DOCSLIB.ORG

Conservation of Arctic Marine Mammals Faced with Climate Change Author(S): Timothy J

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Conservation of Arctic Marine Mammals Faced with Climate Change Author(S): Timothy J Conservation of Arctic Marine Mammals Faced with Climate Change Author(s): Timothy J. Ragen, Henry P. Huntington and Grete K. Hovelsrud Source: Ecological Applications, Vol. 18, No. 2, Supplement: Arctic Marine Mammals and Climate Change (Mar., 2008), pp. S166-S174 Published by: Wiley on behalf of the Ecological Society of America Stable URL: http://www.jstor.org/stable/40062164 Accessed: 04-04-2017 17:09 UTC JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact [email protected]. Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at http://about.jstor.org/terms Wiley, Ecological Society of America are collaborating with JSTOR to digitize, preserve and extend access to Ecological Applications This content downloaded from 199.8.170.13 on Tue, 04 Apr 2017 17:09:29 UTC All use subject to http://about.jstor.org/terms Ecological Applications, 18(2) Supplement, 2008, pp. S166-S174 © 2008 by the Ecological Society of America CONSERVATION OF ARCTIC MARINE MAMMALS FACED WITH CLIMATE CHANGE Timothy J. Ragen,1'4 Henry P. Huntington,2 and Grete K. Hovelsrud3 ]U.S. Marine Mammal Commission, 4340 East- West Highway, Room 905, Bethesda, Maryland 20814 USA 2Huntington Consulting, 23834 The Clearing Drive, Eagle River, Alaska 99577 USA 3 Cent re for International Climate and Environmental Research - Oslo (CICERO), P.O. Box 1129, Blindern N-0318 Oslo, Norway Abstract. On a daily basis, societies are making decisions that will influence the effects of climate change for decades or even centuries to come. To promote informed management of the associated risks, we review available conservation measures for Arctic marine mammals, a group that includes some of the most charismatic species on earth. The majority of available conservation measures (e.g., restrictions on hunting, protection of essential habitat areas from development, reduction of incidental take) are intended to address the effects of increasing human activity in the Arctic that are likely to follow decreasing sea ice and rising temperatures. As important as those measures will be in the effort to conserve Arctic marine mammals and ecosystems, they will not address the primary physicalmanifestations of climate change, such as loss of sea ice. Short of actions to prevent climate change, there are no known conservation measures that can be used to ensure the long-term persistence of these species and ecosystems as we know them today. Key words: Arctic; climate change; conservation; marine mammals; risk analysis. Introduction The papers in this Special Issue examine the ongoing Anthropogenic climate change, perhaps more and than potential physical effects of climate change in the any other consequence of human civilization, hascoming the century and their likely impacts on Arctic potential to change Arctic ecosystems profoundly. marine mammals. In this paper, we consider a range Temperatures and sea levels are rising and will of lead conservation to measures to address those impacts. By "conservation measures" we mean actions that can be coastal and insular inundation (McCarthy et al. 2001). Important Arctic habitat, most notably sea ice (Parkin- taken to prevent, minimize, or mitigate human impacts son et al. 1999), will be altered or destroyed, oncausing Arctic ecosystem components and processes, thereby extensive redistribution of mobile species, the perpetuating disap- the natural ecology and evolution of these pearance of nonmobile species throughout portions ecosystems. of The term "prevention" may not be strictly their range, and possible species extinction (Thomas accurate, et inasmuch as climate change is underway and al. 2004). Climate change will involve alteration ofcan water no longer be prevented fully. Although "minimiza- and nutrient cycles and energy pathways in the tion"world's might be a more accurate term, we use "preven- oceans (Macdonald et al. 2005). It may alter oceanic tion" andbecause it connotes a stronger, more effective, and, atmospheric circulation patterns (Schmittner 2005), to thewith extent possible, more proactive management potentially severe biological and ecological consequenc- approach. es for many, if not all, ecosystems, marine