The
rock cycle is illustrated in Figure
1 . Igneous rocks are produced when molten rock cools and solidifies. When exposed at the earth's surface, the rock is broken down into tiny particles of sediment by weathering and erosion. This weathered material is carried by water or wind to form sedimentary deposits such as beaches, sand bars, or deltas. The sediment is gradually buried by more sediment and subjected to higher pressure and temperature. It eventually hardens into sedimentary rock (
lithifies). If burial continues, the increasing pressure and temperature at depth recrystallizes the sedimentary rock into a metamorphic rock. The rock cycle is completed when the metamorphic rock becomes so hot that it melts and forms a magma again. Igneous and sedimentary rocks can become metamorphic rocks if they are buried deeply enough or are affected by plate tectonic processes. Metamorphic rocks exposed at the surface will also weather to form sedimentary deposits.
Introduction to Physical Geology
The Earth's Components
