The rock cycle — Geography, 11–13
See how rocks change form over very long periods, instead of treating them as permanent pieces of Earth.
Rocks have a life story
A rock can melt, cool, crack, be carried away, or be squeezed deep underground. These changes turn one kind of rock into another, so Earth’s rocks are part of a slow cycle rather than a fixed collection. The cycle may take millions of years.
Why use a cycle?
If you only name igneous, sedimentary and metamorphic rocks, the labels seem like three separate boxes. The cycle was developed to explain how rocks found at the surface can be changed by heat, pressure, weathering and burial. It solves the problem of describing change, not just appearance.
From mountain to new rock
Imagine granite exposed on a mountain. First, rain and ice break it into grains; a river carries them away. The grains settle in layers, become pressed and cemented into sedimentary rock, and later heat and pressure may change it into metamorphic rock.
The cycle is not a neat circle
A common mistake is to draw every rock moving through the same steps in the same order. That feels sensible because a circle suggests one regular route. In reality, a rock can skip stages, follow several paths, or remain unchanged for a very long time.
Reading the landscape
Geographers use the rock cycle to explain why one place has cliffs, another has rounded pebbles, and another has layers of rock. It also helps engineers choose building stone and understand where caves, soils or useful minerals may form. The cycle links visible landscapes to hidden processes.
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