(RM) The Rock Cycle Lesson

The Rock Cycle

How can a rock change from one form to another?

The concept of the rock cycle is attributed to James Hutton (1726—1797), the 18th-century founder of modern geology. The main idea is that rocks are continually changing from one type to another and back again, as forces inside the earth bring them closer to the surface (where they are weathered, eroded, and compacted) and forces on the earth sink them back down (where they are heated, pressed, and melted). So the elements that make up rocks are never created or destroyed — instead, they are constantly being recycled. The rock cycle helps us to see that the earth is like a giant rock recycling machine!

Forces inside Earth can place rocks under extremely high amounts of heat and pressure. Subjecting rocks to this heat and pressure will change them into metamorphic rock. Heat can melt rocks, changing them to igneous rocks. Rocks on the surface are exposed to weathering and particles can be transported and later go through deposition. Compaction and cementation will create sedimentary rocks from these once loose particles.

Some cycles simply go round and round in a nice neat circle. The Rock Cycle, however, can follow many paths. Look at the diagram of the rock cycle.

Rock Cycle Parts

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