Fire and Ice. Overview. Grade Level 6 8. Students will be able to: Objectives

Transcription

1 Fire and Ice Overview Students use a power point presentation to compare and contrast the geologic history and environment of Mount Rainier and Mount Fuji, the Sister Mountains. Grade Level 6 8 Students will be able to: Objectives Compare and contrast Mount Rainier and Mount Fuji using a graphic organizer based on pictures and the processes that build up and break them down. Setting Classroom Timeframe Materials Vocabulary Standards 2 to 3 50 minute class periods Power point presentation Graphic Organizer (3 options) Topographic map of Mount Rainier and Mount Fuji Field Observation and Rock pictures (andesite, granodiorite, breccias, pumice) Eruption timeline graphics of Mount Rainier and Mount Fuji Hazard map of Mount Rainier and Mount Fuji Conical, strato/composite volcano, andesite, hydrothermal alteration, tephra, pyroclastic, Plinian eruption, Ring of Fire Science 6 8 INCQ Communicate results using pictures, tables, charts, diagrams, graphic displays and text that are clear, accurate and informative. 6 8 ES2F Describe what may happen when plate boundaries meet with examples from the Pacific Northwest. 6 8 ES2G Explain how a given landform has been shaped by processes that build up structures and by processes that break down and carry away material. Background Mount Rainier and Mount Fuji are volcanoes that formed along the Pacific Ring of Fire. This is a zone of plate tectonic and earthquake activity where subduction is the key. Subduction takes place at a boundary where two tectonic plates collide and one is forced underneath the other. The factor that causes a plate to be subducted is density. New plate material is being created at a divergent boundary, also known as a spreading ridge. The new plate material moves away from the ridge due to the formation of even newer plate material, which causes the plate to grow. As the plate is pushed farther from the spreading ridge and grows, it cools and compresses

2 due to overlying materials. The plate moves as it continues to grow and eventually encounters another plate. The denser of the two plates will be forced underneath the less dense plate. The denser plate is compressed even more as it is forced below and causes the water in the overlying materials on the plate to be squeezed out. This water mixes with the mantle material causing the melting of the overriding plate forming magma. The magma begins to rise through the plate above, melting the rock in that plate, adding to the total amount of magma, as it moves toward the surface. Once it reaches the surface, it flows out as lava and begins to build up into a volcano such Mount Rainier or Mount Fuji. If does not reach the surface, it cools into an intrusive rock called granodiorite. Though these mountains are formed in a similar way, the rocks found at each mountain are very different. Mount Rainier is composed of mostly andesite and Mount Fuji is composed of mostly basalt. Andesite is a fine grained extrusive igneous rock that partially cools before and/or during eruption which allows for the growth of crystals. Basalt is a fine grained extrusive igneous rock that cools after it is erupted, allowing for very little crystal growth. Though both are on subduction zones, Mount Fuji is different because there are four plates that are involved. The Pacific Plate is subducting beneath both the North American and Philippine Plates, while the Philippine Plate is subducting beneath the Eurasian Plate. The Philippine and Pacific Plates are both oceanic and providing the melting of rock for the magma chamber of Mount Fuji to erupt basalt. In contrast, the Juan de Fuca plate is an oceanic plate and is subducting below the North American Plate. It takes a longer time for the magma to move through the thicker continental North American Plate which allows time for the magma to cool more before erupting. The melting of oceanic plates tends to create basaltic magma, whereas the melting of an oceanic and a continental plate tends to have a more silica rich magma that produces andesitic and rhyolitic lavas. These beautiful mountains are strato/composite volcanoes. This type of volcano has a distinct conical or cone like shape which is due to the viscosity or fluidity of the lava. Viscosity is dependent upon the silica content of the lava; the higher the silica content, the higher the viscosity and the less fluid it is. This lava is thicker than the lavas you might see on the island of Hawaii where the silica content is lower, the viscosity is lower and the lava is more fluid. Mount Rainier s lava does not flow as far as the lavas on the island of Hawaii. Strato/composite volcanoes tend to have plinian eruptions. This type of eruption is violent and sends up a column of ash and tephra as well as a pyroclastic flow of hot ash and gases. Paired together, you get layers of lava, ash and tephra that build up the steep sides of the volcano, giving it a conical shape. Mount Rainier and Mount Fuji are called sisters for more than one reason; the obvious reason being that they are both volcanoes. However, if you look at them, they do not look the same. This is due to the process of erosion. Mount Rainier, from its birth, has been contending with the erosive power of ice. Glaciers have

