Rocks look like they last forever — but over millions of years they are slowly turning into other rocks. Today you'll learn how, then you will predict what each rock becomes.
Before we start — a rock looks like it lasts forever — but do you think one kind of rock could ever turn into another?
Igneous rock forms when melted rock cools and hardens. Sedimentary rock forms when bits of rock are squashed into layers. Metamorphic rock forms when a rock is changed by heat and pressure.
Weathering & erosion break a rock into tiny bits and carry them away. Deep underground, heat & pressure squeeze a rock into a new one. And if it gets hot enough to melt, it becomes magma — which can cool into rock again.
These changes link up into a loop with no beginning and no end. Given the right process and enough time, any rock can turn into any other kind — even back into the one it started as.