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Geologic Features Identification and Summary Activity Name: Teacher Key Directions: Each visual aid represents a geologic feature found on Earth. 1. Choose three slips of paper at random that correspond to the number of feature. 2. Identify the type of feature by name. Look for clues in the picture to help you decide what the item is showing. 3. Describe how this feature has come into existence on Earth. You may use resources to help you summarize the process by which this feature has come into its present form. Examples of resources can include your textbook, library books, online resources approved by the teacher. Record your findings on this worksheet. 4. Check the answer key to compare your answers to the actual names. Feature #1: Type of feature: Canyon: Lodore Canyon and Green River, Utah Description of how this feature came to its present form: From Dictionary.com: A narrow chasm with steep cliff walls, cut into the earth by running water; a gorge. Feature #2: Type of feature: Waterfall: Shoshone Falls, Idaho Description of how this feature came to its present form: From: http://www.worldworx.tv/global-information/waterfalls/index.htm Waterfalls are created by water flows, often from rivers that run over the edges of steep cliffs or rugged features like plateaus. Occasionally a waterfall will appear as a result of earthquake activity where valleys become deeper, increasing river flows. Melting glaciers also create beautiful waterfalls in polar regions. Glaciers grind rock formations over time and when they finally melt, valleys have often been carved away, allowing for more waterflow and eventually creating a waterfall that may now flow over a valley's edge, into a pool below. Parts of Norway and the Alps become glacier regions in wintertime, melting in spring to create new waterfall formations. As more and more water pounds into the waterfall's pool beneath it, rocks become eroded away and eventually the rock face the waterfall cascades over will collapse. The new mass of water shunts downstream and may create a brand new waterfall. Waterfalls may travel several kilometers upstream when such a process occurs. Feature #3: Type of feature: Volcano: W.A. Hesse taking moving pictures of Katmai Volcano Description of how this feature came to its present form: From: http://volcano.und.edu/vwdocs/frequent_questions/grp12/question4252.html Volcanoes are formed from layers of lava and/or ash. Depending on whether they are explosive volcanoes (mostly ash) or non-explosive ones (mostly lava) or something in between, they build just by piling on the layers over time. Feature #4: Type of feature: Glacier: Asulkan Glacier from glacier crest, Selkirk Mts., B.C. Description of how this feature came to its present form: From: http://nsidc.org/glaciers/story/grow.html A glacier forms when snow accumulates over time, turns to ice, and begins to flow outwards and downwards under the pressure of its own weight. In polar and high-altitude alpine regions, glaciers generally accumulate more snow in the winter than they lose in the summer from melting, ablation, or calving. If the accumulated snow survives one melt season, it is considered to be firn. The snow and firn are compressed by the overlying snow, and the buried layers slowly grow together to form a thickened mass of ice. The pressure created from the overlying snow compacts the underlying layers, and the snow grains become larger ice crystals randomly oriented in connected air spaces. These ice crystals can eventually grow to become several centimeters in diameter. As compression continues and the ice crystals grow, the air spaces in the layers decrease, becoming small and isolated. This dense glacial ice usually looks somewhat blue. Feature #5: Type of feature: Beach: Theodor Horydczak and family. Fritzie Horydczak and Norma at the beach Description of how this feature came to its present form: From: http://coastalchange.ucsd.edu/st3_basics/beaches.html How do beaches form? Beaches consist of the coarse erosion products of the land (sand and pebbles) and sea (shell and coral fragments). Waves and currents sort the sediment and move it alongshore as a river of sand, predominantly to the south along the California coast. Coarser material remains closer to shore. Below mobile surface sediments, a bedrock platform slopes gently seaward and serves as a foundation for the beach. Feature #6: Type of feature: Earthquake: Palestine events. The earthquake of July 11, 1927. Deep fissures or land openings near the Dead Sea, caused by the earthquake. From: http://en.wikipedia.org/wiki/Earthquake Description of how this feature came to its present form: An earthquake is a sudden and sometimes catastrophic movement of a part of the Earth's crust. Earthquakes result from the dynamic release of elastic strain energy that radiates seismic waves. Earthquakes typically result from the movement of faults, planar zones of deformation within the Earth's upper crust. The word earthquake is also widely used to indicate