Whether and mindful of it or not, societies already are terrestrial. Through physical, chemical, and biological conducting a de facto risk analysis on climate change linkages, these changes will cascade through ecosystems. and its potential consequences. In this paper we use a The unexpectedly rapid disintegration of the Larsenrisk analysis B framework (Maguire 1991, Harwood 2000) ice shelf in the Antarctic (Shepherd et al. 2003), to consider the potential conservation measures to address surprisingly rapid pace of glacial decline on Greenland those risks. By taking this approach, we hope to make (Rignot and Kanagaratnam 2006), and other recent, the analysis clearer and more useful for managing the unanticipated observations suggest we are in for human a great activities that contribute to climate change or many surprises with respect to the regional and exacerbate global climate change effects. effects of climate change. The end result may be beyond The first steps in such an analysis are identification of our ability to predict or imagine. the physical causes and manifestations of climate change and description of the hazards to which marine mammals may be exposed. Preceding papers in this Manuscript received 4 May 2006; accepted 19 June 2006; volume provide such information, and we review them final version received 19 September 2006. Corresponding Editor: P. K. Dayton. For reprints of this Special Issue, see only briefly here. A range of natural factors contribute footnote 1, p. SI. to climate change, including variations in energy output 4 E-mail: tragen(a) mmc.gov from the sun, variations in the geometric relationship S166 This content downloaded from 199.8.170.13 on Tue, 04 Apr 2017 17:09:29 UTC All use subject to http://about.jstor.org/terms March 2008 ARCTIC MARINE MAMMALS AND CLIMATE CHANGE S167 between the sun and the earth, terms volcanic and come eruptions, to grips with and the discipline and continental drift. Human activities contribute to climate constraints they require. Thus, they can easily become change primarily through their influence on the earth's more a facade than a true standard against which we atmosphere. Emissions of carbon dioxide, methane, and measure our impacts. Before considering the potential other greenhouse gases appear to be the most important risks from climate change and deciding how best to anthropogenic drivers of climate change, and much ofrespond to them, it is important to determine both the the discussion regarding prevention measures has tolerance of Arctic ecosystems for climate change effects focused on controlling such emissions. (i.e., inherent ability to withstand perturbation), as well The major physical manifestations of climate change as our (society's) tolerance for Arctic degradation (i.e., in the Arctic marine environment (ACIA 2004, Walsh subjective human sensitivity to environmental loss). 2008) include changes in temperature, sea ice, terrestrial Although science can estimate the risk and resilience ice (including permafrost), precipitation, freshwater of species and ecosystem processes to changes in climatic flow, sea level, sea surface and water column tempera- conditions, society's perception of the risks and its tures, and oceanic and atmospheric circulation. willingness to accept a given level of environmental The biological and ecological consequences of climate disturbance are more difficult to quantify. Determining change will vary depending on the species involved. Asthose limits is vital because they will shape the standards in other papers in this volume, we focus our discussion and measures used to guide and influence Arctic of "Arctic" marine mammals (i.e., those occurring in the conservation in the face of climate change. Arctic year-round) on polar bear (Ursus maritimus), Determining "safe" thresholds for human activities walrus (Odobenus rosmarus), ringed seal (Phoca hispida), and impacts in the Arctic and elsewhere is made difficult bearded seal (Erignathus barbatus), beluga whale (De- by the considerable uncertainty about what constitutes a phinapterus leucas), narwhal (Monodon monoceros), and healthy ecosystem and how much disturbance different bowhead whale {Balaena mysticetus) species. Other ecosystems can withstand before basic functions are lost species that inhabit the Arctic at least seasonally include or unacceptably diminished. The