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    Lakes

    Jeanne K. Hanson

    Foreword by Geoffrey H. Nash, Geologist

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    LAKES

    Copyright 2007 by Jeanne K. Hanson

    All rights reserved. No part o this book may be reproduced or utilized in any

    orm or by any means, electronic or mechanical, including photocopying,recording, or by any in ormation storage or retrieval systems, withoutpermission in writing rom the publisher. For in ormation contact:

    Chelsea House An imprint o In obase Publishing132 West 31st StreetNew York NY 10001

    ISBN-10: 0-8160-5914-4ISBN-13: 978-0-8160-5914-0

    Library of Congress Cataloging-in-Publication DataHanson, Jeanne K.

    Lakes / Jeanne K. Hanson; oreword, Geo rey H. Nash.p. cm. (The extreme earth)

    Includes bibliographical re erences (p. ) and index.ISBN 0-8160-5914-41. Lakes. I. Title: 10 o the most unusual lakes. II. Title. III. Series.GB1603.7.H36 2007551.482dc222005034327

    Chelsea House books are available at special discounts when purchased in bulkquantities or businesses, associations, institutions, or sales promotions.Please call our Special Sales Department in New York at (212) 967-8800or (800) 322-8755.

    You can fnd Chelsea House on the World Wide Web athttp://www.chelseahouse.com

    Text design by Erika K. ArroyoCover design by Dorothy M. Preston/Salvatore Luongo

    Illustrations by Melissa EricksenPhoto research by Diane K. French

    Printed in the United States o America

    FOF VB 10 9 8 7 6 5 4 3 2 1

    This book is printed on acid- ree paper.

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    Foreword by Geoffrey H. Nash viiiPreface x

    Acknowledgments xiiIntroduction xiii

    Origin of the Landform: Lakes 1 Why? 2Lake Formation 2

    A Lake: How Much Water? 3Ten Lakes 4

    1 G Caspian Sea, Middle East 5Geopolitics 5Low Elevation 7

    Origins: First Stages 8Origins: Middle Stages 9Desert Surroundings 9

    Saline Lakes in Dry Environments 10Rivers 10

    Life in the Caspian 11Salinity 12Salt Features 14Tectonic Features 14Oil and Natural Gas 15

    In the Field: Lake Levels and Core Sampling 16In the Field: Lake Levels and Their Dates 17In the Field: Climate, Salinity, and Other Water Chemistry 18

    In the Field: Economic Geology 18

    ContentsGGGGGGGGGG G GGGGGGGGGG

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    2 G Aral Sea, Western Asia 20Formation 20Present Form 22Drastic Changes Begin 22

    Anthrax Island 23Reasons for Shrinkage 23

    The Oceans of the World and Their Salt 25Effects of the Shrinkage 25Hard to Fix 25Salinity 26Dust 27Health Effects 27

    What Can Be Done 28In the Field: Satellite Imagery 28

    The Black Sea and the Origin of the Carp 29

    3 G Lake Superior, North America 30Depth and Tides 31

    Slate Islands 33 Watershed 33Origin 34

    After the Land Formed 34 A Failed Ocean 35The First Basin 37

    What Happened Next 37

    Ouimet Canyon 37The Glacier 38Position of the Glacier 38

    How Fast Does the Earth Move? 39The Glaciers Thickness 39Glacial Stages 39Lake Levels 40Ores 42

    Lake Superior v. Lake Malawi 42 Water Quality 43

    In the Field: Mercury Testing 44In the Field: Light Budgets 45The Lake in the World 46

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    4 G Lake Baikal, Central Asia 48Depth 48Cold and Wild Terrain 49The Galpagos of Russia 50Oldest But Still New 51

    An Even ColderBut InvisibleLake 51Rifting 52

    Rift Valley Lake, Asian Lake 53Shoving around the Edges 53Two Kinds of Rifting Here 54Rifts and Glaciers 54Glaciation Shapes Baikal 55

    Why Glaciers? 56Heat Forces 57Future Ocean? 57Heat Layering 58How This Works: Spring Turnover 58Summer Layers 59Fall Turnover Leads to Winter 59Pollution 60

    An Old Lake and Evolution 60 A Lake Studied Intensively 61In the Field: Drilling Cores 61In the Field: Carbon 14 Rock Dating 62In the Field: Potassium Rock Dating 63

    In the Field: Magnetic Polarity Dating 64In the Field: Neutrino Experiments 64

    5 G Lake Titicaca, Western South America 66Tectonic Origins 67Stages of Development 68Glacial Origin 69Lake Chemistry 70Climate Change and Local Agriculture 72Lake Levels Yield Much Information 72

    Tropical Lakes Can Explode 72 Ancient Local Agriculture and Nitrogen 73

    Lake Levels and Glaciation 73Lake Levels and Atmospheric Rainfall Patterns 74

    A Lake under a Desert 74

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    Lake Levels and Salinity 75In the Field: Reading Cores 75

    6 G Lake Vnern, Northern Europe 77Origins 79

    Glacial Origins 79 Why Glaciers? 80Position and Shape of the Continents 80

    Heyday of the Glaciers 81Ocean Currents and Glaciers 82Small Changes, Big Effects 83The Tilt of the Earth 83Milankovitch Cycles 84More Research Needed 84

    Will the Ice Age Continue? 84

    Lake Acidity 85Oxygen in the Lake 85 Pollution Challenges 86

    More Lake Chemistry 86Mercury 88Other Pollutants 88In the Field: Pollen Counting 88

    7 G Lake Eyre, Australia 90Its Location 90

    Soil and Wildlife 92Outback Location 92Stable Geology Now 93

    A Lot of Action Before 93Glaciation 94

    Ancient Lake Levels 95Ice Age Lake Levels 96

    The Opposite: A Very Young Wet Lake 97Recent Geology 97Climate Clue: Dust 97In the Field: Hydrology after a Flood 98

    8 G Crater Lake, Oregon, United States 99Rock Features 100The Eruption 100Most Ancient Origins 101The Ocean Floods In 101

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    The Recent Era 101Crater Lakes Birth 103Water Clarity 103Water Budget 105Water Chemistry 105

    Other Crater Lakes 106Lake Temperature 106In the Field: Lake Study by Submersible 107In the Field: Lake Depths by Sounding 107

    9 G Great Salt Lake, Utah, United States 108Once Larger 109Why a Basin? 110

    Salty Lakes, Dryland Features 111Why Salty? 112

    A Salt Lake Habitat 112Water Chemistry 112In the Field: Seismic Profling 113

    10 G Great Slave Lake, Canada 114Origins 114

    Glacial Features: Kettle Lakes, Pingo Lakes,Glacial Potholes 115

    Depth and Rebound 116The Next Glacier? 118

    Arctic Features 118In the Field: Ice Cores 119In the Field: Mass Spectrometry 119

    10 Conclusion: Lakes 120Glossary 122Books 127

    Web Sites 129Magazines and Journals 132Index 136

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    L akes are not static geologic eatures, rozen in time and changeless;they are dynamic and changing, because o local and global infuencesthat are both natural and human-made. Geology is not just a study o thepast. We are currently living in the geologic age called the Holocene, the

    most recent o the geologic ages that mark the 4.5 billion years since theEarth was ormed. Even the oldest lakes are young in comparison to theage o the Earth because the inexorable orces o plate tectonics pushingthe continents in continuous motion have altered the sur ace o the planetdramatically.

    Lakes, by Jeanne Hanson, presents 10 examples o unusual lakesormed by the power ul orces o tectonic activity, glaciers, volcanism, andother agents. Depending on where you live, you may be lucky enough to bewithin an easy drive o some o these lakes that you can visit. When you goto these or other lakes, you will be more aware o the complexity lying just

    below the waves. In a world whose sur ace is dominated by salty oceans,reshwater is rare and worth appreciating, studying, and protecting. Allthis can start with understanding how lakes develop, age, and even disap-pear. With some basic in ormation about these superlative lake examples,you can even apply your knowledge to a small pond in a nearby park.

    Readers will be amiliar with several o the lakes discussed in this book:

    Lake Superior, one o the Great Lakes in the United States Crater Lake, located inside a volcano crater the Great Salt Lake, saltier than the ocean

    Other lakes discussed in this volume may not be as well known:

    the Caspian Sea, salty like a sea but really a lake Lake Baikal, the worlds oldest lake, and biggest by volume Lake Eyre, a body o water that sometimes disappears, then

    reappears.

    Characteristics that relate these lakes to one another are their rela-tive recent ormation and their rarity as bodies o reshwater. Di erences

    ForewordGGGGGGGGGG G GGGGGGGGGG

    G viii G

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    between lakes arise rom their respective size, depth, local geology, biol-ogy, climate, and human impacts to which they are each subject. All lakesare a ected by these infuences and respond to them eventually. No lakestays the same or long i you are looking at it rom the perspective o thegeologic timescale.

    Two recurring eatures o this book are the In the Field sectionsthat detail eld methods used by geologists like me to study lakes andthe authors insights into areas o study where uture scientists may wishto research urther. May this type o ocus spark the readers awarenessand interest in the natural sciences and lead to urther contributions tothe eld. By taking a world tour within the pages o this book, you willalso gain an appreciation o geography because these lakes are scatteredall over the planet.

    Lakes can be used as a detailed but accessible re erence to under-stand lake processes and also as a readable entry point into the connect-edness o all o the natural sciences. A re erence list is also included orthose who wish to investigate the topic urther. You never know wherethe search will take you.

