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Marine Geology Exploring the New Frontiers of the Ocean Revised Edition Jon Erickson Foreword by Timothy Kusky, Ph.D. Copyright © 2003, 1996 by Jon Erickson All rights reserved. No part of this book may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage or retrieval systems, without permission in writing from the publisher. For information contact: Facts On File, Inc. 132 West 31st Street New York NY 10001 Library of Congress Cataloging-in-Publication Data Erickson, Jon, 1948– Marine geology: exploring the new frontiers of the ocean / Jon Erickson.—Rev. ed. p. cm.—(The living earth) Includes bibliographical references and index. ISBN 0-8160-4874-6 (hardcover: alk. paper) 1. Submarine geology. 2. Marine biology. I.Title. QE39 E68 2003 551.46’08—dc21 2002001295 Facts On File books are available at special discounts when purchased in bulk quantities for businesses, associations, institutions, or sales promotions. Please call our Special Sales Department in New York at 212 967-8800 or 800 322-8755. You can find Facts On File on the World Wide Web at http://www.factsonfile.com Text design by Cathy Rincon Cover design by Nora Wertz Illustrations by Jeremy Eagle, © Facts On File Printed in the United States of America VB Hermitage 10 9 8 7 6 5 4 3 2 1 This book is printed on acid-free paper. CONTENTS Tables v Acknowledgments ix Foreword xi Introduction xiii 1 THE BLUE PLANET: THE WORLD’S OCEANS Origin of Sea and Sky I The Universal Sea I The Iapetus Sea I The Panthalassa Sea I The Tethys Sea I The Atlantic 1 2 MARINE EXPLORATION: DISCOVERIES ON THE SEABED Exploring the Ocean Floor I Surveying the Seabed I Geologic Observations I Ocean Drilling I Magnetic Surveys I Satellite Mapping 31 3 THE DYNAMIC SEAFLOOR: THE OCEANIC CRUST Lithospheric Plates I Oceanic Crust I The Rock Cycle I Ocean Basins I Submarine Canyons I Microplates and Terranes 60 4 RIDGES AND TRENCHES: UNDERSEA MOUNTAINS AND CHASMS The Midocean Ridges I The Heat Engine I Seafloor Spreading I Basaltic Magma I The Circum-Pacific Belt I The Deep-Sea Trenches I Plate Subduction 87 5 SUBMARINE VOLCANOES: Eruptions ON THE OCEAN FLOOR The Ring of Fire I The Rising Magma I Island Arcs I Guyots and Seamounts I Rift Volcanoes I Hot-Spot Volcanoes I Volcanic Activity 114 6 ABYSSAL CURRENTS: OCEAN CIRCULATION Rivers in the Abyss I El Niño I Abyssal Storms I Tidal Currents I Ocean Waves I Seismic Sea Waves 145 7 COASTAL GEOLOGY: THE ACTIVE COASTLINE Sedimentation I Storm Surges I Coastal Erosion I Wave Impacts I Coastal Subsidence I Marine Transgression 172 8 SEA RICHES: RESOURCES OF THE OCEAN Law of the Sea I Oil and Gas I Mineral Deposits I Energy from the Sea I Harvesting the Sea 201 9 MARINE BIOLOGY: LIFE IN THE OCEAN Biologic Diversity I Marine Species I Life in the Abyss I Coral Reefs I The Vent Creatures I The Intertidal Zone 229 10 RARE SEAFLOOR FORMATIONS: UNUSUAL GEOLOGY ON THE SEABED Mud Volcanoes I Subsea Geysers I Submarine Slides I Sea Caves I Seafloor Craters I Undersea Explosions 257 Conclusion 285 Glossary 286 Bibliography 297 Index 305 Tables 1 The Geologic Time Scale 2 Radiation and Extinction of Species 10 Evolution of the Biosphere 12 The Major Ice Ages 13 Continental Drift 47 Comparison of Magnetic Reversals with Other Phenomena 56 Classification of the Earth’s Crust 66 The Amount of Carbon Relative to Life 72 History of the Deep Circulation of the Ocean 76 The World’s Ocean Trenches 107 Comparison of Types of Volcanism 115 Major Volcanic Disasters of the 20th Century 118 Classification of Volcanic Rocks 121 Major Tidal Bores 163 The Beaufort Wind Scale 179 Major Changes in Sea Level 194 Natural Resource Levels 202 Productivity of the Oceans 226 Classification of Species 235 Acknowledgments The author thanks the National Aeronautics and Space Administration (NASA), the National Oceanic and Atmospheric Administration (NOAA), the U.S. Army Corps of Engineers, the U.S. Department of Agriculture-Forest Service, the U.S. Department of Agriculture-Soil Conservation Service, the U.S. Defense Nuclear Agency, the U.S. Department of Energy, the U.S. Geological Survey (USGS), the U.S. Maritime Administration, the U.S. Navy, and the Woods Hole Oceanographic Institution (WHOI) for providing photographs for this book. The author thanks Frank K. Darmstadt, Senior Editor, and the rest of the Facts On File staff for their invaluable contributions to the making of this book. Foreword Oceans cover approximately two-thirds of the Earth’s surface yet we have explored less of the ocean’s depths and mysteries than the surfaces of several nearby planets. The oceans have inspired myths and legends and have been the sources of intrigue, fear, and hope for thousands of years. They have hindered migration of peoples and biota between distant continents yet paradoxically now serve as a principal means of transportation. Oceans provide us with incredible mineral wealth and renewable food and energy sources yet also breed devastating hurricanes. Life on Earth may have begun in environments around hot volcanic events on the seafloor, and we are only beginning today to explore the diverse and unique fauna that thrive in deep, dark waters around similar vents. In the revised edition of Marine Geology Jon Erickson explores several ideas hypothesizing the origin of the Earth continents and oceans and how these processes fit into the origin of the universe The role of oceans and water in the development of plate tectonics is discussed in detail while the reader is given essential information on how plate tectonics works Ocean basins have continually expanded and contracted on Earth and the continents have alternately converged