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Summary: Rocks are made in different ways, with sedimentary rocks being made from erosion and deposition of preexisting rocks, and metamorphic rocks being made when preexisting rocks melt and recrystallize. Find out how igneous rocks are made with help from a lab manager and research scientist in this free video on rocks.
Jane Stammer is a lab manager and research scientist in the Advanced Mineralogy Research Center at the Colorado School Of Mines. Stammer has a master's degree in geology.read more
"Hi I'm Jane Stammer from the Colorado School of Mines and I'm here to answer questions on how rocks are made. Depending on the type of rock you're interested in, they're made in different ways. Sedimentary rocks are made from the erosion and deposition of preexisting rocks. They are deposited in low lying areas either in a valley or a stream or in the sea and over time they accumulate different sediments and get buried and compacted and form rocks. Igneous rocks are formed both under the ground and above ground by pools of magma and when these magmas cool down, they crystallize and form minerals which later coalesce and form rocks. Finally metamorphic rocks are made deep under the ground at very high temperatures and pressures and preexisting rocks remelt, recrystallize and form new metamorphic rocks. And that is how rocks are made."
eHow Article: How Are Rocks Made?