    Geo rey H. Nash, Geologist

    Foreword G ix

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    G x G

    F rom outer space, Earth resembles a ragile blue marble, as revealed inthe amous photograph taken by the Apollo 17 astronauts in Decem-ber 1972. Eugene Cernan, Ronald Evans, and Jack Schmitt were some28,000 miles (45,061 km) away when one o them snapped the amous

    picture that provided the rst clear image o the planet rom space.Zoom in closer and the view is quite di erent. Far beneath the vastseas that give the blue marble its rich hue are soaring mountains and deepridges. On land, more mountains and canyons come into view, ruggedterrain initiated by movement beneath the Earths crust and then sculpt-ed by wind and water. Arid deserts and hollow caves are here too, exist-ing in counterpoint to coursing rivers, sprawling lakes, and plummetingwater alls.

    The Extreme Earth is a set o eight books that presents the geologyo these land orms, with clear explanations o their origins, histories, and

    structures. Similarities exist, o course, among the many mountains o theworld, just as they exist among individual rivers, caves, deserts, canyons,water alls, lakes, ocean ridges, and trenches. Some quali y as the biggest,highest, deepest, longest, widest, oldest, or most unusual, and these arethe examples singled out in this set. Each book introduces 10 superlativeexamples, one by one, o the individual land orms, and reveals why theseland orms are never static, but always changing. Some o them are inter-nationally known, located in populated areas. Others are in more remotelocations and known primarily to people in the region. All o them areworthy o inclusion.

    To some people, the ever-shi ting contours o the Earth are just somuch scenery. Others sit and ponder ocean ridges and undersea trenches,imagining mysteries that they can neither interact with nor examine inperson. Some gaze at majestic canyons, rushing water alls, or placid lakes,appreciating the scenery rom behind a railing, on a path, or aboard aboat. Still others climb mountains, foat rivers, explore caves, and crossdeserts, interacting directly with nature in a personal way.

    PrefaceGGGGGGGGGG G GGGGGGGGGG

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    L akes is written as a science tour o the world or readers. It is timetravel, too, unreeling the earth history o each o the 10 lakes eaturedby explaining what was there be ore the lake, how it ormed, how it haschanged, and why. It can be interesting to know what is ound under-

    oot, by the side o the road, part o an outdoor vacation, or otherwiseencountered.

    The 10 lakes range rom a giant saltwater lake (the Caspian Sea) toa polluted and shrinking lake (the Aral Sea), rom the most extensivelake (Lake Superior) to the lake with the greatest volume o water (LakeBaikal), to the highest lake large enough to be navigable (Lake Titicaca).In yet more variety, the chapters go on to eature Europes largest lake(Lake Vnern), a lake that sometimes vanishes (Lake Eyre), a lake thatormed a ter a volcanic explosion (Crater Lake), a salty lake that can lookpink (Great Salt Lake), and a subarctic lake (Great Slave Lake). In these

    ways, and more, the lakes chosen are extreme.The lakes o this book are in the Middle East, the United States,Russia, South America, Europe, Australia, and Canada. Even more lakes,ound elsewhere, are eatured in some o the boxed sidebars ound inthe chapters, including two lakes in A rica that explode, a lake in Cali-ornia that has turned to dangerous dust, and much more. The book is aworld tour, at the level o the rocks.

    Like the other books in this set, The Extreme Earth, this volumebegins with the Origins o the Land orm, a short chapter that providesthe ramework, describing the main ways lakes orm on this planet. I youread it be ore beginning the book and again be ore launching into eachchapter, you will be able to place each lake in perspective, arranging theurniture o the mind well.

    The book also eatures a bit o science-in-action. Each chapter in-cludes at least one In the Field section, which tells how geologists areusing various techniques to study that lake today. Readers who are con-sidering geology as a pro ession might even go back a ter fnishing the

    IntroductionGGGGGGGGGG G GGGGGGGGGG

    G xiii G

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    book to read all o these sections againthey are always at the end o thechapterto get a beginning sense o the feld.

    One thing these books will not do: settle a bet. Does Lake Baikalhold exactly 14,000 cubic miles (58,355 km 3) o water, or is the numberound on some Web site or in some almanac the correct one? In research-ing this book it quickly became evident that almost every source o ereddi erent numbers or the lakes dimensions. This is not because o care-lessness or ignorance on the part o either the author or sources. Morerain or less rain one year, or even one month, changes a lakes volume abit. Even a lakes length and width change depending upon when and howthose dimensions were measured. The beginning and ending dates or the

    various broad geological periods also di er among sources. In assemblingthe statistics or each lake in the book, we consulted many sources andhere provide the best approximations possible.

    xiv G Introduction

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    G

    V iewed rom space, our planet is blue and green, but mostly blue.More than 71 percent o the sur ace o the Earth is water, about36 million cubic miles (150 km 3) o it. Almost all o thismore than 97percentlies in the oceans as salt water. The remaining 3 percent, thereshwater, is composed o all o the groundwater (water owing under-ground), the glaciers, the rivers, and the lakes o the world. This bookocuses on the lakes.

    Freshwater is rare, so rare across the planet that it could be consid-ered blue gold. Without it, li e on this planet would not exist. So it isuse ul to learn about lakes, beginning with a glimpse at the big picture,the origin o this beauti ul and important land orm.

    Though a lake may look as though it has existed orever, re ectingthe sky and clouds in all their tones and shapes, this is not the case. TheEarth is an unquiet planet, constantly being shaped in our main ways,naturally and slowly. The frst is through the broad movements o huge

    plates o rooted rock. These thick pieces o the planets crust move acrossthe sur ace, gradually shi ting the landmasses, and the lakes within them,as a giant 3-D puzzle.

    Climate change over the ages is the second major orce to shape theace o the planet and the lakes upon it. It causes glaciers to thicken andshove the land, then melt in immense volumes, rivers to rush ast enoughover eons to sweep away hills and block valleys, rost to crack the rocksthat make up the mountains until even the mountains tumble down. Per-

    haps amazingly, most o the major lakes o the world owe their existenceto glaciers and their a termath.

    The third natural engine o our planet is tectonic/igneous activity,as exemplifed by earthquakes and volcanoes. They crack, push, and pileup the land, or breathe out deep heat rom underground that melts rock.Lakes can orm in the shapes they create.

    The ourth great shape-shi ter, erosion, is actually the most signif-cant o these orces o natural change, or the planet as a wholeand the

    G 1 GOrigin of

    the Landform Lakes

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    G Lakes

    trickiest. Its work o ten covers up evidence o the other three. Erosioncan push up enough soil to make a river slide aside, raise hills that changewhere the snowmelt ows, and fll in valleys with sediments. All theseorces set the stage or the creation, change, and elimination o lakes.

    Why?The frst and best questions about the natural world are always the whysand the hows. Why did a particular lake orm where it did and how longago? Why has it flled with water? Why is it changing, and what did itonce look like? Why is one lake so much saltier than another? What isits water chemistry, its biological activity? How do heat, the shape o thelakes basin, light, the waters in ow and out ow a ect the lake? Howdoes a lake turn over in the spring and all? How do changes in its oxy-gen, nitrogen, and other chemical levels change a lake? How is humanactivity altering the lake? Questions like these lead into geology, the study

    o the Earth across time. Lakes are part o its ocus.

    Lake FOrmatiOnLakes begin to orm in 10 main ways, as described below, with some o these much more common in occurrence than others. The frst, tectonic

    forces, can indeed orm lakes, as slabs o rock are li ted up or made toslump, creating a new basin where water can collect. Secondly, volcanicorces create lakes, as lava erupts then collapses into a new basin or owsout to dam a river. Landslides, a third mechanism, can also orm bodieso water, when a ood or earthquake moves enough rocky soil to dam a

    river. (Since this material is not as dense as rock, the dam o ten washesaway in a ew weeks or months, ending the li e o this kind o lake rela-tively quickly.)

    Glaciers, a ourth method o lake ormation, has been, and is, verysignifcant on our planet, especially in the Pleistocene epoch which beganabout 2 million years ago. These ice monsters both pressed the land downand scooped it out on a giant scale, creating the basins that we now knowas the Great Lakes as well as many other lakes large and small. Glaciersacted just as power ully when they melted. Even the Great Salt Lakebegan long ago with glacial meltwater.

    Less common methods o lake ormationby solution, by river, bywind, by shoreline change, by organic activity, and by deliberate action can also be important. One type o lake, a solution lake, can orm whengroundwater or sur ace water dissolves rock, usually limestone, creating asmall basin. Rivers also can create lakes, by blocking a valley, or changingtheir own course to fll a lowlands, or example. Wind orms lake basins,too, by piling up sand and gravel in which water can collect. (These lakes,though, are usually short-lived.) Shoreline changes also create lakes, whenpart o a larger lake or ocean becomes cut o rom its main body o water.

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    Origin of the Landform G

    Organic activity can even make lakes, especially when a great many plantsdie and orm a dam behind which water collects; this is more in commonin the tropics than in the temperate zones o the planet, and these lakesare usually not long-lived. The last method, lake ormation by deliberateaction o humans (with, believe it or not, the occasional contribution byonly one other animal, the beaver) is increasingly common. This kind o activity can create reservoirs, or decorative artifcial lakes, or orest pools.People are such champion land movers that our e orts displace morethan 40 billion tons o soil and rock each year, in house construction, min-ing, and highway building alone; some o this serves to create lakes.

