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M etamorphic R ocks. A. Vocabulary. 1. Parent rock : Preexisting rock 2. Recrystallization : A process in which rocks undergo change without truly melting. B. Key Ideas:. 1. Formed when existing rocks (igneous , sedimentary or metamorphic ) are changed by HEAT AND/OR PRESSURE
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A. Vocabulary 1. Parent rock: Preexisting rock 2. Recrystallization: A process in which rocks undergo change without truly melting
B. Key Ideas: 1. Formed when existing rocks (igneous, sedimentary or metamorphic) are changed by HEAT AND/OR PRESSURE 2. The new rocks may resemble the “parent” rock in their mineral composition/color 3. IMPORTANT- THE ORIGINAL ROCK CANNOT MELTWHEN IT BECOMES METAMORPHIC! (If it melts and solidifies, it’s igneous!)
Animation of Metamorphism • Metamorphism
1. REGIONAL: Large areas of rock are changed by HEAT & PRESSURE C. The 2 Types of Metamorphism
“Liquid hot magma!” 2. CONTACT: Magma touches layers of rock and theHEAT causes the rock layers to change a. Little to no pressureis involved with contact metamorphism (Contact Touch)
D. the bells & whistles for metamorphic rock identification 1. BANDING – alternating layers of different colored minerals due to sorting by density a. These bands are usually distortedfrom the heat&pressure b. not to be confused with sedimentary layers (stratification)!!!
FOLIATION 2. FOLIATION– mineral alignment– the minerals in the rock are layered, which causes breakages to often occur along flat surfaces- look for“scratches” in the rocks
More foliation – slate & phyllite Foliation – note the “scratches” in the rock – this is mineral alignment! Excellent example of banding & distortion – this is GNEISS Banding – mica schist
E. Difference Between Marble and Quartzite a. Both are white in color b. Marble reacts with HCl(hydrochloric acid) andquartzitedoes not because marbleiscomposed of recrystallizedCalcite
VIDEO • Watch the video and write down three notes from it!!! • https://www.youtube.com/watch?v=e15n7-zq0mA • If the link doesn’t work, search for “Geology Kitchen Metamorphic”
Remember… MORPHING is all about CHANGE! • Animoto Video
When I was young, liquid granite I was diagnosed schizophrenic Neither feldspar, nor mica, nor quartz But the sum of the three Bonded igneouslyThat means melted together for life Well, I was hot and dejected Oh, I was injected Under layers and layers of dirt But, it was there that I changed All my crystals rearranged Into G-N-E-I-S-S, gneiss So, take a look, and you'll see That I'm not what I used to be I've been touched metamorphicallyAll the heat and the pressure Have changed me forever So don't take me for granite, I'm gneiss The GNEISS SONG Well, I wasn't to been seen Until time changed the scene Exposing my face to the sun But, now its here that I sit Being worn down bit by bit Oh, erosion is wearing me down Refrain So, be aware, have a look Underground or underfoot For that beautiful pinky-gray face The Canadian shield Holds a magnamous yield Of the rock that was changed into gneiss Refrain
Okay… Let’s sum up!
There are 3 classifications of ROCKS • Igneous – formed by the cooling of magma (melted rock) • Sedimentary – formed by compaction & cementation of rock fragments • Metamorphic – formed by heat & pressure changing existing rocks
Remember the “bells & whistles” when identifying rocks! • Igneous – obvious crystals of different minerals • Sedimentary – stratification, fragments, fossils • Metamorphic – foliation, banding
Activity- Listen closely to directions! • 1. Send one group member to the front to pick up the playdough • 2. Carefully stack playdough slabs on top of each other without blending them in any way. • A. Of the rock types we have talked about already, which type forms like this? • 3. Now, fold the playdough layers in half and push down • 4. What are some observations?