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Science Connection The Constantly Changing Rock Cycle By David Cochran US Geologic Survey Sedimentary sandstone US Dept. of Interior Metamorphic gneiss Wilson 44691 Wikipedia Commons Igneous gabbro There is nothing really new among rocks. The elements and compounds that make up rocks, like all matter, cannot be created or destroyed. But there is a lot of changing from one kind of rock to another going on, constantly. This change is called the rock cycle. Metamorphic Rock Over millions of years, layers of sedimentary rock press deeper and deeper into the Earth. More rocks pile on top creating great pressure. Deep in the earth, heat from the magma, pressure from layers and layers of rock above, and underground chemical changes cause rocks to combine and change forms. This Igneous Rock Deep inside the Earth, elements and compounds in change is called metamorphosis. Marble is the mantle are heating to a slow boil. This molten metamorphosed limestone. Quartzite is mixture of minerals is called magma. It is the stuff metamorphosed sandstone. that igneous rocks are made of. Over time, the magma As metamorphic rock is pressed deeper and deeper, cools. If it cools beneath the Earth’s surface, it forms it gets hotter and hotter. It finally melts into magma. into igneous rocks of granite and feldspar with mineral A volcano erupts, spewing new lava on the Earth’s crystals all about the same size. On the surface of the surface. The rock cycle begins again. Earth, igneous rocks form when the magma, as lava, Activities pours out through fissures and volcanoes. All igneous 1. See more examples of the three types of rocks rocks have inter-grown crystal patterns that form in at: http://www.rocksforkids.com/RFK/ the cooling magma. It is in igneous rock that veins of howrocks.html#Igneous. mineral ores such as gold, iron, and zinc can be found. 2. Go to: http://library.thinkquest.org/J002289/ cycle.html Read the information on Rock Cycle. Click on Fun Activities at the bottom of the page. Choose and complete: Famous Rocks Scavenger Hunt. Sedimentary Rock Once on the Earth’s surface, natural actions of wind, running water, waves, currents, ice, and gravity erode and move fragments of igneous and other rocks, grinding them into tiny pieces of sediment. This sediment is usually deposited in layers at a lower elevation. Here it can gather plant and animal remains. Over millions of years, the sediment is compressed and cemented together forming sedimentary rock. This is where most fossils, telling the history of our planet, are discovered. In sedimentary sandstone, some rock forms called “paint pots,” once used by American Indians, can be found. See the article on paint pots on page 26. SPIGOT 3. Go to: http://www.kidsgeo.com/geologygames/rocks-game.php and play the Rock Types Game to learn more about rock types. 1 Rocks and Minerals Science Connection For More Information See the Rocks and Minerals publication at Spigot Science http://www.spigotscience.com SPIGOT 2 Rocks and Minerals