    O the natural methods o lake ormation, only three create the larg-er, more varied, longer-lived lakes that will be the subject o this book:the tectonic orces, the volcanic orces, and the glaciers. These threeearth orces are so power ul that it is estimated that the tectonic orcesalone shove up about 14 billion tons o rock each year across the planet,orming mountains and cracking land in hal across hundreds o miles tocreate both rifts and basins. Volcanoes worldwide raise about 30 billiontons o rock up rom the ocean oor to make land in new places each yearand explode on land to create caldera or lakes. And glaciers, the mostsignifcant orce in lake creation o all, push about 4.3 billion tons o landaround annually, even now. This e ect is unimaginably less than whatthey accomplished in their most recent heyday just a ew thousand yearsago, when many lakes were made. A planet without these three energetic,dynamic orces would not have seen the creation o very many lakes. TheEarth will reward all the curiosity one can summon to the understandingo these major engines o change.

    a Lake: hOW much Water?Once a lake orms, it develops a water economy, a balance o some kindin its in ow/out ow budget. This involves several key actors. First, thein ow. Lakes receive their water rom precipitation (rain and snowmelt),rom ground ow (via runo , rivers, and the like), and rom groundwaterseeping in. The pattern o in ow changes with both season and climate. Itis also a ected by the shape o the lakes basin, the nature o the runo ,the rivers, and groundwater, and by the lakes location on the planet. Theposition o the lake with regard to the ocean makes an especial di er-ence, too, since lakes nearer to an ocean receive less rain all; it rains moreover land than over ocean worldwide, and more water evaporates romthe ocean than rom the land.

    The out ow o water rom a lake occurs in several ways. Evapora-tion and transpiration (plants consuming water) are key. Important alsoare ow over the sur ace (a river may draw water away rom a lake) andseepage o water into the land groundwater (though lakes usually leakonly near the shoreline).

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    G

    GGGGGGGGGGGGGGGGGGGGGGGGGG G 1 G

    ca an s a Middle East

    t he Caspian Sea, the largest lake in the world, is about 144,000 squaremiles (375,000 km 2) in extent, more than hal the size o Texas. Northto south, it stretches about 745 miles (1,199 km). The Caspian is also themost saline (the saltiest) lake on the planet. Ranging rom 3 percent to 8percent saline, it is almost hal as salty as the ocean.

    While the Caspian is called a sea because o its size, it is actually alake, surrounded on all sides by these Middle Eastern countries: Kazakhstan,

    Azerbaijan, Georgia, Turkmenistan, and Iran. Once controlled by the SovietUnion, be ore that country broke up into republics in 1991, the Caspian lieseast o the Black Sea and even arther east o the Mediterranean. The BlackSea and the Mediterranean Sea, unlike the Caspian, are both connected tothe ocean.

    At shore level in most places, this is an immense, hot, dry, salty place. Itis ringed by low desert to the north, a higher desert plateau (called a grassysteppe) to the east, the Caucasus Mountains not ar to the west, and anarea o cropland to the south where sugarcane, ruit, and other oods aregrown. A huge desert lies just south o that zone. Desert is encroachingevery year on the Caspians southwest and south sides, a process called de-sertifcation. This land change generally results not only rom poor rain allbut also rom human practices that increase soil erosion or worsen soil qual-ity, damaging the conditions plants need to grow (the unanchored topsoilthen blows away). Sand dunes lie on parts o the Caspians east and southshores. Shaped and changed by wave action and wind action, the southern

    dunes rise as high as 50 eet (15.24 m) above the Caspian.

    GeOpOLiticsThe political position o the Caspian Sea is dramatic, too. Vast oil and natu-ral gas reservesgeologic in originlie around its shores and under its wa-ters. One o these, the Kashagan oil feld, sprawls north and northeast o the lake in Kazakhstan, and is the largest area o oil discovery worldwide in

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    G Lakes

    nearly 50 years. This feld should yield 13 billion barrels o oil, more eventhan Saudi Arabias immense oil felds, once it becomes urther developed.But or nearly 100 years already, oil has been pumped out o parts o theCaspian area.

    All fve o its border countries are vying or control o the Caspians sea-bed (underwater) oil, and that makes geological study and exploration espe-cially active here. Multinational oil companies are jockeying or position toexploit both this oil and the huge reserves o natural gasand then to moveit to the West through new pipelines they have been constructing. Westerncountries are among those involved, including the United States. This group

    has won the main pipeline route it wantedacross Georgia to Turkeythusavoiding the transit o most o the Middle Eastern countries.The Azerbaijani capital city o Baku, on the large Abseron peninsula

    jutting into the Caspian, is another rich area or lakebed oil, as well as animportant nexus or terrorists rom around the Middle East. Politics likethese are called geopolitics because they emerge rom the geography andgeology o an area.

    The Caspians geology is unusually interesting not only because it hasled to such salinity, but also because it is a place o tectonic activity that

    This schematic shows the size of the Caspian Sea in relation to selected other lakes and to the Black Sea, which isnot a lake since it is connected to the Mediterranean.

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    Caspian Sea G

    features major earthquakes, underwater volcanoes, and other seismic events(though no active volcanoes). The area is home, too, to the fossil fuels of oil and gas, whose exploitation is far more recent than the dramatic Earth-upheavals, which created the Caspian; these shall be discussed last.

    LOW eLeVatiOnThe Caspian Sea lies within a vast, low area of the planet. Its water con-ceals two especially deep basins, which together hold about 60 percentof the water volume of the lake. One is part of the southern part of thelake, and the other in its central stretch. The deepest point in the lake is

    This aerial view shows a winter scene at the Caspian, with mountains and a riverdelta. (CORBIS)

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    Caspian Sea G

    OriGins: middLe staGesDuring the early Miocene (close to 25 million years ago), mountain buildingbecame vigorous here. The land was squeezed, olded, and shoved south.The Alps were rising during the period 37 million to 23 million years ago,which overlaps with the early Miocene. This was the period in which the

    Caspians rich oil deposits ormed.By the time o the later Pliocene to Pleistocene (5 to 2 million yearsago), sediments were flling in the lowlands o Eurasia. By the time thesesediments reached about eight miles thick and solidifed into rock in theirlower layers, the olding began again, caused mostly by the Arabian plateshoving against the Eurasian plate. As the land olded, some o it rose tomake the areas mountains higher, and some o it ell lower. Quite low now,the Caspians basin began to deepen urther in the southern part o whatis now the lake.

    Moving the Earths crust here as though it were cooling ta y, the moun-

    tain building stretched the area in between the mountain ranges. That landis now under the northern part o the Caspian Sea. In a way mountainbuilding uses up more than its local share o the Earths crust, tugging it upand thus thinning the swatch o crust in between. The Earths crust underthe Caspian averages only fve to 9.3 miles (8 to 15 km) thick, compared toa world average o about 21.75 miles (35 km) or continental crust. Thin-ner sections o crust then subside, or slump, more readily.

    Because o all this mountain building, plate colliding, and land slump-ing in its origins, the Caspian Sea is classifed as a lake ormed by tec-tonic activity. To place that in perspective, please see Origin o the Land-orm: Lakes, earlier in the book, which describes the di erent wayslakes orm.

    desert surrOundinGsThe lowering o the land and the rising o the mountains set the stage orthe Caspian Seas next major eature, its desert surroundings and highlyrelated to that, its extreme salinity. (Its dryness can be seen in the colorinsert on page C-1.)

    High mountains change weather, and the mountains in the CaspianSeas part o the world began to do that immediately. They still do it today.Mountains cause the rain clouds that blow toward them to pile up on theside o the prevailing winds; the mountains and the warmer air they ex-hale are simply in the way o these clouds. The rain then alls on that sideo the mountains or on the mountains themselves. Almost none is le t toall on or near the land on the ar side o the mountains, here the Caspianbasin. This phenomenon, called the rainshadow o the mountains, is a ma-

    jor orce in creating the large deserts o the world, including the deserts o the Middle East. Even the Great Plains o the United States exists becausethat land lies in the rainshadow o the Rocky Mountains and so remains dry.

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    Rainshadows are broad shadows indeed. (Chapter 5: Lake Titicaca alsodiscusses them.) They have made the Caspian area a desert, which the heato the area has helped hugely to maintain. O course some water has allenor owed into the Caspian basin throughout history. Rivers do fnd theirway here. Gradually, water flled the basin to orm the lake.

    riVersThe rivers owing into the Caspian Sea rom the south and east includethe Kura, the Selfd-rud, the Atrek, and the Aras. They traverse a lot o desert and, throughout the long, hot summers, evaporation claims a greatdeal o their water.

    In North America, Europe, and areas o comparable latitude in the Southern Hemisphere, saline lakes arerather rare. Most o the lakes we know, rom the Great Lakes to the pond in the local park, are not saltwa-ter but reshwater. However, i one measures not the number o lakes but the volume o lake water, thetotal volume o water held by all the saline lakes on Earth would be almost as large as the volume held

    by all the reshwater ones. The Caspian Sea contributes a great deal to this equation.Saline lakes are unusual in many ways. Salty water reezes, on average, at F ( . C), not F

    (0C) as reshwater does. So a lakes strati cation (its layering based on heat exchange) is then di erent.Since salt water is heavier, it creates more water pressure, and that makes the lake colder at its deeperlevels than would be the case in reshwater. Salty lakes generally have a ewer number o species in-habiting them than reshwater lakes do, but these saline lakes usually have more individuals within thespecies they do have. In the salty lakes the Suns rays tend to penetrate more deeply; this is one o themany things about these lakes that is not well understood and will require attention rom the geologistso the uture.