uncertainty stems in ribbon seals {Histrio phoca fasciata), spotted seals part from the complexity of ecosystems and the (Phoca larghd), harp seals (Phoca groenlandica), hooded difficulty in understanding their physical, chemical, seals (Cystophora cristata), gray whales (Eschrichtius and biological elements and natural dynamics. The robustus), killer whales (Orcinus orca), minke whales uncertainty is further confounded by the addition of (Balaenoptera acutorostrata), fin whales (Balaenoptera human activities that may alter ecosystem composition physalus), and humpback whales (Megaptera novaean- and dynamics before sufficient baseline information has gliae). been collected to provide a basis
Load more

Recommended publications
  • Dolerites of Svalbard, North-West Barents Sea Shelf: Age, Tectonic Setting and Significance for Geotectonic Interpretation of Th
    RESEARCH/REVIEW ARTICLE Dolerites of Svalbard, north-west Barents Sea Shelf: age, tectonic setting and significance for geotectonic interpretation of the High-Arctic Large Igneous Province Krzysztof Nejbert1, Krzysztof P. Krajewski2, Elz˙bieta Dubin´ ska1 & Zolta´ nPe´ cskay3 1 Institute of Geochemistry, Mineralogy and Petrology, University of Warsaw, Al. Z˙ wirki i Wigury 93, PL-02089 Warsaw, Poland 2 Institute of Geological Sciences, Polish Academy of Sciences, Research Centre in Warsaw, ul. Twarda 51/55, PL-00818 Warsaw, Poland 3 Institute of Nuclear Research, Hungarian Academy of Sciences, Bem te´ r 18/c, HU-4026 Debrecen, Hungary Keywords Abstract Dolerite; geochemistry; petrogenesis; KÁAr whole rock ages; Svalbard; Cretaceous. The dolerites of Svalbard are mineralogically and geochemically homogeneous with geochemical features typical of continental within-plate tholeiites. Their Correspondence geochemistry is similar to tholeiites belonging to a bimodal suite defined as the Krzysztof P. Krajewski, Institute of Geologi- High-Arctic Large Igneous Province (HALIP). KÁAr dating of numerous cal Sciences, Polish Academy of Sciences, dolerites sampled from many locations across Svalbard define a narrow time Research Centre in Warsaw, ul. Twarda 51/ span of this magmatism from 125.593.6 to 78.392.6 Mya. Discrete peaks of 55, PL-00818 Warsaw, Poland. E-mail: [email protected] intensive activity occurred at 115.3, 100.8, 91.3 and 78.5 Mya corresponding to (1) breakup of the continental crust and formation of an initial rift as a result of mantle plume activity, located in the southern part of the Alpha Ridge; (2) magmatic activity related to spreading along the Alpha Ridge that led to the development of the initial oceanic crust and (3) continuation of spreading along the Alpha Ridge and termination of magmatic activity related to HALIP (last two peaks at 91.3 and 78.5 Mya).
    [Show full text]
  • General Guide to the Science and Cosmos Museum
    General guide to the Science and Cosmos Museum 1 Background: “Tenerife monts” and “Pico” near of Plato crater in the Moon PLANTA TERRAZA Terrace Floor 5 i 2 1 4 6 3 ASCENSOR 4 RELOJ DE SOL ECUATORIAL Elevator Analemmatic sundial i INFORMACIÓN 5 BUSTO PARLANTE Information “AGUSTÍN DE BETANCOURT” Agustín de Betancourt 1 PLAZA “AGUSTÍN DE talking bust BETANCOURT” Agustín de Betancourt 6 ZONA WI-FI Square Wi-Fi zone 2 ANTENA DE RADIOASTRONOMÍA Radioastronomy antenna 3 TELESCOPIO Telescope PLANTA BAJA Ground Floor WC 10 9 8 11 7 1 6 5 4 12 2 3 ASCENSOR Cosmos Lab - Creative Elevator Laboratory 1 EXPOSICIÓN 7 PLANETARIO Exhibition Planetarium 2 TALLER DE DIDÁCTICA 8 SALIDA DE EMERGENCIA Didactic Workshop Emergency exit 3 EFECTOS ÓPTICOS 9 MICROCOSMOS Optical illusions 10 SALÓN DE ACTOS 4 SALA CROMA KEY Assembly hall Chroma Key room 11 EXPOSICIONES TEMPORALES 5 LABERINTO DE ESPEJOS Temporary exhibitions Mirror Labyrinth 12 ZONA DE DESCANSO 6 COSMOS LAB - LABORATORIO Rest zone CREATIVO CONTENIDOS Contents 7 LA TIERRA The Earth 23 EL SOL The Sun 33 EL UNIVERSO The Universe 45 CÓMO FUNCIONA How does it work 72 EL CUERPO HUMANO The human body 5 ¿POR QUÉ PIRÁMIDES? Why pyramids? 1 Sacred places have often been con- ceived of as elevated spaces that draw the believer closer to the divi- nity. For this reason, once architec- tural techniques became sufficiently refined, mosques or cathedrals rai- sed their vaults, minarets, towers and spires to the sky. However, for thousands of years, the formula fa- voured by almost every culture was the pyramid.
