rocks that have been changed through heat and pressure (usually from being buried really deep). These are usually old sedimentary rocks.
Sedimentary rocks are rocks that have been worn away by water and wind. They can be old sedimentary rock, metamorphic or igneous. They then form layers of sediment.
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Basically the idea is that any type of rock (igneous, sedimentary, metamorphic) can be transformed into any other type of rock (igneous, sedimentary, metamorphic) if it is subjected to certain conditions.
For instance, a marine shale (sedimentary rock) can be transformed into a metamorphic rock (blueschist) when it reaches a subduction zone and is subjected to intense pressure.
An igneous rock (granite) can be transformed into a sedimentary rock (arkose sandstone) if it is subjected to physical and chemical weathering resulting in small particles of the granite being deposited in a river and lithified into a rock.
A metamorphic rock (hornfels) can be transformed into an igneous rock (gabbro) if it is heated to such a degree that it melts and recrystallizes.
It's called a cycle because it does not occur in a linear manner but rather a cyclic one.
It is a big circle. See this web site for a diagram:
http://www.learner.org/interactives/rockcycle/diag...
Igneous rocks are rocks that come from lava oozing out of the earth and cooling. They can later become sedimentary.
Metamorphic rocks are rocks that have been changed through heat and pressure (usually from being buried really deep). These are usually old sedimentary rocks.
Sedimentary rocks are rocks that have been worn away by water and wind. They can be old sedimentary rock, metamorphic or igneous. They then form layers of sediment.