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Analyzing how rocks are formed Presented by Austin Prater, III.

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1 Analyzing how rocks are formed Presented by Austin Prater, III

2  Can you think of any ways rocks are used in your everyday life?  Aren’t all rocks pretty much the same?  How will knowing the types of rocks help me in the future?  Did you know the all the rocks on Earth get recycled over time?


4  12.11.82 Indicate that the earth's crust is made from mostly igneous and metamorphic materials and was formed as a result of partial melting of part of the mantle rock. Know that there is a thin layer of sedimentary rock on top in many places.  12.11.87 Identify the properties of rocks and minerals based on the physical and chemical conditions in which they are formed, including plate tectonic processes.  12.E.4a Explain how external and internal energy sources drive Earth processes (e.g., solar energy drives weather patterns; internal heat drives plate tectonics).

5 After this unit’s activities students should be able to:  Identify the 3 types of rocks based on their physical characteristics  Describe the processes involved with the formation of the types of rock  Classify samples of rocks based on their features and informational tables


7 Here is another version of the Rock Cycle


9  Form by solidification (crystallization) of melted minerals  At the surface, LAVA hardens to form EXTRUSIVE rocks with tiny (FINE-GRAINED) crystals or GLASSY (no crystal) TEXTURES  Beneath the surface, MAGMA hardens to form INTRUSIVE rocks with easily visible (COARSE-GRAINED) crystal texture.

10  Light-colored, coarse- grained, no pattern  Mostly quartz, feldspar, mica, and hornblende  Often used for buildings and monuments

11  Dark-colored, fine- grained, extrusive  Formed where lava erupted onto surface  Most widespread igneous rocks  Found locally in the Palisades along west shore of Hudson River, Connecticut River valley

12  Dark-colored, coarse- grained intrusive  Similar composition to basalt—plagioclase feldspar with some pyroxene and olivine

13  Natural volcanic glass  Forms when lava cools very quickly  Usually dark, but small pieces may be clear  Fractures along curved (conchoidal) surface  Used as spear and arrow points, knives

14  Light colored, frothy (many air spaces)  Same minerals as in granite, but finer in grain size

15 Sedimentary Rocks Sedimentary rocks may be made of rock fragments— sediments—or by chemical reactions. The classification of sediments is shown below.



18  The most important of these is coal. Anthracite coal results from the greatest pressure and releases the most energy when burned. Other varieties are bituminous and lignite. “Petrified” (permineralized) wood is another organic rock.

19  Shale is the most common sedimentary rock  Sedimentary rocks cover about three- quarters of the land surface

20  Formed by heat and pressure changing existing rocks  REGIONAL METAMORPHIC affects a large area and results from plate tectonics  CONTACT METAMORPHISM affects rocks on a local scale, such as “baking” sedimentary rocks next to magma or lava

21 “Foliated” rocks contain much mica and other rocks that produce layering or banding Gneisses and schists are examples of layering within rocks



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