    Overall, saline lakes have not been as extensively studied as reshwater ones, since reshwater is es-sential to human survival. The Caspian, however, has received a lot o research attention rom geologistsbecause o its oil and gas reserves.

    In a dry environment such as the one in this part o the world, the Caspian Sea waters evaporatereadily, precipitating out the salt, and though the Volga Rivers incoming water has been signi cantlyreduced by upstream dams, plenty o water remains in the Caspian Sea. Owens Lake, in Cali ornia, onceed by the Owens River rom the Sierra Nevada, has not been so lucky. Its water was diverted to bene tLos Angeles (whose land was once a desert) and Owens Lake has become a 0-square-mile ( -km )lakebed as dry as dust, all year long. The dry land is so salty that no plant on Earth can grow there.

    This salty soil is li ted by the winds, and the blowing dust is a major problem. The dust here is madeo silt and sand laced with arsenic. It has become our countrys largest single source o dust, airborne,inhaled by people, and dangerous to them. It creates air pollution alerts.

    Engineers are channeling part o the Owens River back toward its lake by pipeline, even thoughthis reduces the fow o water to Los Angeles. Owens Lake will appear again, shallowbut at least swal-lowing its own nasty dust. For a lake whose dust will remain toxic or a much longer time, please see thenext chapter, on the Aral Sea.

    SALINE LAKES IN D RY ENVIRONMENTS

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    The rivers rom the north and west, including Samur, the Sulak, theTerek, the Ural, and the Volga, are wider to begin with and contributemuch more water. They also drain much larger watersheds or drainage ar-eas, and their watersheds include mountains, which contribute snowmelt.More northerly, these rivers do not always traverse hot desert. Withoutthe northern rivers, along with some seabed springs, the Caspian wouldhave dried up long ago. Rivers as a whole bring in 80 percent o the Cas-pians water, groundwater springs, and seepage between 2 and 9 percent,and precipitation contributes only the small remaining portion.

    The Volga River, 2,291 miles (3,687 km) long, is by ar the majorinfuence on the Caspians water budget. It brings in more than three-ourths o the river water volume reaching the lake. The Volga creates adelta 124 miles (200 km) broad as it enters rom the north. Though the

    Across the planet the largest number o species o living things live in true saltwaterthe oceans. Sec-ond in popularity to this ull saltwater habitat is the reshwater one. The ewest number o species oc-cupy the in-between, brackish water o places like the Caspian Sea. Within this the very lowest numberlive in salinities o to percent. The Caspians salinity averages rom about percent to about per-cent, depending upon the area one is testing. So it has relatively ew species. (To put this in perspective,note that the very reshest reshwater contains pounds o salt per cubic oot ( ,0 kg/m ) o water,and the saltiest level in the oceans is . pounds per cubic oot ( ,0 kg/m ).

    Most species that manage to live in saline lakes evolved rst to live in reshwater and then adaptedto places like the Caspian. Two o the adaptations are a relatively impermeable body sur ace (to keepsalt rom being absorbed and resher fuids rom being eliminated) and an ability to get rid o salt easily.

    Some birds look a little as though they are crying because they can get rid o salt through their eye ducts.Other creatures produce very salty urine. Excess salt remaining in the body is atal to most creatures.The Caspian is home to untold numbers o bacteria and algae (common across the planet), with

    each species here adapted to a narrow range o the broad spectrum o salinities within the lake. Alsoinhabiting it are crabs, cray sh, bivalves (animals with two parts o their shells hinged, such as a clamor oyster), mollusks, some sponges, and other invertebrates. These are available to be eaten by the largercreatures.

    The very largest inhabitants are the sturgeon o the Caspian, giant sh who look primitive and areindeed ancient species. At about 00 million years old, the sturgeon is one o the oldest species on earth.Three o these ancient species are shed here extensively, the beluga sturgeon most o all. Its eggs areprized as an exceptional caviar, and the demand or them is very high.

    Un ortunately, the beluga has been signi cantly over shed. Azerbaijan captures about 0 percento the sturgeon in the world, right here in the Caspian Sea. The sh is also su ering rom the pollution,which will surely not diminish as oil and gas resources are urther exploited. The belugas are alreadycontaminated with DDT, PCBs, and other organochlorine compounds. Their numbers have dropped dra-matically.

    Even i progress is being made to preserve the belugas numbers, which is not clear, results wouldnot be signi cant or a long time. It takes this sh many decades to reach the size that used to be com-mon in the Caspian, its prehistoric army o sh.

    LIFE IN THE CASPIAN

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    desert areas, including the Great Salt Lake in Utah, subject o chapter 9. Water evaporates more in hot, dry climates, which leaves the natural saltbehind. Changes in lake level can then leave these salt deposits exposedon shore.

    The salts do not come rom the desert sand or the ocean directly.They build up as salty air blows in rom the ocean, as rocks, soils, andwind-borne dust release their natural salts, as soils erode, as rivers fow in,and as the evaporating water leaves behind its minerals. The rocks hereat the Caspian also hold ancient salt deposits, dating back to when thisarea was part o the Tethys Sea, one o our planets early oceans. Northo the Caspian lies a huge area o salty deposits and rock like this. In actit is part o one o the six-largest ancient evaporitic basins on the planet

    Salt domes like this lie just underground near the Caspian Sea, and the darkest areasshow where oil is typically found.

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    (low, evaporated areas). The saltiness o the Caspian is also greatly en-hanced as humans add both air and water pollutants, which contain salts.

    And here there is less water to dilute all these additions, since theCaspian is in a dusty, desert environment, as can be seen in the color in-sert on page C-1. Salinity levels average high here, nearly 13 parts salt perthousand o water, with up to 200 parts per thousand as the maximum incertain areas o the Caspian Sea.

    The salt o the Caspian is complex. It contains the common sodiumo table salt, and also calcium, magnesium, potassium, bicarbonate, car-bonate, sul ate, and chloride. Bromine, strontium, phosphate, and boron(not salts) also can be present. The balance among these chemicals isdi erent in various areas o the lake, and microbes in the lake use andchange its composition too.

    saLt Features

    With all its salt, the Caspian has created some unusual geological salteaturesand on a very large scale. One, called the Kara-Bogaz-Gol, is anatural evaporation area o the east shoreline. It is even lower in eleva-tion than the Caspian Sea itsel , about nine eet (2.7 m) lower. Here,throughout the year, the lake foods throughout the spring, then recedesthrough evaporation in the summer, leaving bare salt deposits. These arequite extensive. In one place the salt lies seven eet (2.1 m) thick, andcovers an area o more than 1,000 square miles (2,590 km 2).

    Salt also is concealed onshore, underground, in the Caspian area.These eatures, called salt domes, are common all around the lake. Formedas heavy rock layers above, the salty layer presses down and orces theso ter, more plastic salt to fow up and around harder rock (they resemblearmies o hidden hills). This shape is why they are called domes. Theunderground domes can be up to 500 eet (152 m) high. Their tops are

    just below the sur ace o the ground, since desert soils are continuallyblowing in to cover them. Over time salt can fow to the sur ace where ittypically washes away.

    Because this kind o compression and fow is also what leads to thepooling o oil deposits, the salt domes can be used as a marker or placesto drill. Salt domes are ound along the Gul Coast o the United States,too, where they are also associated with oil.

    tectOnic FeaturesOther geologic eatures o the Caspian Sea include earthquakes, sub-merged volcanoes, mud volcanoes, and other signs o the tectonic orcesacting here today. This is a restless area.

    Earthquakes are a danger especially on the south and east sides o the Caspian Sea. A deadly one hit Bam, Iran, in late 2003, killing thou-sands. A bit arther south, Irans capital, Tehran, could experience a

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    major quake at any time. Periodically, Iranians discuss moving theircapital, and all its 12 million residents, arther rom this zone, but theyhave not done so.

    Volcanic eruptions (volcanism) seem to have been going on in theCaspian Sea area or about 1.5 million years, with major periods o activ-ity, in di erent parts o the Caspian area, at 1.2, 1.1, and 0.8 million yearsago. What spews out o a volcano when it erupts is magma or hot ow-ing lava rock. Here, the magma orms as the crust under the CaucasusMountains is heated until the rock ows. The crust crumples and collidesunderground because o the convergence o the Arabian and the Eurasianplates. Their smashing provides the energy.

    Also here are mud volcanoes. Associated with geological faults inareas rich in oil and natural gas resources, these are not truly volcanoes.

    Almost never hugely explosive, they are bubbling blobs o mud, clay,salty water, and methane gas pushing up through mud and shale rockso the sea oor. They usually bring a bit o oil up with themand some-times a fsh!

    The tectonic activity that created the Caspian Seas basin is still shap-ing the land here today. It will not end in the oreseeable uture.

    OiL and naturaL GasThe geology o the Caspian makes it an area extremely rich in oil andnatural gas resources. Coal and uranium are also mined here.

