Internet Interactive Rock Cycle Directions: Go to the website http://www.uky.edu/as/geology/howell/goodies/elearning/module05swf.swf and answer the questions below. Part I: Igneous Rocks (click on Igneous Rocks) 1. What is the Latin word for igneous rocks and what does it mean? 2. How are igneous rocks formed? 3. Where does the magma come from? Intrusives: Commonly, magma before it reaches the earth's surface, forming (also called ) rocks such as, diorite, and gabbro. It may take thousands of years or longer for magma to cool and form plutonic rocks. 4. Why does it take thousands of years or longer for magma to cool and form plutonic rocks? Extrusives: Molten rock that does reach the earth's surface is referred to as "lava." Lava quickly (within hours or minutes) to form volcanic (or "extrusive") rocks such as rhyolite, andesite, and. Lava is still very hot when it erupts from the earth's surface, but it rapidly loses its heat to the atmosphere or the ocean. Crystal Size: rocks look very different from rocks because they and at such different rates. cools, so mineral have plenty of time to. Therefore, plutonic rocks have large mineral crystals that are visible to the naked eye. rocks, on the other hand, cool before mineral crystals have much of a chance to grow. In fact, some volcanic rocks (tuff, obsidian) are composed almost entirely of volcanic glass, which has no crystal structure. Melting: In a solid the molecules (or ions) are bound together in a regular repeating pattern. Minerals are crystalline solids, just like ice, and so they melt in the same way. But rocks usually of more than one type of mineral, each of which has its own distinct melting point. So rock melts in successive steps as it is heated beyond the melting point of each of its minerals. Partial Melting: Often preexisting rock melts only partially, creating magma consisting of the minerals with low melting points and leaving behind a rock made up of minerals with high melting temperatures. Other factors also control the melting of rock. The water included in the rock, either in pore spaces or in the mineral structure, the the melting point (temperature at which the rock melts). This is one reason that volcanoes are typically found near subduction zones. oceanic crust carries water downward with it, down below the hot dry of the overriding plate. The water then rises into the upper plate and lowers the melting temperature of the lithosphere rocks, creating magma from partial melting.
Cooling and Crystallization: Click Crystallize Draw a picture illustrating (showing) extrusive versus intrusive crystallization. As cools, minerals begin to. As heat dissipates, the temperature drops below the melting point of each mineral in succession, causing the minerals to crystallize in order from highest melting point to lowest melting point. So the order in which minerals crystallize is the of the order in which they melt. Intrusive versus Extrusive: Only, microscopic grow in rocks because they so. magma very, allowing time for crystals to grow to be visible to the naked eye. Glassy Texture: In some cases, lava cools so rapidly that very if any are formed. With no crystal structure, the ions in the lava solidify in a random manner, resulting in. This "glass" is usually very dark and translucent, and such glassy igneous rocks are called "." Some of the material that erupts from volcanoes, such as fine-grained (called "ash"), becomes rather than volcanic rock. Ash cools very quickly as it is thrown from an erupting volcano, and it is usually glassy in texture. Interpreting Rocks: The style of volcanic eruptions and the appearance of volcanic rocks vary dramatically. But knowledge about the cooling history of igneous rocks is a key first step in interpreting their origin and history. Geologists use the of crystal size (microscopic vs. visible vs. glassy) as a primary means of whether an igneous rock is or in origin. Part II: Sedimentary Rocks (click on Sedimentary Rocks) Sedimentary rocks can form wherever sediments can. 1. List the areas where sediment can accumulate. 2. What is weathering and where does it occur?
Once rocks are weathered, carries the rock fragments (such as sand) and other chemical products (such as clays and dissolved ions) from the site of weathering to a site of, where the sediment can accumulate. of the sediments then creates the opportunity for, the process of turning sediments into rocks. They re Everywhere: Roughly of the earth's surface (and nearly 100% of the ocean floor) is by and rocks. However, sedimentary rocks make up a very small portion of the earth's crust by mass or volume (roughly 5-10%). Sedimentary rocks form a relatively thin layer covering the crust, usually less than a kilometer thick but as much as 12-15 km thick in sites of active deposition (such as the Amazon River delta in Brazil). Detrital and Chemical: 1. What is a detrital sedimentary rock? 2. What is a chemical sedimentary rock? History of the World: Sedimentary rocks also exhibit evidence of the ancient environments in which they were deposited. and -bedding provides information about types and directions of water or wind currents. can show that sediment was deposited in shallow water that dried up periodically. provide evidence of creatures that lived long ago and tell us that the environment could support their livelihood. Nearly all our knowledge of dinosaurs, of course, comes from sedimentary rocks. Weathering and Transport: 1. What is weathering? 2. What would happen if there was no weathering? 3. List the two types of weathering and describe each.
Break em: weathering uses brute force and cunning to tear apart rocks. A common is wedging, which occurs whenever water enters a crack in a rock and freezes - expansion of the ice wedges the rock apart farther, allowing water in even more during the next freeze-thaw cycle. elevations extremes of and climates contribute to strong mechanical weathering processes. Glaciers, landslides, and rushing mountain streams help carry the broken rock clasts downhill. Mechanical weathering is the source of much detrital sediment that is transported to the sea in our rivers, especially gravel and sand. Dissolve em: Chemical weathering involves chemical reactions between and the of the rock. Chemical weathering is in moist, because these chemical reactions take place more quickly in hot, wet conditions. Living, such as plants and soil microorganisms, also the rate of weathering. Thus tropical rainforests are very effective environments for chemical weathering (hot, humid, lots of biological activity). Chemical weathering can some rocks, such as, almost completely, and the water that dissolved these rocks carries away all the ions (charged atoms) invisibly, in solution. (common in soils and elsewhere) is a family of minerals that is only chemical processes. Move em out: From the moment that sediment is generated by weathering, pulls it downhill. may be great distances as it moves downhill. For instance, sediments that are formed on the east side of the Rocky Mountains make it all the way to the Gulf of Mexico before they come to rest. Wind may also help to transport sediment (think deserts and dust storms). Chemical sediment (as ions) is transported with the water in which it is dissolved, usually to the sea or large lakes. Here, the ions can be precipitated and form new sediment in the form of a seashell or some other type of chemical sediment. All sediment may experience further changes as it is transported, such as rounding of grain edges and breaking down into even smaller grains as it works its way toward a final resting place to become a small part of a rock. Deposition and Lithification: 1. Where does deposition occur? 2. Why do streams flow very fast around mountains? 3. Describe what happens to sediment size as it transported from a mountain area to sea level (give a detailed answer). Use pictures to help with your explanation.
More Deposits: 1. Where do glaciers deposit their sediment load? 2. How do wind currents deposit their sediment load? 3. What happens to material in landslides? 4. Where does sediment for rock salt and limestone come from? 5. Where are salts deposited? 6. How is the sediment in limestone made? Burial: 1. Describe what happens when burial occurs. Lithification: 1. What does lithification mean? 2. Describe compaction and cementation.
Part III: Metamorphic Rocks (click on Metamorphic Rocks) 1. When does metamorphism occur? Two Examples: 1. Describe the differences between Phyllite and Gneiss. Heat and Pressure: 1. Where does the heat and pressure come from? Draw the diagram on the screen. Include everything in the picture.
Describe several types of metamorphic environments: 1) High temperature, High pressure: 2) High temperature, Low pressure: 3) Low temperature, High pressure: 4) Hot water, Low pressure: