Types of Rocks

Types of Rocks Name: _____________________________________________________________________________ Period: ______ Date: ____________ Essential Question: How are rock formed? Rocks are not all the same! The three main types, or classes, of rock are sedimentary, metamorphic, and igneous and the differences among them have to do with how they are formed. Sedimentary Sedimentary rocks are formed from particles of sand, shells, pebbles, and other fragments of material. Together, all these particles are called sediment. Gradually, the sediment accumulates in layers and over a long period of time hardens into rock, this process is called lithification. Generally, sedimentary rock is fairly soft and may break apart or crumble easily. You can often see sand, pebbles, or stones in the rock, and it is usually the only type that contains fossils. Examples of this rock type include conglomerate and limestone. Metamorphic Metamorphic rocks are formed under the surface of the earth from the metamorphosis (change) that occurs due to intense heat and pressure (squeezing). The rocks that result from these processes often have ribbonlike layers and may have shiny crystals, formed by minerals growing slowly over time, on their surface. Examples of this rock type include gneiss and marble. Igneous Igneous rocks are formed when magma (molten rock deep within the earth) cools and hardens. Sometimes the magma cools inside the earth, and other times it erupts onto the surface from volcanoes (in this case, it is called lava). When lava cools very quickly, either small or no crystals form and the rock looks shiny and glasslike. Sometimes gas bubbles are trapped in the rock during the cooling process, leaving tiny holes and spaces in the rock. Examples of this rock type include basalt and obsidian. Clarifying Questions: 1. What are the three types or classes of rocks? Igneous, sedimentary, and metamorphic ______________________________________________________________________________ 2. Why do we have different kinds of rocks? Think! They form due to various processes like cooling of molten rock, sediment deposition, and alteration under heat and pressure ______________________________________________________________________________ From the accumulation and lithification of sediments 3. Sedimentary rocks are formed from ________________________________________________ ______________________________________________________________________________ Sediments 4. Particles of sand, shells, pebbles, and other fragments of material are classified as ___________ 5. What is lithification? Process of sediment compaction and cementation ______________________________________________________________________________ ______________________________________________________________________________ 6. Describe a sedimentary rock. Formed from compacted and cemented sediments, often layered ______________________________________________________________________________ ______________________________________________________________________________ Sedimentary rocks 7. Which type of rock can contain fossils? ______________________________________________ 8. Give two examples of sedimentary rock. Sandstone, limestone ______________________________________________________________________________ 9. How are metamorphic rocks formed? From existing rocks altered by heat and pressure ______________________________________________________________________________ ______________________________________________________________________________ 10. Describe a metamorphic rock. Altered texture and mineral composition due to heat and pressure ______________________________________________________________________________ ______________________________________________________________________________ 11. Give two examples of metamorphic rocks. Marble, quartzite ______________________________________________________________________________ 12. How do igneous rocks form? From the cooling and solidification of magma or lava ______________________________________________________________________________ ______________________________________________________________________________ 13. Describe the difference between magma and lava. Magma is underground molten rock, lava is molten rock on the surface ______________________________________________________________________________ ______________________________________________________________________________ 14. Describe the type of igneous rock that formed when the lava cooled quickly. Extrusive or volcanic rock ______________________________________________________________________________ ______________________________________________________________________________ 15. Give two examples of igneous rocks. Granite, basalt ______________________________________________________________________________ The Rock Cycle- any rock can become any type of rock depending upon certain conditions. Igneous rocks form when molten rock (magma and lava) cools and harden. They break down by weathering and the breakdown products are transported by erosion.The breakdown products are deposited to form sedimentary rocks. Sedimentary rocks are buried, subjected , pressure. Heat and pressure( without melting) change rocks, forming metamorphic rocks. Metamorphic rocks may eventually be heated enough to melt, forming a new generation of igneous rocks. Multiple choice: Write the letter of your answer on the blank before each number. You can use the choices more than once. B ____ 16. Lithification (ribbonlike layers) A. igneous rock C ____17. Intense heat and pressure, no melting B. sedimentary rock B ____18. Presence of fossil C. metamorphic rock A ____19. Formed from magma and lava D. Rock cycle C ____20. Have ribbonlike layers C _____21. Metamorphosis B _____22. Buried and subjected to pressure B _____23. Presence of sand, pebbles, or stones in the rock. B _____24. Weathering and erosion D _____25. Any rock can change into any type of rock.