    The Miocene (25 to 5 million years ago) was the most prolifc period,worldwide, or the ormation o these valuable ossil uels. During the

    Miocene in the Caspian area, mountains were rising and sediments wereflling in the low elevations alongside and between them. Sediments herereached eight miles (12.9 km) thick, signifcantly thicker than the typicalew kilometers (or a couple o miles) o sediment ound as the top layero continental crust around the world.

    These thick sediments, compressed by the immense weight o rocklayers above them, and heated by the orce o this pressure over mil-lions o years, are what make oil. The gasoline we pump into our carsis called a ossil uel because it is literally made o ossilsthe deadplants, animals, and soils that compose the sedimentspressed so hardor so long that they have turned into a thick liquid slurry lying withinsmall spaces in the rock. The process is a little like smashing a ripepeach with the heel o your handit will yield some peach juice alongwith the pulp.

    The most lucrative area or oil and natural gas here is called theCaspian Depression. This huge, low desert wraps around the northand some o the east side o the present lake. There are many otherareas o the Caspian that are also rich in oil. (Economic geologists studythese resources.)

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    in the FieLd: Lake LeVeLs and cOre sampLinGGeologists are actively studying the Caspian Sea. Their major areas o interest include: the lakes water levels, its climate, salinity and otherwater chemistry, and its economic geology and environmental change.One o their research techniques will be described or each o these areaso study.

    The water levels o the Caspian throughout its history reveal verylarge changes and seem to show cycles, the reasons or which are notyet well understood. Geopolitically, this area was long part o the SovietUnion, when most outside scientists were not allowed in to study it. Thatchanged a ter the Union split apart in 1991. Geologists typically fgureout earlier shorelines by analyzing the sediments near its present shoreand underwater; ossils o fsh indicate that the area was once underwa-ter, or example.

    The Caspian was probably at its most extensive about 1.2 millionyears ago, swollen with snowmelt rom the glaciers o Europe. (The wa-ter entered via the Volga River.) And, in act, it has had several very wideswings during fve di erent phases o glaciation in the Pleistocene (2 mil-lion years ago to today), the period o glaciers on the planet. Glaciersnever pushed as ar south as the Middle East, but their meltwater madeall the rivers wide and ull.

    To establish sea levels by examining sediments, geologists dig them up very care ully so as not to destroy or muddy the evidence. This is typicallydone by core sampling. (This technique is very important in geology and is

    also discussed in chapter 4: Lake Baikal, chapter 5: Lake Titicaca, chapter6: Lake Vnern, and chapter 10: Great Slave Lake.) Using a long hollowmetal tube and mechanical power (a kind o mining machine), the geolo-gist team orces the tube down through the loose beach sand or underwa-ter muck and arther down through a ew eet up to a ew hundred yardsor more o solid rock. Many o those rock layers were once sediments,now compressed into layers o soil, solid rock, and the detritus o livingthings. The core is then pulled straight back up within its metal casing.

    The next step is o ten to reeze-dry the core, hardening it to keep ittogether as the outer metal casing is removed. The core sample o rock isthen cut into thin slices at points, which appear relevant to the geologists.These ancient layers are analyzed in various high-tech ways, using, or ex-ample, X-rays, gas chromatography, mass spectrometry, and other tech-niques. This is done back in the geology lab with the help o technicians.

    Results are then compared by the geologist to the historical recordameasuring stick, in a senseestablished by previous geological work. Di-rect measurements o the lake levels here go back about 100 years, only astart. There are other, very long-term benchmarks. One o these involveslooking at the magnetic orientation o the magnetic rocks in the various

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    core slices. (Not every rock is magnetic, o course, but a core samplewill usually include some o these iron-rich rocks.) The Earth itsel is amagnet because o its iron-rich core and this whole planet magnet haschanged its polarity, or north-south orientation, periodically throughouthistory. It has ipped, as though the whole Earth were a bar magnet thatchanged its ends rom north to south and south to north. Every rockon the planet ollows the lead o the Earths core at the time that rocksolidifes, and some rocks have enough magnetism that their north-southorientation can be measured. This technique can help establish the age o a core sample slice since the ips o the planet have been dated; manyhave occurred even over the past 70 million years, creating a use ul yard-stick. (For more on magnetic polarity shi ts, please see chapter 4: LakeBaikal and chapter 5: Lake Titicaca.)

    In addition to the magnetism, the basic mineral nature o the rock inthe core samples is also investigated. It reveals much, such as when thelake was saltiest. This is visible as a layer where carbon-rich rock is morecommon than averagethis chemical is precipitated out o water duringevaporation, and evaporation is associated with higher salinity. Was a la-goon present here in certain periods, or was this area never underwater?Core sampling helps to fgure this out also.

    in the FieLd: Lake LeVeLs and their datesUsing core sampling and other research methods, geologists have put to-gether other in ormation on the Caspians water levels and looked or cy-cles or patterns in its changes. They have ound that during the Holocene( rom 10,000 years ago to today), also considered part o the Pleistocene,the lake has gone up and down 60 eet (18 m). Between 1929 and 1995,lake levels oscillated 20 eet (6 m) alone, which included a dramatic low-ering during the 1930s. The Caspian is currently considered high. Cycleso both 62.5 and 38.46 years in its rises and alls have been suggested butnot completely accepted. And some geologists have predicted that thelake will increase in size during this century. Much remains to be learnedhere, and this geological research certainly has implications or where theareas people should live, where they should explore or oil, and othersuch decisions.

    The causes or the changes in Caspian water level remain to be fguredout also. Some geologists think Northern Hemisphere climate change iskey. Others point to changes on the Sun (in its sunspot, or major storm,activity) as a ecting world climate in complicated ways not well under-stood. Others ocus on tectonic changes, earth movements that changethe shape o the lakes basin. And there are additional theories, too.

    As more is learned about the Caspians changes in water level, thatwill, in turn, enhance our understanding even o the glaciers and glacialmelt in the Soviet Arctic in Pleistocene times (about 2 million years ago

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    to current times), since the glacial meltwater caused lake levels to rise. Inact, paleogeology, the use o present studies to tell us about the distantpast, is an interest o many geologists. This kind o research is quite pro-ductive at the Caspian Sea.

    in the FieLd: cLimate, saLinity, and Other Water chemistry Among the techniques used by paleogeologists is the analysis o pollenspores. Power ul special microscopes can identi y and analyze the tinytree and plant pollen spores ound in the core samples. Cooler weath-er and warmer weather are better or di erent groups o plants, whichthen release more pollen during their heydays. One pollen study, whichlooked at 116 di erent species o pollen spores, suggested that summerswere signifcantly cooler at the Caspian Sea about 6,000 years ago thanthey are today. Geologists can rely on comparing the ancient pollen to

    known pollens rom various plants today since a plants pollen does notchange much.

    Climate changes throughout history at the Caspian Sea can also beglimpsed at by looking at the ossils o the sea creatures and plant detritusound in the core samples. Warmer or cooler periods can cause speciesto be eliminated entirelytheir ossils may be present in one layer andabsent in another, suggesting a change in climate.

    The salinity o the Caspian, probably its most salient eature, hasreceived a great deal o research attention also. Since the lake includes a

    variety o salts, and since the rivers bring in resher water, salinity varies

    throughout the lake. In one area alone it ranges rom 3.2 percent to 7.4percent. The salinity can help to concentrate metal pollutants in placeswhere a major river ows in. And it is also being studied to investigatethe economics o desalination, or turning salty water into reshwater, orhuman or at least industrial purposes. This is now very expensive, givenour present technology.

    Many other aspects o the lakes water chemistry are under study. Among them are its levels o trace uranium and the change in position o the Volga Rivers delta. Large-scale movements o water within the lake,which would mix its chemistry signifcantly, are apparently rare. The twodeepest areas exchange only 7 percent o their water per year. Anothersubject studied, with implications or drilling, is mud circulation. Tech-niques used here include aerial photography and remote sensing to maplarge-scale vegetation eatures.

    in the FieLd: ecOnOmic GeOLOGy Economic geology is a very important area o research in the Caspian area,though ewer o its results are ound in the regular scientifc journals than

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    other areas of research. Many economic geologists work for big oil andgas drilling and processing companies, which want to keep the researchprivate in order to use it in their business. Corporate investments in theCaspian have also only been possible since the Soviet Union broke up in1991, but they are fast and extensive now. The exploitation of salt re-sources here, active for well over 100 years, has become large-scale sincethe 1970s; though part of economic geology, it has not been a subject of so much secrecy.

    Among the things discovered in the Caspian area is that there are atleast six major underwater areas rich in oil and gas (in addition to the ar-eas on land); the latest new area of 100 promising sections was discovered

    just in late 2004. There may also be large pockets of natural gas trappedin thick layers of rock below the Caspian Sea. Other researchers havelooked at what might be the cheapest, but not necessarily the shortest,route for pipelines to move the areas immense oil and gas resources tomarkets around the world.

    Economic geology techniques include directing seismic waves downthrough the water or ground. Geologists can monitor how these wavesmay be slowed, or sped up, or bent, depending upon whether they arepassing through oil or nonoil sands or sediments. (For more on seismictechniques, please see chapter 8: Crater Lake.)

