Explain the significance of fossils in sedimentary rocks.
fossil—A remnant or trace of an organism of a some earlier geologic age, such as a skeleton or leaf imprint, embedded and preserved in the earth's crust.
fossilization—the processes that turn plant or animal remains to stone.
Trace fossil—a fossil impression of a footprint, trail, burrow, or other trace of an animal rather than of the animal itself.
bioturbation—the stirring or mixing of sediment or soil by organisms, especially by burrowing, boring, crawling, feeding or other traces left by biological activity.