(RM) Rocks Lesson

Rocks

How do today's scientists know what they know about the fascinating animals that once inhabited the Earth? How do the

y know where prehistoric beasts lived, what they ate, and how they behaved? Part of the answer comes from studying rocks and fossils.

There are three types (classifications) of rock.

•Igneous - Rock formed when molten (melted) materials harden.

•Sedimentary - Rock formed from sediment (sand, mud, animal remains, etc) on the surface of the earth.

•Metamorphic - Rock that has been physically altered by heat and/or pressure.

Classifying Rocks

Notice the description of the three types of rock. Rocks are categorized into one of these three types based on the way they were formed. When studying a rock sample, geologists observe the rock's color and texture and determine its mineral composition. Once the geologist knows the rock's characteristics the rock can then be classified according to its origin, or where and how it formed.

Texture

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