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Name ______________KEY_____________________ Date _______ Per ____ Doc ____ Rocks Study Guide Be sure to review your labs, notes, textbook, and graphic organizers. You will have a lab practical portion to the test. This study guide is to help you study; it is not the only thing you should study. What is a rock?____________________________________________________________________ What are the 3 types of rocks? Igneous, Sedimentary, Metamorphic Match the 3 types of rocks to the way that they are produced: Igneous Produced from melted or molten rock cooling. Magma or lava cooling. Sedimentary Produced from lots of weathered and eroded rocks or organisms that have been deposited, compressed, and cemented together. The process of gluing sediments into stone is called lithification. Metamorphic Produced from adding heat and or pressure to existing rocks to produce a new rock called a daughter rock. Igneous Rocks How are igneous rocks formed? Melting, cooling and crystallization Why can’t you find fossils in igneous rock? Any remains would be melted Mineral Content - Felsic vs Mafic: Mafic rocks are dense and have little silica, but lots of Mg and Fe. They are usually a DARK color. Felsic rocks are less dense and have lots of silica and feldspar. They are usually a LIGHT color. Origin, cooling rate & Texture: quickly glassy very quickly slowly porphyritic large Word bank: coarse-grained fine grained coarse-grains on a fine background small Itrusive rocks form from the cooling of magma within the earth’s crust. This magma cools slowly and, as a result coarse - grained (large crystal size) forms. Extrusive rocks form from the cooling of lava on the surface of earth’s crust. Lava flowing down the side of a volcano cools quickly and, as a result fine - grained texture small crystal size) forms. Lava that cools in the air cools very quickly and as a result has a glassy texture which means that no crystals are visible. Note: pumice and scoria look like rocky sponges. They do not look like glass, but are still glassy because they have no visible crystals. Porphyritic rocks started cooling slowly and ended cooling quickly. As a result they have a porhyritic texture which is described as having both coarse-grains on a fine background Be able to look at a rock and tell its mineral content, origin, cooling rate, and texture. Mineral content: Mafic (dark) or felsic (light) Origin Cooling Rate Texture Intrusive slow Extrusive Fast or REALLY fast Fine-grained or glassy Porphyritic Slow then fast CoarseBOTH large grained & small (small or none) (large) crystals What is the relationship between origin and crystal size? The faster the rock cooled, the smaller the crystal size. Inside the earth, rocks cool slowly, outside the earth they cool quickly. Therefore, rocks formed inside the earth(intrusive) have larger crystals than rocks formed outside(extrusive). Sedimentary Rocks Sedimentary rocks are formed by the LITHIFICATION of sediments. List and describe the 5 steps. Step Description 1. Weathering Rocks are broken down by various processes 2. Erosion Sediments are moved to a new location 3. Deposition Sediments are dropped off 4. Compaction Sediments are pressed together 5. Cementation Sediments are “glued” together with a mineral ‘cement’ The law of superposition states that layers that are deeper down must have been deposited first and are therefore older than the layers above them. In the diagram below which layer is the oldest? C newest? A What is stratification and why can it happen? Stratification is the formation of layers as sediments are deposited over time Is there a relationship between the type of sedimentary rock and if it is stratified? No, there are examples of all types of sedimentary rock that are stratified and unstratified. What are the 3 types of sedimentary rock? How is each formed? Clastic bits of other rocks cemented together.(pebbles, mud, sand, clay). Organic bits of organisms that were once alive glue together by minerals. Chemical formed by evaporation or precipitation of minerals out of a solution. Why is coal organic sedimentary? Formed from decayed plant material Circle the stratified rock(s) pictured below. Label each as clastic (CL) , chemical (CH) or organic (O) Conglomerate Clastic Sandstone Clastic Coquina (made of shells) Organic Coal (from plants) Organic Geode Chemical Metamorphic Rocks Complete the diagram with the following words: (one word is used 2 times) dynamic thermal contact local regional heat pressure foliated foliated Dynamic Area size = Regional Contact or Thermal Area size = Local magma Mountain building & Tectonic Plates High PRESSURE & heat cause minerals to layer in the rocks. Layered rocks are called foliated Near magma chambers HEAT causes minerals to chemically change These rocks do not have layers so they are nonfoliated non The following image shows foliation. Which kind of metamorphism produces foliation? Dynamic Why does dynamic metamorphism produce foliation while thermal/contact does not? Pressure causes the mineral crystals to line up Why are metamorphic rocks called daughter rocks? They are formed from other rocks Which types of rocks can be parent rocks? Igneous, Sedimentary and Metamorphic Why would fossils be deformed if they were found in metamorphic rock? Heat softens and pressure Look at the image of gneiss to the left, is gneiss foliated or non-foliated Foliated Is gneiss formed by Dynamic or Thermal/Contact metamorphism? Dynamic ALL ROCKS: Identify the following statements as Igenous ( I ), Sedimentary (S) or Metamorphic (M): __S__ stratified or unstratified _M__foliated or nonfoliated __M__regional or local __S_most likely to have fossils __I__magma & lava __I__intrusive & extrusive __M__heat & pressure __I__ felsic or mafic ___I__deep in the earth __I__surface/volcanoes __M_changed by magma, mountains or tectonics __S__clastic, organic, chemical __M__ deformed fossils ___S__ lithification __M___parent and daughter __S__ layers over time __I__coarse, fine, or glassy texture Label the rock cycle and be able to explain what is going on. Word bank: Igneous Melted rocks Metamorphic Sedimentary Sediment Igneous Weathering & erosion Cooling crystallization Sediment Melted rocks Deposition, compaction, cementation (lithification) Melting Metamorphic Sedimentary Heat Pressure One type of rock can become ANY other type of rock.
