The Rock Cycle

“A rock can melt, sink, erode, and reappear with a different mineral history.”

01 / PLAINLY

What it means, plainly

The rock cycle links processes that transform material among igneous, sedimentary, and metamorphic rocks.

02 / CONTEXT

A little more

Cooling forms igneous rock; erosion, deposition, and cementation produce sedimentary rock; heat, pressure, and fluids alter rock without melting it to form metamorphic rock. There is no mandatory circular route: any rock may follow different paths over millions of years.

03 / WHY IT MATTERS

Why it matters

It turns rocks into records of past environments and connects tectonics, climate, erosion, resources, and Earth's interior.

04 / EXAMPLE

A familiar example

Exposed granite can erode into sand, become cemented sandstone, be buried and transformed into quartzite, then return to the surface.

05 / LIMIT

What it does not mean

It is not a conveyor belt with three fixed steps; routes can pause, repeat, or skip stages depending on geological history.

06 / NOTICE

Notice it in your day

Choose a local stone and propose two possible routes into another rock class. Mark which evidence would distinguish the histories.

FINAL NOTE

The idea worth keeping

Identify the process transforming the rock rather than only naming its final category.

QUESTIONS / 02

Questions people still have

Must a rock pass through all three classes in order?

No. Many routes exist, and a rock may repeat processes or skip entire categories.

What separates metamorphism from melting?

Metamorphism changes minerals and texture in the solid state; melting makes magma that may later crystallize.