the source region itself. The Earth's lithosphere is a patch work of plates in slow but constant motion (see plate tectonics). Earthquakes occur where the stress resulting from the differential motion of these plates exceeds the strength of the crust. The highest stress (and possible weakest zones) are most often found at the boundaries of the tectonic plates and hence these locations are where the majority of earthquakes occur. Events located at plate boundaries are called interplate earthquakes; the less frequent events that occur in the interior of the lithospheric plates are called intraplate earthquakes (see, for example, New Madrid Seismic Zone). Earthquakes related to plate tectonics are called tectonic earthquakes. Most earthquakes are tectonic, but they also occur in volcanic regions and as the result of a number of anthropogenic sources, such as reservoir induced seismicity, mining and the removal or injection of fluids into the crust. Seismic waves including some strong enough to be felt by humans can also be caused by explosions (chemical or nuclear), landslides, and collapse of old mine shafts, though these sources are not strictly earthquakes. These sources will also show a different seismogram than earthquakes. Feature #7: Type of feature: Earthquake: Earthquake damage Description of how this feature came to its present form: See information on Feature #6. Feature #8: Type of feature: Island: Map of the Hawaiian Islands. Description of how this feature came to its present form: From: http://www.enviroliteracy.org/article.php/274.html Islands support varied and unique ecosystems throughout the world. Islands range in size from small atolls only a few meters in elevation to the steep and varied topography of volcanic and mountainous islands. Islands form in various ways. Volcanic islands are formed when undersea volcanos erupt and layers of cooled lava emerge above the surface of the ocean. The Hawaiian islands, for example, are volcanic islands. Other islands are formed when ocean waters rise, separating a section of land from the mainland, or when a piece of a continent breaks off from the mainland. Madagascar, which is the world's fourth largest island, formed in this way. Islands also can be formed when a coral reef emerges above the surface and sand and dust carried by wind and water accumulate over time, forming an island. The Florida Keys are examples of coral reef islands. Barrier islands are formed by the action of wind, water, and tides, which shape sand into islands along coastlines. Feature #9: Mountain: Summit of Pikes Peak Description of how this feature came to its present form: From: http://yahooligans.yahoo.com/content/ask_earl/page?d=20010306 The Earth's outer crust, or lithosphere, is made up of seven huge chunks of land called plates. These plates actually move around--they travel at about the same speed that your fingernails grow. Where these plates bump into each other, mountain ranges form. The Earth is constantly churning, shifting, pulling apart, and pushing together. The study of how these plates shift around is called Plate Tectonics. Other mountains form when rain and wind break down softer rock and leave hard rock formations still standing. Feature #10: Devil’s Slide, Utah (Erosion of less resistant rock, leaving more resistant rock behind) Description of how this feature came to its present form: From: http://geology.utah.gov/surveynotes/geosights/devilsslide.htm Devils Slide is a classic example of how different rock layers, depending on their composition, are affected by weathering and erosion. The sides of the slide are hard, weather-resistant limestone layers about 40 feet high, 25 feet apart, and several hundred feet in length. In between these two hard layers is a shaly limestone that is slightly different in composition from the outer limestone layers. This middle layer is softer, which makes it more susceptible to weathering and erosion, thus forming the chute of the slide. Looking like a large playground slide fit only for the Devil, this site is a tilted remnant of sediments deposited in a sea that occupied Utah’s distant geologic past. Approximately 170 to 180 million years ago, a shallow sea originating from the north spread south and east over areas of what are now Montana, Wyoming, and Utah. This sea extended as far east as the present-day Colorado River and south into northern Arizona. Over millions of years, massive amounts of sediment accumulated and eventually formed layers of limestone and sandstone. In northern Utah, these rocks are known as the Twin Creek Formation and are approximately 2700 feet thick. About 75 million years ago, folding and faulting during a mountain- building episode tilted the Twin Creek rock layers to a near-vertical position. Subsequent erosion has exposed the near-vertical rock layers and created Devils Slide. Feature #11: Eroded rocks monument park. Description of how this feature came to its present form: Example of less resistant rock having eroded away leaving behind the more resistant rock formation.