    [Show full text]
  • A Christian Physicist Examines Noah's Flood and Plate Tectonics
    A Christian Physicist Examines Noah’s Flood and Plate Tectonics by Steven Ball, Ph.D. September 2003 Dedication I dedicate this work to my friend and colleague Rodric White-Stevens, who delighted in discussing with me the geologic wonders of the Earth and their relevance to Biblical faith. Cover picture courtesy of the U.S. Geological Survey, copyright free 1 Introduction It seems that no subject stirs the passions of those intending to defend biblical truth more than Noah’s Flood. It is perhaps the one biblical account that appears to conflict with modern science more than any other. Many aspiring Christian apologists have chosen to use this account as a litmus test of whether one accepts the Bible or modern science as true. Before we examine this together, let me clarify that I accept the account of Noah’s Flood as completely true, just as I do the entirety of the Bible. The Bible demonstrates itself to be reliable and remarkably consistent, having numerous interesting participants in various stories through which is interwoven a continuous theme of God’s plan for man’s redemption. Noah’s Flood is one of those stories, revealing to us both God’s judgment of sin and God’s over-riding grace and mercy. It remains a timeless account, for it has much to teach us about a God who never changes. It is one of the most popular Bible stories for children, and the truth be known, for us adults as well. It is rather unfortunate that many dismiss the account as mythical, simply because it seems to be at odds with a scientific view of the earth.
    [Show full text]
  • Wegener and His Theory of Continental Drift
    GENERAL I ARTICLE Wegener and his Theory of Continental Drift Ramesh Chander Alfred Wegener, an astronomer by training and meteorologist by profession, visualised that there was once a single very large landmass on the surface of the earth. Gradually it broke up into smaller fragments which drifted away to form the present continents. In a few cases, the drifting fragments subsequently collided, coalesced and Ramesh Chander is a formed larger landmasses again. Wegener could thus Professor at the Universit}' explain in a simple way (i) similarities in shapes of of Rool'kee, engaged in diverse studies related to continental coast lines separated by wide oceans, (ii) natural earthquakes in the similarities in the rocks and fossils occurring on such Himalaya as well as coasts and in the fauna and flora inhabiting them, (ill) the modelling of reservoir­ formation of several major mountain ranges of the world, induced earthquakes in that region. and (iv) the evidence in rocks on past climates ofthe earth. Introduction Astronomers take immense delight in enumerating the various motions that we partake even as we are apparently stationary on the surface of the earth. Geophysicists, the people who apply the principles of physics to investigate the earth, gleefully add that the surface of the terra firma itself is not steady but responds pliantly to many causes in the earth's interior and on its surface as well as to a few causes in the solar system. Occasionally, we can feel the motion of the earth's surface directly for brief periods, as during a major earthquake or when a heavy object moves near us.
    [Show full text]
  • Planetarium Handbook
    Portable Planetarium Handbook Susan Reynolds Button, Editor July 2002 Table of Contents Section I. Table of Contents .................................................................................... 1 Section II. Introduction ............................................................................................. 1 Section III. Contributors............................................................................................. 1 Section IV. Practical Applications of Portable Planetariums...................................1 A. Introduction: “Why are Portable Planetariums so Special?” .......................2 1. “Twenty Years on the Road: The Portable Planetarium’s Development and Contributions to the Teaching of Astronomy” ......................................................................................3 2. “Outreach: The Long Arm of STARLAB”.......................................18 3. “Professionalism and Survival Tactics” ..........................................20 B. Outreach with a Planetarium Specialist ....................................................22 1. “Reach Out and Teach Someone” ................................................ 23 2. “Student Intern/Mentor Program Proposal”................................... 26 3. “Student-Directed Planetarium Lessons and Other Creative Uses For STARLAB”..................................................................... 27 C. Outreach-Lending/Rental Programs and Teacher Training ..................... 30 1. “Unmanned Satellite” ...................................................................
