submarine‚ forming new seafloor. Black smokers or deep sea vents are an example of this kind of volcanic activity. Where the mid-oceanic ridge is above sea-level‚ volcanic islands are formed‚ for example‚ Iceland. Convergent plate boundaries: Subduction zones are places where two plates‚ usually an oceanic plate and a continental plate‚ collide. In this case‚ the oceanic plate subducts‚ or submerges under the continental plate forming a deep ocean trench just offshore. In a process called flux
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growing of the North American basement rock and the formation of super continent Columbia. This can be seen because the Idaho Springs gneiss was formed deep underground and deep in oceans‚ and was only brought up to the surface through erosion and subduction zones. An analog to this rock structure is the Sea of Japan in current
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Mount Saint Helen’s Volcano‚ part of the cascade mount range‚ is associated with the subduction zone of the Juan du Fuca plate into the North American plate‚ as is most of the volcanism in this mount range (USGS Geology & History). The eruption intensity is normally quite explosive but Mt. Saint Hellen’s has experienced the peaceful one on occasion (USGS Geology & History). With frequent eruption every couple hundred years (rough estimate at best)‚ Mt. Saint Helen’s is the most active volcano of
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Archeozoic Era The Archeozoic Era stretches from about 3.8 billion to 2.5 billion years ago. Traditionally‚ the beginning of the Archean is defined to coincide with the oldest rocks discovered. As recent discoveries have pushed back the earliest dated rocks to about 4.0 billion years old‚ the beginning of the Archean has also been pushed back correspondingly. However‚ most texts still continue to date the beginning to 3.8 billion years ago. As the Late Heavy Bombardment (LHB) ended with the Hadean
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not overly violent since the divergent plates are typically underwater. For this reason‚ the magma forms new oceanic crust in its eruption. Deep-sea trenches are a notorious bathymetric feature of convergent plate boundaries which often form at subduction zones‚ where one converging plate is moving beneath the other‚ hence their deep nature. As this plate descends further into the mantle‚ magma rises and partially melts the overlapping mantle; this may lead to a violent eruption which will come to
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Lecture 1: Introduction Geology - the study of the Earth‚ the processes that shape it‚ and the resources that could be obtained from it. Main branches Physical Geology - deals with the materials that comprise the Earth and the processes that affect it (e.g.‚ Volcanology‚ Seismology‚ Environmental Geology‚ Engineering Geology‚ Mining Geology‚ Petroleum Geology‚ Mineralogy‚ Petrology‚ Geomorphology‚ Geophysics‚ Geochemistry‚ Planetary Geology) Historical Geology - the study of the origin and
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coast‚ with large fraction of surface area in water‚ little in marshes; usually shallow (2m depth); wind dominated water mixing; often behind a sand barrier or a coral barrier reed formed during interglacial 80‚000 years ago. Fjord – occurs along subduction zones. Formed by glaciers moving seaward‚ then retreating; a rock bar (sill) is left at the mouth of fjord; as glaciers push rocks down toward the sea‚ they left a rock pike at mouth as they floated in the sail water. Also‚ a u-shaped cross-section;
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does the density of Earth’s composition change as you get closer to the core? a. The density of Earth materials increases as the core is approached. 5. What is the mechanism by which lithospheric plates move? a. Seafloor spreading 6. What is a subduction zone? a. oceanic trench site of crust destruction 7. How are magnetic stripes on the seafloor created? 8. What are the 3 types of plate boundaries? a. Divergent b. Convergent c. Major transform 9. Describe the 3 types of plate boundaries
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would birth mountain building. It is a theory that Europe and Asia collided millions of years ago. Marine life would have existed in the ocean basin between the land masses. As the continents approached‚ waters would recede from between them through subduction. This is caused by a later displacement of large blocks of the Asian crust by the mechanism continental escape. This developed the compressional mountains that led to the creation of the Urals. In addition to the creation of the mountains‚ the
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Professor FitzGerald Spring 2011 Introduction to Beaches and Shorelines ES 142 Exam #1 Study Questions SUBJECT: Plate Tectonics 1. What occurs at subduction zones? Draw a cross section of oceanic plate subducting beneath a continental plate (Nazca beneath South America). 2. What is the lithosphere and what are the major lithospheric plates? 3. What are the various features and processes that
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