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Fossils SOL 5.7 What are Fossils? • Fossils are the remains of ancient plants and animals. • These plants and animals lived many thousands or millions of years ago. • Fossils are relatively rare. How are fossils made? • First, remember that fossils can only be preserved in sedimentary rocks. • Sedimentary rocks did not start out as rocks, they started as mud or silt. • Time and pressure made the mud and silt into rock. Fossil Formation • 1. An animal or plant dies. It falls into a river, stream, pond or sometimes sand and is buried quickly. • 2. Over time, the remains are replaced by minerals that seep into the bone. • 3. Years later, if the rock is exposed, we find it as a fossil. Kinds of fossils • Cast. – usually hard shelled animals like a shellfish or trilobite will form a cast. The animal died and decayed, minerals filled the space it was in and made a cast of it. Kinds of fossils • Impression – Ferns, skin and sometimes even feathers are pressed into the mud or silt and then the impression is quickly buried, leaving a perfect copy of itself. Kinds of fossils • Footprints – When animals walk through mud or silt it is sometimes buried and filled with mud, making a perfect copy of the footprint. Fossil Fuels • • • • There are three kinds of fossil fuels. Coal Oil Natural Gas Coal • Coal is the ancient fossil remains of plants. • Ancient swamps piled up huge amounts of plants that were buried, locking the carbon into the plants. This made coal over time. Oil • Oil is the remains of ancient marine micro animals. • Plankton and other microscopic organisms died in the oceans and piled up. They were buried and produced oil. Natural Gas • Natural Gas is formed as the byproduct of decay. • Animals and plants die and when they decay they release gasses that are trapped. This forms a Natural Gas pocket.