...1) Describe the bathymetry of the ocean seafloor and how the features relate to plate tectonics. The bathymetry of the ocean floor is the shape of the ocean floor. On the ocean floor there are also anomalies, gravity and magnetism in different areas of the ocean. “We know these things because it has been mapped out using a process called sonar, Sound Navigation and Ranging. This is done by creating sound waves from a ship at the surface that bounce down off of the seafloor and then come back up. There have actually been a variety of techniques. One of the most important has been side scan sonar that is actually able to map to fine details of the shapes of the ocean seafloor.” (Wysession, teachingcompany.12.forumer.com; 2008) “Ocean bathymetry, to the people involved with early mapping, was a total surprise for a wide variety of reasons.” (Wysession, teachingcompany.12.forumer.com; 2008) “When you look at a lake you know that the deepest parts of that lake will be out away from the shore, perhaps on the very middle. The areas around the back are usually the shallowest. This is not the case in the ocean. In the ocean, the deepest places are the ocean trenches which are found at the edges of continents. It turned out that in the middle of the ocean there are mid-ocean ridges that formed this long continuous chains of mountains that are all connected. The mid-Atlantic ridge connects to the east Pacific rise, and the Indian ridge, and in all three principle oceans these represent...
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...Written Assignment 3 1. Describe the bathymetry of the ocean seafloor and how the features relate to plate tectonics. The term “bathymetry” originally referred to the ocean’s depth relative to sea level, although it has come to mean “submarine topography,” or the depths and shapes of underwater terrain. In the same way that topographic maps represent the three-dimensional features of overland terrain, bathymetric maps illustrate the land that lies underwater. The ocean has mountain ranges, volcanoes, trenches, canyons, and other structures. The oldest rocks on the ocean floor are 180 million years old. This is young compared with the oldest continental rocks, which date from 3.8 billion years ago. While the continental crust has been steadily accumulating throughout Earth’s history, it seems the oceanic crust is created and destroyed rather quickly. It is created at the mid-ocean ridges from hot material rising in the mantle, and then spreads away from the ridges, before eventually being recycled into the mantle at subduction zones. Continental crust is always less dense and more buoyant than oceanic crust, so where they meet, it is the oceanic crust that gives way, sinking (subducting) back into the mantle The boundaries of a tectonic plate may be divergent, convergent, or transform. At divergent boundaries, the crust is extended, thinned, and fractured by the upwelling of hot mantle material. The crust buoys up, producing a mid-ocean ridge, and lava is extruded through a...
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...Francis Bacon spotted that the west coast of Africa and the east coast of South America looked as if they would fit together, like pieces of a jigsaw puzzle. Between then and 1912 other people identified further similarities between other continental coastlines. Robert Mallet 1870s Robert Mallet was a nineteenth century scientist who managed to measure the speed at which earthquakes spread. Alfred Wegner 1911 While at Marburg, in the autumn of 1911, Wegener was browsing in the university library when he came across a scientific paper that listed fossils of identical plants and animals found on opposite sides of the Atlantic. Intrigued by this information, Wegener began to look for, and find, more cases of similar organisms separated by great oceans. Orthodox science at the time explained such cases by postulating that land bridges, now sunken, had once connected far-flung continents. But Wegener noticed the close fit between the coastlines of Africa and South America. Might the similarities among organisms be due, not to land bridges, but to the continents having been joined together at one time? As he later wrote: "A conviction of the fundamental soundness of the idea took root in my mind." Such an insight, to be accepted, would require large amounts of supporting evidence. Wegener found that large-scale geological features on separated continents often matched very closely when...
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...Intergovernmental Oceanographic Commission Manuals and Guides 52 Intergovernmental Oceanographic Commission TSUNAMI RISK ASSESSMENT ANDMITIGATION FOR THE INDIAN OCEAN KNOWING YOUR TSUNAMI RISK – AND WHAT TO DO ABOUT IT June 2009 UNESCO 1 Intergovernmental Oceanographic Commission Manuals and Guides 52 knowing your tsunami risk – and what to do about it Tsunami risk assessment and mitigation for the Indian Ocean; The designation employed and the presentation of material throughout the publication do not imply the expression of any opinion whatsoever on the part of UNESCO in particular concerning the legal status of any country, territory, city or area or of its authorities, or the delineation of its frontiers or boundaries. The authors are responsible for the choice and the presentation of the facts contained in this manual and for the opinions expressed therein, which are not necessarily those of UNESCO and do not commit the Organization. Designer: Eric Loddé For bibliographic purposes, this document should be cited as follows: Tsunami risk assessment and mitigation for the Indian Ocean; knowing your tsunami risk – and what to do about it IOC Manual and Guides No. 52, Paris: UNESCO, 2007 (English). Printed by UNESCO (IOC/2009/MG/52) © UNESCO IOC 2009 Tsunami risk assessment and mitigation for the Indian Ocean; knowing your tsunami risk – and what to do about it 3 Table of contents Acknowledgement .........................................................
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