    Geological research in the Caspian also relates to environmentalchanges connected to oil exploitation. The Caspian has become a quitepolluted place. Oil and oil by-products leak into the lake, introducingcontaminants such as PAHs (polycyclic aromatic hydrocarbons). Meth-ane also pollutes the lake, as a result of natural gas and coal exploitation.The fossil fuel industries also emit carbon, sulfur, and nitrogen oxides.Radiation levels here are boosted by oil and uranium mining. In addition,mercury and metal concentrations in the lake are too high, probably alsothe result of mining operations. There is tremendous opportunity for ge-ologists to help with problems like these, here and elsewhere.

    The Caspian Sea is an immense lake. The saltiest lake in the world,partially surrounded by desert, its elevation is low and climate hot. Thearea is rich in resources from salt to oil and gas, though these industries aswell as others are contributing to its pollution.

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    i the Caspian Sea (the subject o chapter 1) sounds like an oddly un-attractive and environmentally degraded place, the Aral Sea couldannounce itsel as actually horri ying. Movie producers without con-cern or personal health could shoot a horror ick here. Readers maychoose to place this lake on a long list o sites to visit around the world in last place.

    A ter the preliminaries the degradation o the Aral Sea will be de-scribed. But do note: the rest o the lakes in this book are all wonder ulto encounter.

    The Aral Sea, bordered by Kazakhstan and Uzbekistan, lies north o the Caspian Sea in central Asia and east o the Ural Mountains (consid-ered the dividing line between Europe and Asia). Unlike the Caspian, ithas neither signifcant oil and gas resources, nor big cities nearby. Like the

    Caspian, it is called a sea because o its size, though it is, too, a lake,unconnected to any ocean.

    The Aral lies in an arid region o grassland steppes and desert plateaus,its environs a lot more like the Middle East than Europe. To its north andnorthwest the Arals area is mountains and grasslands. A low salty arealies to its east and southeast, and a much larger lower one stretches arto its north. A true desert called the Peski Bolshiye Barsuki extends eastand west o the Aral. The lake was once ed by two vigorous rivers, theSyr Darya and the Amu Darya, though they are now much diminished inow. It has three islands, Lazerew Oroli, Ostrov Barsakelmes, and Voz-

    rozhdeniye; the latter, to which we shall return later, is commonly calledRenaissance Island or Rebirth Island but is a dangerous place.

    FOrmatiOnThe ormation o the Aral Sea occurred because o tectonic forces, thelarge-scale movements o vast rocky plates that alter the position o theEarths landmasses over millions, even billions, o years. (These orces

    G 2 G GGGGGGGGGGGGGGGGGGGGGGGG

    a l seWestern Asia

    G 0

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    are commonly called plate tectonics. ) Very early in the Paleozoic epoch(500 to 235 million years ago), the continents were joined closely to-gether; but in what would become this part o the world, the land beganto split and old. A north-south strip gradually rose to become the UralMountains, this upli t zone extending rom just north o the Aral andCaspian Seas all the way to the Arctic. To the east and south o this up-li ted land lay part o an ancient ocean called the Tethys Sea. Part o thissalty sea lay over the land that is now the Aral.

    By the end o the Paleozoic, in a time period within it called the Permian (270 to 235 million years ago), the Arals general area becamepart o a huge evaporitic basin. The combination o salt deposits romthe nearby Tethys Sea, the relatively low elevation, and the high tem-peratures created a place where water evaporated to leave this low areao salty soil. Two vast areas north o the Aral and Caspian are known asone o the three largest such evaporitic basins on the planet.

    During the next epoch, the Mesozoic (235 to 70 million years ago),

    the continents fnished this period o splitting and landmasses reachedclose to their present positions. The basin that would become the AralSea became hot and desertlike, even though the Ural Mountains beyondand two rivers (now called the Syr and the Amu) ow toward it.

    Last, during the Cenozoic epoch (70 million years ago to the present),the old Tethys Sea area became completely reconfgured as more moun-tains were built. The tectonic plates that carry what is now A rica and

    This schematic of the continents locations 0 million years ago shows that the Aral Sea was once nearer to theoceans edge.

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    India collided with the Eurasian plate. The masses o rock that upli ted,then piled up, became the Alps, the Himalayas, and other ranges such asthe Caucasus. The Urals were also reshaped. The Indian Ocean and theMediterranean took their present positions ar rom the Aral Sea area,and the Tethys Sea vanished.

    present FOrmBetween these mountain ranges lower areas began to fll with runo wa-ter rom the mountains. One o these lower areas is now the Aral Sea. Ithas been here or about 2 million years.

    This part o the world has remained tectonically active, though thelands south o the Caspian Sea are much more so than the Aral Seas en-

    virons. In our present era the Aral has been shaped more by human actionthan by tectonic orces.

    The Aral Sea was once the largest reshwater lake in the world. As

    recently as 1960, it was rich in fsh and resh enough to drink. Then thisscenario changed. The lake became one o the worlds worst environmen-tal disasters, one that is still un olding today.

    drastic chanGes BeGinSince 1960 the Aral Sea has shrunk 70 percent in water volume and splitin two. By the 1990s it had shriveled to hal its original extent. The lakeslevel ell by 52.5 eet (16 m), and its waters became three times as salty.Its shoreline receded 30 miles (48.25 km) in some places and up to 60miles (96.5 km) in others, stranding ormer fshing villages in a new des-

    ert o toxic sand. Up to 85 percent o its cropland can now no longer bearmed. The Arals rivers today bring in a dribble o pollution where oncethey supplied ample clean water.

    The land in between the northern and southern parts o the Aral (oncean underwater ridge) is also contaminated with salt and agricultural chem-icals. One o the lakes islands, Rebirth Island, eatures an anthrax actoryrom the mid-20th century. This chemical, used as a weapon so toxic thatless than a teaspoon can kill a city, still contaminates the soil there.

    The slow, steady death o the Aral Sea continues today, damagingthe health o the population around it, an area most broadly defned as35 million people. Its degradation a ects not only Kazakhstan and Uz-bekistan but also Kyrgyzstan, Tajikistan, and Turkmenistan, all in itsdrainage basin.

    There is, however, one bright spot. Because o a new dam and waterdiversions, the small, northern section o the ormer Aral (about one-seventh o the whole lakes now shrunken size) that has been long cut o rom the large main southern section, is actually deepening. Levels havegone rom ewer than 98 eet (30 m) to 125 eet (38 m). Though lakelevels need to be 138 eet (42 m) to make fshing sustainable, some o the

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    fshermen, are returning. The main section o the Aral, however, is stilllikely to disappear.

    reasOns FOr shrinkaGeIn this part o the world precipitation is low, summer temperatures regu-larly climb to 120F (48.8C), and lake water evaporation is quick andcommon. So a lake needs to be ed by ample river water rom more dis-tant places, where rain all is more abundant, and mountain rivers need toprovide snowmelt. Two things have happened here to disrupt this system:Natural rain all has been reduced, and the river system has gone com-

    pletely awry. New islands also appear, as can be seen in the color inserton page C-1.In the days o the Soviet Union (191791), a vast country that in-

    cluded all o the countries around the Aral Sea, the power ul centralgovernment decided to divert the Arals two rivers. Their goal, which waslargely met, was to use the river water as irrigation, allowing this area togrow vast tracts o cotton even though it is a desert or near-desert zone.

    An agricultural operation like this typically uses even more water per acrethan a comparably sized city. The rivers were channeled away rom their

    This Aral Sea island, whose name Vozrozhdeniye is translated as Renaissance Island or Rebirth Island,is the ultimate unwise destination or a tourist visiteven within the heavily polluted environs o thislake. Biological weapons were made here, and the mess has still not been completely cleaned up.

    During the cold war o the 0s through the 0s, when the United States and other Western

    countries vied with the Soviet Union and other communist countries or power and control o the loyal-ties o the rest o the world, this island was part o that stri e. It became home to research on anthrax,a deadly microbe that can be used to make weapons o mass destruction. The laboratory on the islandalso investigated the organisms that create other deadly conditions. None o these dangerous organismsis visible to the naked eye, making the island hard to clean even i there were enough money and com-mitment to do so.

    A ter the Soviet Union disbanded in , the acility here in the Aral Sea was shut down, and mosto the killer germs were indeed deliberately exterminated. Anthrax, however, is particularly hard todispose o it lives easily in soil, spreading there to contaminate large stretches o land.

    This island was never properly guarded, and now, with the shrinkage o the Aral Sea, people canactually walk out to it, as can be glimpsed in the color insert. Looters are a problem, and now so aresmall burrowing animalssoil that is contaminated could easily be walked right back to the mainlandon their shoes and eet.

    Not until 00 was a clean-up agreement signed. The United States is paying Uzbekistan to decon-taminate Anthrax Island. Un ortunately, this has not yet been entirely accomplished.

    A ter the events o September , 00 , a new visit was made here by United States o fcials. Thegoal was to see i any contaminants might be available to terrorists. Journalists who have inquired andvisited since have not seen any real change, however.

    ANTHRAX ISLAND

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    courses and sent right through the cotton felds. Not only is cotton anespecially thirsty cropit needs water by gulps in order to growbutalso the irrigation ditches built to direct the water were not lined. A greatdeal o the water simply soaked into the ground without even reachingthe cotton plants.

    Agricultural chemicals, such as pesticides and ertilizers or increas-ing the cotton crop yields, were also added, and in excessive amounts.Large volumes o these pollutants, along with eroding salty soil, reachedthe Aral Sea in the vastly diminished volume o reshwater carried by therivers. The two main rivers, the Syr and the Amu, once brought morethan 24 cubic miles (100 km 3) o water per year into the Aral. Now bothrivers are narrower than 10 eet (3 m) wide. This recipe or a lake disas-ter, played out over decades, caused the Aral Sea to begin vanishing.