into large single supercontinents and then broken apart by the formation of new ocean basins The appearance evolution and extinction of different life-forms are inextricably linked to the expansion and contraction of ocean basins partly through the changing environmental conditions associated with tectonic processes The history of several different ocean basins over the past billion years is discussed in Marine Geology as well as the changing life-forms in each successive ocean basin Ocean circulation is responsible for much of the world’s climate Mild foggy winters in London are caused by warm waters from the Gulf of Mexico flowing across the Atlantic in the Gulf Stream to the coast of the British Isles Large variations in ocean and atmospheric circulation patterns in the Pacific lead to alternating wet and dry climate conditions known as El Niño and La Niña These variations affect Pacific regions most strongly but are felt throughout the world Other movements of water are more dramatic including the sometimes devastating tsunami that may be initiated by earthquakes volcanic eruptions and giant submarine landslides One of the most tragic tsunamis in recent history was generated by the eruption of the Indonesian volcano Krakatau In 1883 When Krakatau erupted it blasted out a large part of the center of the volcano and seawater rushed in to fill the hole This seawater was immediately heated and it exploded outward in a steam eruption and a huge wave of hot water The tsunami generated by this eruption reached more than 120 feet in height and killed an estimated 36500 people in nearby coastal regions In 1998 a catastrophic 50-foot-high wave unexpectedly struck Papua New Guinea killing more than 2000 people and leaving more than 10000 homeless The oceans are full of rich mineral deposits including oil and gas on the continental shelves and slopes and metalliferous deposits formed near midocean ridge vents Much of the world’s wealth of manganese copper and gold lies on the seafloor The oceans also yield rich harvests of fish and care must be taken that we do not deplete this source by overfishing Sea vegetables are growing in popularity and their use may help alleviate the increasing demand for space in fertile farmland The oceans offer the world a solution to increasing energy and food demands in face of a growing world population New life-forms are constantly being discovered in the ocean’s depths and understanding these creatures is necessary before any changes we make to their environment causes them to perish forever — Timothy M. Kusky, Ph.D. Introduction This planet contains so much water that perhaps it should have been better named Oceania It is the only known body in the solar system that is surrounded by water filled with unique geologic structures and teeming with a staggering assortment of marine life Some of the strangest creatures on Earth whose ancestors go back several hundred million years live on the deep ocean floor Many undersea ridges host an eerie world that time forgot a cold dark abyss consisting of tall chimneys spewing hot mineral-rich water that supports unusual species previously unknown Ключевые слова: formed, heat, seafloor, beach, midatlantic ridge, material, deep-sea floor, massive quantity, carbon, spreading, science, ocean floor, polar meltdown, tidal basin, surface, nile delta, region, activity, rigid plate, long, seawater, great chunk, midocean ridge, great success, current pick, marine mammal, ha, pacific, foot, exotic chimney, hot spring, continental shelf, earth, great, courtesy, volcanic, total darkness, ice crystal, nazca plate, midocean, ocean, continent, gas, magnetic reversals, level, photo, marine ecology, enclosed basin, subduction, temperature, undersea, marine geology, geologic, constant rain, life, east-west wrinkle, highly explosive, coral, equatorial, tidal, magnetic stripe, artists rendition, ship, oceanic, crystalline cage, current, depth, wavelike progression, ice, hot-spot track, fish, mile, volcanic outgassing, continental glacier, mid-atlantic ridge, nio, national oceanic, water, kerr richard, global tectonics, largest, coast, ridge, hot, greek meaning, sea, vessel samuel, volcanic spasm, pressure, scientific, nova scotia, eruption, rip current, intrusion high, large, major decline, massive rockslide, organic material, kamchatka peninsula, submarine, rise, coastal, piston corer, volcano, rate, oceanic crust, kerguelen islands, floor, formation, manned submersible, drill bit, island, major, atlantic, large lake, hot spot, usgs, pack ice, strangest creature, living, gravitational attraction, tectonic activity, year, marine species, mantle, energy, geology, mesozoic era, flow, mineral, gorda ridge, drake passage, macquarie ridge, subduction zone, ophiolite complex, sea level, continually remake, lithospheric plate, extremely explosive, raw material, specie, sediment, land, california-sized chunk, lateral fault, oceanic plate, trench, marine, crust, mirror image, zone, hawaiian islands, tsunami, north, wa, wind, galpagos islands, wave, lava, form, mauna loa, planet, scientific american, cubic yard, predominately basaltic, deeply submerged, mariana islands, deep, magma, earthquake, submarine canyons, tallest mountain, time, nia, accretionary prism, black smoker, organic compound, submarine slide, american, volcanic activity, major influence, south, reef, layer, suez canal, basin, geologic column, great sloshing, intertidal zone, antarctica, aleutian islands, grand canyon, giant blob, high, basalt, spreading ridge, uss bennington, storm, america, economic zone, abyssal plain, continental, tide, tidal bore, south america, richard, plate, deposit, area, rock, oil, animal