Dictionary of Moisture Protection & Restoration

From magma to rock: When magma pours out of the Earth from volcanoes and dikes, it hardens rapidly as extrusive (volcanic) igneous rock. (This is the beginning of the stone process.) Over time, wind and rain can reduce all rock to sediment, including deeply buried intrusive rock, which is first exposed by erosion. Chemical bonding and pressure from above compact the sediment, transforming it into sedimentary rock. (These are products of erosion and weathering). The changes do not stop there. Extremely high heat and pressure can gradually alter all rocks into another type of rock, the metamorphic rock. The full circle is completed when rocks of all kinds are buried deep enough for the heat of the Earth’s core to melt them into magma once again.

76