    In this aerial image one can see the shrinkage of the Aral as of its stage in .(NASA/CORBIS)

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    eFFects OF the shrinkaGeThe e ect o the lakes changes on the fsh alone has been dramatic. O the Aral Seas major fsh species, 20 out o 25 have died out completely.

    And, out o 178 species o animal in the area, only 38 species survive.The 5 million people who live close enough to need the Aral or their

    livelihood and or drinking water do not have many ways to make a livingin a part o the world so inhospitable to agriculture. They used to fsh,but the fshing villages now fnd very ew fsh to catch, and what fsh theydo fnd are much arther away. To reach them, the people have to traveldozens o miles across polluted sand dunes instead o walking down thestreet as they once did.

    It is estimated that 60,000 people have become unemployed as aresult o this Aral Sea disaster. Some o them have moved upstreamon the rivers and are proceeding to stress the water supply even morerom there.

    Projections are that, unless massively expensive improvements aremade, the Aral Sea could completely disappear by about 2010.

    hard tO Fix To see why the Aral Seas uture is so uncertain, one has to look at thegeopolitics here, the politics heavily in uenced by geography and geol-ogy. The countries in this area, once controlled by the central decisionso the old Soviet Union, are now fghting over the water, truly theirli eblood in such a dry section o the world. Kazakhstan, one o the twocountries with Aral Sea shoreline, should be more prosperous than it issince its oil and gas resources are so vast. Yet it is mired in rural poverty,urban governmental corruption, and the stress o depending upon the

    Reading about the highly saline Caspian Sea and the increasingly salty Aral Sea, curious readers maywonder where the salt originally came rom. The two lowland seas were once either under or very nearthe ancient Tethys Sea, an early ocean, which contributed quite a bit o saltiness to what is now the landhere. But then where does an ocean get its salt?

    One has to go back to the in ancy o this planet to fnd the origin o the salt. The just-born Earthbegan about . billion years ago, a blob o hot rocky material, condensed rom dust and pebbles in thesolar nebula a ter the ormation o the Sun. The rock quickly began to cool and one very common kind o rock, called hydrous silicate minerals, sweated out its hydrogen and oxygen (its H O, water).

    This water gradually rose up rom all the interior rocks o the new Earth, dissolving other mineralsalong the way. The solution, already salty, collected on the sur ace in the slightly lower areas. Some o thewater was also drawn up into the atmosphere, which was still hot, then later came down as rain whenthe air cooled. The highly soluble sodium and other salts remained in the water now deepening on thesur ace. So all the salty oceans o the world came rom the frst rocks.

    THE OCEANS OF THE WORLD AND THEIR SALT

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    neighboring countries o Tajikistan and Kyrgyzstan or reshwater romrivers that pass through those countries frst. This is a recipe or signif-cant con ict.

    Uzbekistan, the other Aral Sea shoreline country, has an economystill ar too dependent on its cotton crop, and, to a lesser extent, on rice(another crop that requires huge amounts o water). Its much smalleracreage o apricots and watermelons, also irrigation dependent, havemostly vanished or lack o water. The armers are regularly moving up-stream where the river water and land are less contaminated, but thatcreates more agricultural pollution there. Uzbekistan, a poorer countrythan Kazakhstan, also accuses Tajikistan o polluting the water artherupstream and argues with Kyrgyzstan over how much o the river waterit is consuming.

    To make matters even worse, Turkmenistan is building a large res-ervoir, a lake o about 770 square miles (2,000 km 2) or its own watersecurity. Another reservoir lies at the Kazakhstan-Uzbekistan border,and the ormer country is resented by the others because it controlsmuch o the Syr River ow.

    This situation, called a water war, is compounded here by the pov-erty o the countries involved. But all dry areas o the world, including

    Arizona, New Mexico, and Southern Cali ornia, are in stri e with theirneighbors over water, too. This is a world o 6 billion people now, andcounting, all requiring drinking water and, in dry areas, yet more water togrow ood. The United Nations estimates that about 460 million peoplearound the world are already a ected by water stress and that thisnumber could increase ten old by the year 2025 i water consumption,especially in agriculture, is not reduced.

    saLinity As has been mentioned, vast tracts o land north o the Aral Sea are an oldevaporitic basin where salty soils and sands were ormed in ancient timesrom the evaporation o nearby seawater and other orces. The Aral Seais close to the edge o this very large region. And its own underlying landwas also salty to some degree when the lake ormed originally, because o the proximity o the ancient ocean, the Tethys Sea.

    But unlike the Caspian Sea, which has long been intensely saline, the Aral Sea was once only slightly brackish, testing at about nine ounces o salt per gallon (70 g/l o salt) and people drank it. Now, it is mostly un-drinkable (depending upon the location within the lake). And its wateris verging on the drastic level o 18.7 ounces o salt per gallon (140 g/lo salt), which would be saltier than the ocean itsel . Already, some 2.5to 4 million people cannot sa ely drink the Arals wateror even near-by groundwater, since it is polluted with salt and other chemicals. The

    Aral Seas water now tests as three times as salty as the United Nations

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    standard or sa e drinking water. By 2000 some 85 percent o the adja-cent land had even become too salty or agriculture. Salty water and soildo yet more damage. They create dangerous dust.

    dust

    The direct e ect on peoples health o the geological disaster that is the Aral Sea is by ar its worst result. Just as no one can sa ely drink saltyand pesticide-laden water, no one can sa ely breathe air that includessalty and pesticide-laden sand and soil particles. When a lake like thisshrinks, that is the kind o air pollution that results. Unpaved roads andovergrazed arm felds add even more fne dust to the air.

    The shriveled shoreland that once was under the Aral Sea eatureslarge white salt pans, and some o the sur ace salt is swept up into the air.These at areas look like the oor o Death Valley, Cali ornia, and stretchso ar here that, rom an airplane, they are said to look like snow. Other

    areas, primarily dust, look a smudgy brown, as can be seen in the colorinsert on page C-2. All this toxic dust becomes regularly airborne, and the desert winds

    and low levels o precipitation here make the problem even worse. It isestimated that about 43 million tons o dust a year clog the air around the

    Aral Sea, the highest volume anywhere on the planet. About fve times a year, dust storms rage so intensely that people

    must remain inside their homes or days at a time. There the air is a bitclearer. When they emerge, it is to shovel the toxic dust o the felds,outside the ront door, and anywhere else they have the strength to do so.The inhaled dust has been ound to contain particles o pesticides, ertil-izers, cadmium, and other heavy metals not ft or human lungs.

    heaLth eFFectsHealth is very poor around the Aral Sea. Asthma, childhood pneumonia,diarrhea, kidney disease, esophageal cancer, along with anemia and tuber-culosis at the highest rates in the world, all are well above expected levelsin both children and adults in the Aral Sea area. In ant mortality is high,as is emotional stress.

    One researcher set up dust traps, ftted a pump to pull air acrossa flter to imitate a persons lungs drawing breath, and discovered theintake o dust to be our to fve times greater than the United StatesEnvironmental Protection Agency guidelines or the dusty seasonin this country. The situation is the worst on the south side o the

    Aral Sea.More than 100,000 people have already le t the Aral area or good,

    and they tend to be the healthier ones who eel able to start a new li eelsewhere. Though poverty contributes to the disease load, its origin isthe air. And that air is a direct result o the lakes shrinkage.

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    What can Be dOneThough the Aral Sea began shrinking in 1960, the tragedy was gradual.

    And the Soviet Unions government rarely allowed any outside observersanywhere within its borders. It took until 198687 or the situation hereto be recognized at all, and it was not well known until a ew years a ter

    that. International and local e orts to begin help date back just to 1990.The countries that surround the Aral are now, and have always been, toopoor to pay or the major improvements they need.

    Among the key actions suggested have been: lining the irrigationditches to ensure that the channeled river water at least reaches thecrops, installing better drinking water treatment and medical care or thepeople, paving the roads and treating the industrial wastes to cut downon the dust, and switching agricultural production rom cotton and riceto wheat and maize (which require less water). Population growth shouldalso receive immediate attention, since it is projected to rise by about

    one-third over the next 25 years.Many studies have been done on the Aral Sea and its environs. Anold saying apparently popular here goes like this: I everyone who cameto study our problem had brought a bucket o water, the Aral Sea wouldbe ull again.

    Ideas have come and gone; many international groups have simply givenup or lack o money, and at least one bizarre solution has been abandoned.That was to build a new river channel to direct Arctic Ocean water downto here. (This would just substitute a new northern problem or this one.)Few people, i any, seem to think this lake can ever refll to its 1960 size.

    One group still working hard in the Aral Sea area is Doctors WithoutBorders, physicians rom around the world (especially Western countries)who do studies, equip laboratories, help raise unds or local medical sup-plies, and train local health care workers. They collect and maintain sta-tistics on the human geotragedy at the Aral.