3 been eroding down its summit and flanks for many years and caused it to lose its steep conical shape. Glaciers also provide the water for debris flows and lahars. A lahar is a debris flow that is large enough to move past the flanks of the mountain and inundate the valleys. In contrast, Mount Fuji must contend with the erosive power of wind, water and gravity. Its steep sides are scarred with landslide paths for which the wind and water take advantage of. Though it keeps its steep sided shape, it is no less vulnerable to erosion. Vocabulary: Subduction the process by which collision of the earth's crustal plates results in one plate's being drawn down or overridden by another Conical having the form of, resembling, or pertaining to a cone Strato/composite volcano a large, steep volcano built up of alternating layers of lava and ash or cinders Andesite a gray, fine grained volcanic rock, chiefly composed of plagioclase and feldspar Hydrothermal alteration hot water fluids pass through the rocks and changing their composition by adding or removing or redistributing components Tephra clastic volcanic material, such as scoria, dust, etc., ejected during an eruption Pyroclastic rock fragments of explosive origin, especially those associated with explosive volcanic eruptions Plinian eruption a volcanic eruption in which a stream of gas and ash is violently ejected to a height of several miles Ring of Fire an extensive zone of volcanic and seismic activity that coincides roughly with the borders of the Pacific Ocean Teacher Tips: The title of the lesson comes from the fact that both Mount Rainier and Mount Fuji were formed by fire, thus fire². Mount Rainier is also said to be formed by ice since there are many lava flow features on the mountain that reflect the lava being held back by ice. It is also being continually shaped by the one cubic mile of glacial ice that is present on the mountain today; thus ice³. You will see the following abbreviations in the power point: YA years ago

4 KYA thousand years ago MYA million years ago Procedure Suggested Assessment Adaptations Pass out a graphic organizer to students and have them write down facts for each mountain as you show the Fire² and Ice³ power point. Discuss each slide with students and have them complete the organizer by filling in the similarities section. 1. Grade graphic organizer. 2. Have students write a one paragraph summary based off of graphic organizer. Print power point slides and have students take notes. Use the topographic and hazard maps to compare the mountains based on elevation levels and hazards. Use the hazard maps and discuss the effects of the hazards on the surrounding cities, towns, rivers, etc. Use the field observation print outs to discuss the formation of the rocks found at the mountains using the pictures of the rocks. Use the Using the Earthquakes to find the subduction zone activity to graph the earthquakes on a graph and analyze the orientation of the subducting plate. Extensions For more detailed understanding of formation and geology of Mount Rainier and Mount Fuji, see the following lessons (sources in reference section): Mapping the Rim String of Volcanoes Cascade Volcano Timeline Fire and Ice Flood, Fire, and Fury References/ Resources Playdoh Topo Cascade Volcano Observatory. (1997). UW. Pacific northwest seismograph network Mt Rainer vicinity. USGS. Crandell, D. R. (1983). The geologic story of Mt Rainier. Geological Survey Bulletin National Parks and Forests Association. Dreiger, C. (2008). Personal communication

5 Ishii, Y.; Aramaki, S.; Miyaji, N.; Koyama, M. (2007). Cities on volcanoes 5 conference Shimabara, Japan field trip guide book (CD Rom). C4: Workshop and field excursion: Fuji volcano. Volcanological Society of Japan Tokyo, Japan. Sisson, T. and others (2001). Progress made in understanding Mount Rainier. EOS v. 82. p Takada, A.; Mannen, K.; Ukawa, M.; and Chiba, T. (2007). Cities on volcanoes 5 conference Shimabara, Japan field trip guide book (CD Rom). A3: Fuji and Hakone volcanoes. Volcanological Society of Japan Tokyo, Japan. Pringle, P. (2008). Roadside geology of Mt. Rainier and vicinity. Washington Division of Geology and Earth Resources Information Circular 107. Definitions Extension Lesson Websites (Mount Rainier versions): Driedger, C., Doherty, A., &Dixon, C. (2005) String of Volcanoes. Living with a volcano in your backyard an educator s guide with emphasis on Mt Rainier. General Information Driedger, C., Doherty, A., &Dixon, C. (2005) Cascade Volcano Timeline. Living with a volcano in your backyard an educator s guide with emphasis on Mt Rainier. General Information Driedger, C., Doherty, A., &Dixon, C. (2005) Fire and Ice. Living with a volcano in your backyard an educator s guide with emphasis on Mt Rainier. General Information Driedger, C., Doherty, A., &Dixon, C. (2005) Flood, Fire, and Fury. Living with a volcano in your backyard an educator s guide with emphasis on Mt Rainier. General Information Driedger, C., Doherty, A., &Dixon, C. (2005) Play dough Topo. Living with a volcano in your backyard an educator s guide with emphasis on Mt Rainier. General Information dough_topo.pdf