    [Show full text]
  • The Tertiary Orogenic Belt of West-Spitsbergen: Seismic Expressions of the Offshore Sedimentary Basins
    The Tertiary orogenic belt of West-Spitsbergen: Seismic expressions of the offshore sedimentary basins OLA EIKEN & ATLE AUSTEGARD Eiken, O. & Austegard, A.: The Tertiary orogenic belt of West-Spitsbergen: Seismic expressions of the offshore sedimentary basins. Norsk Geologisk Tidsskrift, Vol. 67, pp. 383-394. Oslo 1987. ISSN 0029- 196X. Sedimentary basins west of the exposed part of the West-Spitsbergen orogenic belt have been outlined by seismic reflection data. Narrow, fault-bounded grabens are infilled from both sides, with syn­ sedimentary movement and weak compression of the whole sequence. The grabens are probably all of Tertiary age. Sediment thicknesses are up to 4 km and widths are up to 15-20km. The main graben starts in the north with the Forlandsundet graben and is offset outside Isfjorden and possibly south of Bellsund. We are not able to discriminate between an extensional and a strike-slip model of graben-formation. Based on lateral velocity variations and thickness of post-rift sediments on the outer shelf and slope west of Spitsbergen, we assume 1-2 km of Tertiary sediments have been eroded from the offshore basins and 3 km in central Spitsbergen. Ola Eiken, Atle Austegard, Seismological Observatory, University of Bergen, Allegt. 41, 5000 Bergen, Norway. Svalbard is located at the northwestern corner of inner part of the shelf. Schluter & Hinz (1978) the Eurasian plate. A young (Tertiary) fold belt indicate vaguely some faulting inside the exists along its western margin (Fig. 1). Con­ Hornsund Lineament, but Myhre (1984) shows tinuation of this Tertiary orogeny is not seen on no fault interpretation using the same data.
    [Show full text]
  • Inheriting the Earth
    Earth Science, Astronomy and Space Astronomy Inheriting the Earth The Structure of the Earth The Crust as a Dynamic System Earthquakes, Volcanoes and Tsunamis Geological History The Universe The Journey of a Star The Solar System Space Technology Project by Asian Geographic Magazines Pte Ltd Publisher: John Thet Senior: Editor Lunita S V Mendoza Editor: Shreya Gopi Proofreader: Ian Seldrup Writers: J R Kayal, Yoav Bar-Ness, Astrid S Tiefholz and Moustafa Osman (Osman Consulting Ltd.) Designer: Zoey Lim Photos: Wikimedia Commons, USGS, NASA, NOAA Distributed by Young Prodigy Production (Thailand) co., Ltd 71/26 Soi Tan Phu Ying Phahol, Ladyao, Jatujak, Bangkok 10900 Tel: 02 – 9412349 ext 36 Fax: 02 – 941 2969 1 Chapter page CONTENTS 1 4 THE STRUCTURE OF THE EARTH • A Spherical Orb • The Spheres – Inside the Earth • The External Spheres • The Dimensions of the Sphere • The Heart of the Planet • The Furnace at the Core • The Mantle • The Crust: Ocean and Continent 2 10 THE CRUST AS A DYNAMIC SYSTEM • What Are Tectonic Plates? • The Dance of the Continents • Evidence for Continental Drift • The Supercontinents of the Distant Past • Plate Tectonic Boundaries: • Understanding the Map • Divergent Plates – Drivers of Motion • The Mid-Atlantic Ridge – Mover of Continents • Magnetic Stripes • Convergent Plates – Titanic Collisions • Smashing Lands – Continental Convergences • Destruction: Ocean Crust versus Continental Crust • Ocean Crustal Collisions – Arcs of Islands • Transform Boundaries – When Plates Slide Past • On Land and Under Sea 3 20
    [Show full text]
  • An Access-Dictionary of Internationalist High Tech Latinate English
