Transcript Rocks Rock!
Rocks Rock! What are rocks? • Rocks are always underneath you. Even on water, there is rock beneath you. Rocks are made of minerals. Sometimes you see specks of different colors in a rock. Sometimes you see shiny specks. These different specks are the minerals in a rock. What are sedimentary rocks? • Millions of years ago, wind blew dust and sand into the lakes and oceans. The dust and sand settled to the bottom in layers called sediment. Seashells formed layers of sediment, too. Over time, the layers hardened into sedimentary rock we see today. Sedimentary rock comes from a word that means “ to settle.” Limestone, shale, and sandstone are sedimentary rocks. You can often find fossils in sedimentary rocks. What are igneous rocks? • Melted rock can push through cracks in the Earth’s crust. When the melted rock cools and hardens, it is called igneous rock. Sometimes it cools inside the earth and other times it becomes lava and cools outside the earth. Igneous comes from a word that means fire. Granite, obsidian, and pumice are igneous rocks. What are metamorphic rocks? • The deeper inside the crust of the earth, the hotter it gets. The rocks get harder, too. These are rocks that were changed from one kind to another kind due to heat, time, and pressure. Metamorphic rocks are rocks that have changed. Limestone changes to marble. Shale changes to slate. Sandstone changes to quartzite. What are the layers of the earth? • Under the earth’s crust there are pockets of melted rock. Below this is the mantle, made of hot, melted rock called magma. The outer core is liquid metal and the very center of the earth, the inner core, is a ball of solid metal! What is a volcano? • A volcano is an opening in the earth’s crust where melted rock can flow out. Volcanoes come in different shapes. This is how volcano is formed. Extreme heat inside the earth melts rocks, and magma is formed. The melting rock produces gases, which mix with the magma. The gas-filled magma begins to rise. Pressure slowly builds as the magma pushes against surrounding rock. The magma is so hot that it melts some of the surrounding rocks along the way, forming a conduit, a tube-like passageway. The magma travels through the conduit until it blasts an opening, called a vent, through a weak area of the earth’s surface. The gas is released, and the magma flows out of the vent as lava. The lava spills out onto the earth’s surface. It eventually cools and hardens into igneous rock. What are the layers of soil? • The deepest layer is called the substratum, or bedrock. Large rocks, sometimes broken up by longer tree roots, can be found here. Igneous rocks like granite and basalt can be formed here and metamorphic rocks like slate and marble can melt into magma. The middle layer is called the subsoil. Here you will find smaller rocks being broken up and rocks changing as they go through their rock cycle. Animals hibernate in the subsoil. A sedimentary rock like sandstone or shale may become metamorphic because of the pressure above. The top layer of soil is called topsoil. It is the richest soil because it is made of humus, or decaying plants and animals. Topsoil can easily be eroded away. The End! • We hope you enjoyed our slide show about GEOLOGY! We had fun making it and learning at the same time!