What Are Sedimentary Rocks Natalie Hyde Crabtree Publishing Company www crabtreebooks com
WHERE DID IT ALL BEGIN WEAK OR STRONG Some sedimentary rocks such as shale are so soft you can crumble them in your hand Others such as quartz sandstone are so hard you can barely break them apart with a sledgehammer 왔 Shale is a rather soft sedimentary rock O ut of the three types of rock igneous sedimentary and metamorphic sedimentary is the most common It is made up of layers of small particles that are pressed and cemented tightly together CLASTIC ROCKS Different kinds of particles make different kinds of sedimentary rocks Sandstone and shale are made up of bits of other rocks and minerals and are called clastic rocks ORGANIC ROCKS Other sedimentary rocks such as coal or chalk are mostly formed by the remains of plants or animals Because they are made up mostly of things that were once alive they are called organic sedimentary rocks 왘 Coal is the largest source of energy for the generation of electricity 왘 Nearly 40 major sedimentary rock layers are exposed in the Grand Canyon 4
BRING OUT YOUR DEAD Fossils are found in sedimentary rock They are the ancient remains of plants and animals 왘 Well-preserved fossil of a prehistoric fish 왗 Limestone rock is made up mostly of calcite CHEMICAL ROCKS Minerals or chemicals form the third type of sedimentary rocks For example limestone is made up mostly of a mineral called calcite It is known as a chemical sedimentary rock spoon sand water MAKE YOUR OWN ROCK Have an adult help you with this activity You will need mixing bowl small paper cup Epsom salts Mix 1 cup of water and ½ cup of Epsom salts in a mixing bowl Stir until most of the salts have dissolved Fill a paper cup halfway with sand Now add just enough salt solution to wet the sand Let dry for two or three days Cut away the paper cup Where did the salt go How did it help form the rock 5