    An Access-Dictionary of Internationalist High Tech Latinate English Excerpted from Word Power, Public Speaking Confidence, and Dictionary-Based Learning, Copyright © 2007 by Robert Oliphant, columnist, Education News Author of The Latin-Old English Glossary in British Museum MS 3376 (Mouton, 1966) and A Piano for Mrs. Cimino (Prentice Hall, 1980) INTRODUCTION Strictly speaking, this is simply a list of technical terms: 30,680 of them presented in an alphabetical sequence of 52 professional subject fields ranging from Aeronautics to Zoology. Practically considered, though, every item on the list can be quickly accessed in the Random House Webster’s Unabridged Dictionary (RHU), updated second edition of 2007, or in its CD – ROM WordGenius® version. So what’s here is actually an in-depth learning tool for mastering the basic vocabularies of what today can fairly be called American-Pronunciation Internationalist High Tech Latinate English. Dictionary authority. This list, by virtue of its dictionary link, has far more authority than a conventional professional-subject glossary, even the one offered online by the University of Maryland Medical Center. American dictionaries, after all, have always assigned their technical terms to professional experts in specific fields, identified those experts in print, and in effect held them responsible for the accuracy and comprehensiveness of each entry. Even more important, the entries themselves offer learners a complete sketch of each target word (headword). Memorization. For professionals, memorization is a basic career requirement. Any physician will tell you how much of it is called for in medical school and how hard it is, thanks to thousands of strange, exotic shapes like <myocardium> that have to be taken apart in the mind and reassembled like pieces of an unpronounceable jigsaw puzzle.
    [Show full text]
  • AP US History (APUSH) Summer Assignment
    Name ________________________________________________________ AP United States History Summer Assignment Director of Secondary Humanities Mrs. G. Sesso AP U.S. History Teachers Mr. S. Alfano Mrs. L. Klein Mrs. L. Matheson Instructions: Please have this entire assignment prepared and ready to be discussed on the first day of classes. Resources: • #1. American Pageant p. 4-11 (p. 7 intentionally omitted) • #2. A Cultivated World, 1491: New Revelations of the Americas Before Columbus, By Charles Mann. Reviewed by Alan Taylor. New York Times, Sunday August 7, 2005. • #3. Crosby, Alfred. The Columbian Exchange. History Now: The Journal of the Gilder Lehrman Institute. The Age of Exploration. www.gilderlehrman.org. • #4. Richter, Daniel. Native American Discoveries of Europe. Perceptions of Native Americans. The Gilder Lehrman Institute of American History. www.gilderlerman.org. • #5. Bartolome De Las Casas, "Brief Account of the Destruction of the Indies." • #6 Juan Gines De Sepulveda, "Concerning the Just Causes of the War Against the Indians." Read Resource #1 and answer the following 3 prompts in the space provided: Summarize the human migration and agricultural development of North America prior to the arrival of Europeans in 1492. Summarize the impact Native Americans had on the environment before the Europeans arrived in 1492. List the characteristics of pre-Columbian societies as presented by the text. Read Resource #2 and answer the following in the space provided: How does the book review of 1491 add to or differ from the textbook? Explain. Read Resource #3 and answer the following: Does Crosby's essay surprise you? Why or why not? What is Crosby's point of view on the Columbian Exchange? Cite at least one piece of evidence that confirms your answer.
