Chapter 18 Fossils and Geologic Time
Chapter 18 Fossils and Geologic Time
Chapter 18 Fossils and Geologic Time
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Figure <strong>18</strong>-2 Footprint Puzzle<br />
WHAT ARE FOSSILS? 417<br />
<strong>Fossils</strong> tell us more than just what life-forms inhabited<br />
Earth. They also provide clues to ancient environments. When<br />
paleontologists find fossil fish or the remains of other organisms<br />
that resemble modern life-forms that live in oceans or<br />
lakes, they infer that they are looking at an ancient underwater<br />
environment. Although most sedimentary rocks are the<br />
result of material deposited in water, l<strong>and</strong> derived sedimentary<br />
rocks are also common. Fossil wood, such as the petrified<br />
logs pictured in Figure <strong>18</strong>-3 on page 4<strong>18</strong>, helps scientists identify<br />
terrestrial sediments.
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