Geology. Rocks, minerals and landforms All photos, graphics, and text copyright 2007 by Kris Light.

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1 Geology Rocks, minerals and landforms All photos, graphics, and text copyright 2007 by Kris Light

2 Geology is the study of the earth Geo means earth - ology means study of Kris Light K. Light Arches NP - Utah

3 Layers of the earth Crust Outer core Inner Core Mantle The Inner Core is made of solid Iron and nickel, temperature 7,000-12,000ºF The Outer core is made of liquid iron and nickle The mantle is made of melted rock and minerals called magma, when it comes out of the crust it called lava The Crust is made of rock and soil; 3 25 miles thick

4 The Inner core The inner core is under such intense pressure (45 million pounds per square inch!) that the iron and nickle is solid despite the high temperatures! It is 800 miles thick and 4000 miles beneath the crust. Inner Core

5 The Outer Core Outer Core The Outer Core is made of liquid iron and nickle, ºF It is 1400 miles thick and 1800 miles below the crust

6 The mantle Magma The mantle is made up of molten rock; between 1600º and 4000ºF. The hotter magma rises and cooler sinks. It is 1800 miles thick. If magma comes out of the crust (volcano) it is called lava. Magma that cooled slowly under the crust often formed mountains Most common elements in the mantle are: magnesium, silicon, iron, and oxygen these elements can cool to make minerals.

7 Earth s Crust 5 25 miles thick The crust is made up of 2 kinds: Continental (lighter granite, andesite) and Oceanic (heavier basalt) The crust floats on top of the mantle Rising and sinking of magma causes movement of the crust resulting in earthquakes, volcanoes, and slow continental drift

8 Earth s Crust cross-section Magma is heated by the radioactive core. This hot liquid rock rises, as it cools it sinks causing movement Oceanic in the Crust Earth s crust, resulting in earthquakes. Volcanoes occur where there are weak spots in the crust and the magma is forced to the surface. When magma leaves a volcano it is called lava. The area of the Earth with The most earthquakes and volcanoes is called the Ring of Fire.

9 Minerals are the ingredients of rocks Granite is made up of: Feldspar Quartz Hornblende Mica Think of magma as being a giant stew pot for cooking rocks. Minerals from the mantle crystallize and cool beneath or above the surface to become igneous rocks. Granite is a type of rock made of 3 or 4 different minerals: Feldspar, Quartz, Hornblende, and sometimes mica.

10 The basic rock types: Igneous from fire this type of rock formed from magma either below the earth s surface or above it; the first kind of rock Types of igneous rock include: lava, scoria, pumice, andesite, obsidian, granite Sedimentary made up of weathered pieces of igneous or metamorphic rock. Types of sedimentary rock include: sandstone, limestone, shale, chert, conglomerate, breccia, flint, geode Metamorphic made up of rocks that have been changed by heat and pressure. Types of metamorphic rock include: gneiss, schist, marble

11 Igneous Rock K. Light Granite Igneous rock that cooled slowly beneath the crust formed large crystals (ex. granite) Igneous rock that cooled rapidly formed small crystals and some types contain air bubbles (obsidian, pumice, scoria). Scoria is a type of igneous rock that is called a lava bomb.

12 Granite in the field The highlight of Yosemite National Park, in eastern California, is the glacierscoured granite. This granite cooled beneath the earth millions of years ago. The granite boulder in the upper photo has a stripe that is made up mostly of white quartz and black crystals of horneblende. El Capitan, Yosemite NP K. Light K. Light K

13 K. Light Sedimentary rock Sedimentary rock is made up of smaller, weathered rocks that have settled and been cemented together. Conglomerate rock has rounded pebbles (as in this photo); breccia has small, angular rocks. Sandstone - Utah Conglomerate rock - TN

14 More types of sedimentary rock K. Light K. Light Shale is rock formed from fine mud. The shale in the southern Appalachian mountains has a silvery sheen to it. This boulder has been eroded by the small rocks. Chert is made up of very tiny quartz crystals. It is a very hard rock and is quite common in Oak Ridge, TN.

15 Limestone a sedimentary rock K. Light Fossils are often found in Sedimentary rock. Limestone is made of the shells of ancient marine animals such as this cephalopod and gastropod. The calcium carbonate (CaCO3) in the shells was compressed and petrified into stone. A test for limestone is to put a drop of hydrochloric acid on it to see if it bubbles.

16 Sedimentary Rocks in the field Sandstone Fall Creek Falls SP, TN K. Light Sandstone layers in Capitol Reef NP - Utah K. Light

17 Sedimentation jar Put rocks, sand,mud and water into a plastic drink bottle (tape the cap). Shake the mixture and let it settle. Parent Material: Rock it Becomes: Mud Sand Rocks Time, cementation Shale Sandstone Conglomerate or breccia

18 Weathering Weathering of rocks is caused by: ice, wind-blown sand, and water Wind-blown sand erosion - Arches NP, Utah K. Light Wave erosion - California River erosion Goosenecks - Utah K. Light Glacier ice Alaska K. Light K. Light

19 Metamorphic rock forms by: A. Heat - When rocks are exposed to a tremendous amount of heat and pressure beneath the surface, they buckle, bend and often melt. This changes the crystalline structure of the rock to make it become a new type of rock. When rock, such as granite, is compacted it pushes the minerals closer together making the new rock more dense and it often becomes striated (striped) or layered. Lava and magma coming in contact with rocks can cause them to change too. B. Pressure Rocks that are subjected to tremendous amounts of pressure, due to either burial under heavier rock or tectonic pressure can metamorphose. This can happen from 3 to nearly 25 miles beneath the surface of the earth. C. Chemical fluids When water is exposed to magma close to the surface, minerals are released into the seawater and settle out on the seafloor. Black smokers in the vent zones of the ocean floor belch out massive amounts of minerals. Ore deposits in mountain ranges formed in a similar way when water seeped through cracks in the rocks long ago.

20 Parent rock: Granite Limestone K. Light K. Light K. Light Shale Metamorphoses to: Gneiss Marble K. Light Slate K. Light K. Light

21 Metamorphic Rocks In the Field Gneiss Roan Mtn., TN K. Light K. Light Gneiss Boulder Denali NP, Alaska

22 See diagram on next slide Igneous rock is broken down into sediments, which eventually become sedimentary rock; it can also be transformed into metamorphic rock by heat and pressure; or it can be re-melted back into the magma. Sedimentary rock can be re-melted back into the magma to become igneous rock once again; it can also be transformed into metamorphic rock by heat and pressure; or it can be broken down into sediments, which eventually become sedimentary rock again. Metamorphic rock can be broken down into sediments, which eventually become sedimentary rock; or it can be re-melted back into the magma.

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24 Follow-up questions 1. What does geo mean? 2. What is the Earth s mantle made of? 3. Why is the iron and nickel in the inner core solid instead of liquid? 4. What is the temperature range of the mantle? 5. What is magma called when it reaches the surface? 6. What are the most common elements in the mantle? 7. What do those elements make when they cool and crystallize? 8. What are the two different types of crust and what are they made of? 9. What causes continental drift? 10. Which of the three basic rock types means from fire? 11. Which type of rock is called a lava bomb? 12. Name some igneous rocks that cooled rapidly. 13. What is chert made of? 14. How did limestone form? 15. What causes weathering of rocks? 16. What causes rocks to change and become metamorphic?

25 End of Presentation Kris Light