    [Show full text]
  • Tasmanian Overland
    Tasmanian Overland J GR HARDING (Plates 41-44) As Earth's wild places contract, so have lands once reviled become our new adventure playgrounds. Such has been the experience ofTasmania, which first intruded upon the European conscious­ ness with Abel Tasman's discovery in 1642 - 128 years before Captain Cook's Australian landfall. Christened by Tasman Van Diemen's Land, its geography remained a mystery until Flinders' circumnavigation in 1799 which established it as an island rather than an appendage of the mainland. Four years later the first settlers arrived and starved. For the next 50 years of the 19th century, Van Diemen's Land became notorious as the principal penal settlement for Britain's transported convicts. In convict lore this was the Fatal Shore, the land of white slavery, and 'to plough Van Diemen's Land' argot for a convict's life of retribution. When transportation was finally abolished in 1853 and the name Tasmania substituted for Van Diemen's Land, the systemized brutality which had characterized the white man's life-style had been transmitted into a campaign of genocide against the Aborigines. Within 45 years of British settlement, the dreamtime had turned nightmare and primitive man had been exterminated from the land he had inhabited for millennia. For many years, little was written or read of Tasmania's 19th-century history; but as time shades and perceptions change, the convict stain has been expunged and to modern visitors the reputation of Victorian Tasmania would be incomprehensible. In the island continent of Australia, the flattest and driest on earth, whose predominant physical characteristic is inconspicuousness, this offshore isle with abundant rainfall, forests and mountains is almost unique in its display of genuinely dramatic scenery.
    [Show full text]
  • Continental Drift Notes (Chapter 7 Section 1)
    Continental Drift Notes (Chapter 7 Section 1) I. Important Terms: Pangaea: means All Land Continental Drift: All continents were once connected in a single large landmass. They broke apart about 200 million years ago and drifted apart to their current positions. II. Alfred Wegener – Developed Theory of Continental Drift • Alfred Wegener was a German meteorologist (studied weather) credited with development of the Continental drift theory. • Wegener observed the east coast of South America and the west coast of Africa fit together like puzzle pieces. • His ideas were NOT accepted by other scientists of his time. o The missing piece from his theory was sea floor spreading (the How?). Wegener did not have the technology to travel to the sea floor and collect samples of rock. o It was not until after his death that evidence was gathered to support his theory and his theory was finally accepted. III. Wegener’s Evidence to Support his Theory of Continental Drift • The puzzle-like fit of the South America and Africa • Fossils and Plants o Fossils of Mesosaurus (a fresh-water, land-dwelling reptile) were found in both Africa and South America. § How can it get across a great body of salt water? o Fossils of Glossopteris (a tropical, fern-like plant) were found in Antarctica, Australia, India, South America and Africa. § Strange? Tropical meaning warm temperatures and high humidity; Antarctica meaning cold temperatures and no sunlight for part of the year § Is this possible? o Other fossil evidence exists as well. (Fossil Safari) More Evidence that Supported Wegener’s Theory of Continental Drift… • Climate Clues o He found evidence of glaciers in tropical areas.
    [Show full text]
  • Speculations on the Mechanisms for the Formation and Breakup of Supercontinents
    Geoscience Frontiers 4 (2013) 185e194 Contents lists available at SciVerse ScienceDirect China University of Geosciences (Beijing) Geoscience Frontiers journal homepage: www.elsevier.com/locate/gsf Research paper Speculations on the mechanisms for the formation and breakup of supercontinents J. Brendan Murphy a,*, R. Damian Nance b a Department of Earth Sciences, St. Francis Xavier University, Antigonish, Nova Scotia B2G 2W5, Canada b Department of Geological Sciences, Ohio University, Athens, OH 45701, USA article info abstract Article history: The supercontinent cycle has had a profound effect on the Earth’s evolution since the Late Archean but Received 17 May 2012 our understanding of the forces responsible for its operation remains elusive. Supercontinents appear to Received in revised form form by two end-member processes: extroversion, in which the oceanic lithosphere surrounding the 9 July 2012 supercontinent (exterior ocean) is preferentially subducted (e.g. Pannotia), and introversion in which the Accepted 18 July 2012 oceanic lithosphere formed between dispersing fragments of the previous supercontinent (interior Available online 21 August 2012 ocean) is preferentially subducted (e.g. Pangea). Extroversion can be explained by “topedown” geo- dynamics, in which a supercontinent breaks up over a geoid high and amalgamates above a geoid low. Keywords: Supercontinent cycle Introversion, on the other hand, requires that the combined forces of slab-pull and ridge push (which Introversion operate in concert after supercontinent break-up) must be overcome in order to enable the previously Extroversion dispersing continents to turn inward. Introversion may begin when subduction zones are initiated along Pangea boundaries between the interior and exterior oceans and become trapped within the interior ocean.
    [Show full text]