    Many other researchers have come up with plans to raise money orimprovements. Some o them employ taxation: taxing water use, saltdischarges, and waste ul irrigation practices, and taxing even the increasein local profts i the international community pays or new industrialacilities and other improvements. Still others recommend that Aral Seacountries trade water or electricity among themselves. This would avoidthe building o reservoirs by all the various competing countries (to makeelectricity, water must usually be dammed up to create enough orce topush it through a turbine). Problems in cooperation among the countriesand in unding, however, remain. It is not clear what will happen here.

    in the FieLd: sateLLite imaGery Earth scientists are among the researchers who have ound the basic, im-portant in ormation needed on the Aral Sea. One technique they have

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    used is satellite imagery. Satellite photos and heat sensors can establishboth the water levels and water temperatures o the Aral and how theyare changing. Among the fndings is that, as the lake has shrunk, sum-mer in the area has become hotter and winter colder, by several degrees.Using a di erent satellite, one that looks or data on the magnetism o areas it passes over, other geologists have seen that the geologic aultunder the Ural Mountains may extend south to the middle o the AralSea. This would create the potential or earthquakes in certain areas anda ect what should be built there. Another team has used soil samples todiscover where the worst o the dust storms originate.

    The Aral Sea is a living warning o what can happen when a lakeswater quality issues are ignored. Low in elevation, salty, hot, unhealthy,and an object o stri e among the countries around it, this lake is shrinkingand may well disappear entirely.

    This immense body o water, ar larger than the Aral Sea and larger even than the Caspian Sea, is not,however, a lake. It is connected to the Mediterranean Sea through the Straits o Bosporus (once an oldriver valley) at the city o Istanbul, Turkey.

    The Black Sea is also bordered by Georgia, Russia, Ukraine, Romania, and Bulgaria and is consideredto be part Europe and part Middle East. Its major contributing rivers are the Dnieper, the Danube, andthe Don, and its major mountain range the Caucasus on its east coast. Along the south coast grows theworlds biggest crop o hazelnuts.

    The wild carp, ancestor o all the species o carp now ound in the reshwater lakes and rivers o theworld, originated as a species in the Black Sea, Caspian Sea, and Aral Sea. The sh spread, evolving allthe way, to China, Germany, and Siberia. A ter that, humans imported it to extend its range elsewhere.It is now common in the United States and in many other places around the world.

    Some people love this sh. The Japanese have bred a species called the colored carp and nicknamedit the swimming fower. Other people consider it unpleasant.

    THE BLACK SEA AND THE ORIGIN OF THE CARP

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    Lake superior North America

    t his is the largest freshwater lake in the world, an expanse of blue thatlooks almost as wide as the sky itself. Lake Superior holds about 10percent of the planets entire supply of surface freshwateran estimated

    2,860 cubic miles (11,921 km 3) of it, enough to equal the water of theother three Great Lakes, plus three Lake Eries, combined. It stretchesover nearly 32,000 square miles (82,880 km 2). A ship traversing this lakeeast to west, its longest dimension, travels 376 miles (605 km) from Du-luth, Minnesota (the westernmost point of all the Great Lakes), to SaultSte. Marie, the city astride the United StatesCanada border, whereLake Superior meets Lake Huron at its easternmost point. Its expansefrom north to south is 160 miles (258 km) at the widest point. The lakehas 1,026 miles (1,651 km) of shoreline and is the highest of the GreatLakes in elevation, at 602 feet (183.5 m) above sea level.

    Bordered by Minnesota, the Canadian province of Ontario, Michi-gan, and Wisconsin, Lake Superior is the most northerly of the GreatLakes. Water temperatures average 39 to 40F (4C) year round. This iscold enough to kill an unprotected swimmer in about 20 minutes, evenin summertime (unless it is possible to make it back to a warmer, shallowcove by the shore).

    In the fall, when the air temperature around Lake Superior drops,the lake gradually loses its heat. This means it can release enough heatin one day to equal all the energy consumed in the United States inone year.

    Winter means ice. Lake Superior freezes over enough of its surfaceto stop major ship travel, but there are almost always some open areas,called polynas, where currents stir the water enough to keep ice fromforming. In 1979, an unusually cold year, its entire surface froze over,for a few hours.

    By early spring ice caves appear along its North Shore. Created byslushy water surges and surf that pile up and refreeze, some of thesecaves can seat a dozen people inside on ice block chairs. Many of these

    G 0

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    seasonal caves are large enough or a brie two-person picnic, re rigera-tion no extra charge.

    In summer, when Lake Superior can warm up to 45F (7C), it stillserves as a kind o air conditioner or people living close to its shores.In Duluth, or example, almost no one owns an ordinary air conditioner,

    though along the south shore, and occasionally on the north, people dowade into Lake Superior on hot days to cool o .

    depth and tidesThis lake plunges to 1,330 eet (405 m) deep. Because o this depth, itchurns up violent storms, especially in November be ore it reezes, andis known as the graveyard o ships. The Edmund Fitzgerald, subjecto olk songs and other lore, is the most amous example. But hundredso other large ore ships lie on its bottom, everything preserved in coldstorage. Power ul underwater currents sweep the sand o some wrecks

    every year and bury others anew. Except in those places and times, thelake is extremely clear. You can see 65 to 75 eet (20 to 23 m) downmuch o the time.

    Scuba divers, outftted in tightly ftting gear or warmth, visit someo the underwater wrecks in summertime, as well as the underwater seacaves. They avoid the temporary benthic storms that can roil the watereven on the bottom, like submerged thunderstorms. Kayakers go out insummer, too, usually remaining close to the shoreline or among islandarchipelagoes. A ew people have kayaked all around the lake, bravingwinds that could smash them quickly into the boulders on the shore.

    Lake Superior does have a tide, since tides are created by the Moonsgravity tugging on the Earths bodies o water. But, since this lake issmallcompared to an oceanthe largest di erence between low tideand high tide is less than an inch, unnoticed.

    More dramatic are the seiches, giant-scale sloshes o water. A seichecan make the lake suddenly up to 12 inches (30.5 cm) deeper across vastareas than it was just an hour be ore. These water movements are cre-ated as though the lake were a co ee cup tilting back and orth. Themovement begins in storms ar away. Storms arrive with low barometricpressure, and this means that the atmosphere is pressing down less hardon the lake where the storm is than the atmosphere would ordinarily do.

    With less pressure pressing down, the lake level rises in that area. I thestorm is large and situated over one end o the lake, and the water thererises, that lowers the water elsewhere on the lake and the sloshing begins.Then it sloshes back making the water much deeper. The e ect arrivesinvisibly (the storm is at the other end o the lake) and vanishes invis-ibly. A seiche lasts anywhere rom several hours up to 24 hours. (In LakeMichigan, where swimming is common, swimmers fnd them un.)

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    Split Rock lighthouse sits high on a headland of Lake Superiors North Shore.(www.shutterstock.com)

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    WatershedLake Superior is fed by rivers much too numerous to mention, and theydrain massive amounts of rain and snowmelt into the lake, adding to thelarge volume of precipitation that falls on it directly. Especially on theNorth Shore, many of the rivers originate in wild peat lands and traverseonly forested wilderness on their way to the lake, tumbling down wa-terfalls and gradually carving gorges. Though the forest was once loggedheavily here (and some logging continues), there are still areas of borealforest (high northern woods, composed of mostly evergreens common inCanada) on the North Shore. The area is home to cliffs, evergreens, andhardwoods, all along the North Shore, as can be seen in the color inserton page C-2.

    The lakes watershed covers 525,000 square miles (1,359,743 km 2).Since Superior lies in a temperate area of the world, and north withinthat zone, temperatures are not often hot. So evaporation out of the lake

    In northern Lake Superior the Slate Islands lie about . miles ( 0 km) o the Canadian North Shore. Thisarchipelago was created by the impact o a giant meteorite, about 0 million years ago. No one wasnear because people did not yet exist. Neither did any o the land animals here today. Not even the lakeitsel was here.

    This ancient disaster le t a complex crater, now surrounded and partly submerged by Lake Superi-ors waters. Its edges lie about . miles ( km) rom the center point. The largest o the Slate Islands isabout . miles ( km) in diameter. Though this impact site is certainly large, it was once larger, probably to 0 miles ( 0 to km) across. Erosion, rom wave action during storms, has gradually worn away

    at the islands rock mass.Scientists know that a meteorite smashed here since its orce shocked and then heated the rock

    already there, creating some new rocks with glassy intrusions and shattered ragments within them.These rocks are called breccias and tektites. It also exposed some ancient rock, about billion years old,that would otherwise have remained buried.

    Today the Slate Islands are home to hundreds o woodland caribou, sa e here rom the wolves.Though they are wild animals, they have become so una raid o humans over so many generations, thatthey will sometimes eat a carrot out o a persons hand.

    In addition to woodland caribou, the North Shore o Lake Superior is rich in other wildli e such aswolves, black bears, coyotes, moose, beaver, deer, muskrats, bobcats, some lynx, skunks, fshers, ox,raccoons, squirrels, and chipmunks. Woodland creatures are able to hide easily and tend to be shy o people. One could hike all 00 miles ( km) o the beauti ul trails on the North Shore section o the lakein Minnesota and see only a ew deer, perhaps a moose, and, o course, the squirrels and chipmunks. Thisis not a dangerous place unless you try to go swimming in the cold water.

    There are also many birds here. In act the North Shore is one o the major bird actories o thecountry. More than 0 di erent species nest in Lake Superiors woods. A springtime trip with binocularscan mean seeing 0 species in a day.

    SLATE ISLANDS

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    is less than new water into the lake. La