Study of the Earth

STUDY OF THE EARTHRE AD I N GS N GEOLOGIG ACiSC 1 ENCE 1 edited by }?if'

UNIVERSITYOF FLORIDALIBRARIES

STUDY OF THE EARTH

PRENTICE-HALL INTERNATIONAL, INC.London • Tokyo • Sydney • Paris PRENTICE-HALL OF CANADA, LTD. PRENTICE-HALL DE MEXICO, S.A.

STUDY OF THE EARTH • READINGS IN GEOLOGICAL SCIENCE Edited by }. F. WHITE Department of Earth Sciences Antioch College Yellow Springs, OhioPrentice-Hall, Inc. englewood cliffs, n.j.

© 1962 by Prentice-Hall, Inc.Englewood CMs, N.J.NoAll rights reserved. part of thisbook may be reproduced in any form,by mimeograph or any other means,without permission in writing fromthe publishers.Library of Congress Catalog Card No.: 62-8547Printed in the United States of America8589S-CSecond printing February, 1963

Preface Study of the Earth brings together outstanding readings that are par-ticularly suited to an introduction to geology and related fields. Suchreadings, although educationally useful, are usually not available. The scope of this volume is broad, and should open up new vistas formost readers. It does not restrict the study of the earth to narrow special-izations, but helps make clear the unity and the wide range of problemsthat constitute geological science. The readings offer the following advantages: 1) Stimulating articles, which might not otherwise be accessible, areconveniently at hand. The book may be used as a basic text or as asupplement. 2) \"Independent study\" can be emphasized. In addition to valuablereading, the articles can be the basis for informed discussion, short reports,and lengthier papers. They also provide a point of departure for projectsinvolving further independent study and research. 3) The reader is introduced to scientific literature and becomes ac-quainted with distinguished scientists through their contributions. This, inturn, tends to stimulate more reading of scientific literature. 4) The volume is designed to help the reader gain more meaning, inter-est, and perspective from his study of science. Terminology and descriptionare subordinated to an awareness of the significant problems. Recent re-search and present problems are emphasized, but a historical setting is alsogiven. 5) The readings are at various levels. This is an advantage, for it pro-vides a challenge to even the most well-informed reader. The book doesnot contain highly popularized and overly-simplified material. 6) The volume offers a freshness of approach and readability oftenlacking in the usual introductory book. I wish to express my appreciation to the many authors and publisherswho have permitted inclusion of their material. For the purposes of uni-formity of style, minor modifications have been made, including thedeletion of some illustrations. Unfortunately, all aspects of earth science,including many excellent papers, could not be included. F. W. J.

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ContentsINTRODUCTION The Study of the Earth, /. F. White • 1THE LAW OF UNIFORMITY AND GEOLOGIC TIMEJames Button, Karl Von Zittel • 1 1 The Uniformity of Nature, CharlesCoulston Gillispie • 18 Measuring Geologic Time, Adolph Knopf • 41THE EARTH MODEL PROBLEMS AND IMPLICATIONSThe Interior of the Earth as Revealed by Earthquakes, I. Lehmann • 63AMSOCThe Radioactive Earth, Patrick M. Hurley • 73 The Hole tothe Earth's Mantle, H. H. Hess • 79CRUSTAL FEATURES AND PROCESSESThe Crust, /. Tuzo Wilson • 89 Instability of Sea Level, Richard J.Russell • 105 Questions of the Coral Reefs, Norman D. Newell • 121How Volcanoes Grow, /. P. Eaton and K. J. Murata * 137 CoesiteCraters and Space Geology, W. T. Pecora • 164 The Stratigraphic Pan-orama, Hollis D. Hedberg • 171PAST CLIMATES AND DRIFTING CONTINENTSA Theory of Ice Ages, Maurice Ewing and William L. Bonn '203 ATheory of Ice Ages II, Maurice Ewing and William L. Bonn '111 Car-bon Dioxide and the Climate, Gilbert N. Plass • 224 The Record ofClimatic Changes as Revealed by Vertebrate Paleocology, Edwin H. Col-bert • 239 Bearing of Forests on the Theory of Continental Drift, Br.Ralph W. Chancy • 260 Rock Magnetism, S. K. Runcorn • 111

viii CONTENTSTHE HISTORY OF LIFEThe Course of Evolution, George Gaylord Simpson '291 Theories ofEvolution, George Gaylord Simpson • 301 Origin of the Amniote Egg,Alfred S. Romer 'BIO Origin of the Pacific Island Molluscan Fauna,Harry S. Ladd • 321 Origin of Life, Elso S. Barghoorn * 335ORIGIN AND EVOLUTION OF THE EARTH The Origin of Continents, Mountain Ranges, and Ocean Basins, George C. Kennedy • 349 Development of the Hydrosphere and Atmosphere, with special reference to probable composition of the early atmosphere, William W. Rubey • 363 The Origin of the Earth, Harold C. Urey • 386A.PPENDIXThe Geologic Time Scale • 403 Selected References • 404Biographic Notes • 405 Glossary of Selected Terms • 406

INTRODUCTION —What stuft 'tis made of, whereof it is born, ^^^ *o learn. . . . Shakespeare, The Merchant of Venice, Act I, sc. IThe Study of the Earth • J. F. WHITE\". . . the nature and system of the world have been discovered but lately. . . .\" — VLucretius, De Rerum Natura, (100-55 b.c.)IT IS DIFFICULT TO PROVIDE A BRIEF BUT MEANING-ful introduction to a topic as broad as the study of the earth. Thisintroduction is meant to provide a framework to the study of geo-logical science: specifically its broader outlines, its importance, andits relationship to other fields of knowledge. The significance of theselections will be immediately apparent. Man has always contemplated his world and has sought explana-tions of how the earth began and how its various features wereformed. Although many of his earlier explanations now seem fanci-ful, they served the needs of the time and seemed to explain satis-factorily the data at hand. The early Greeks viewed nature as a sub-ject worthy of philosophical speculation; many of their views stillhave an essentially modern outlook. However, it is only since theeighteenth century that the study of the earth has developed sys-tematically through the collection of verifiable data and the build-ing of scientific theories. Our most recent theories, which attempt toexplain not only past findings but also current data, remain \"true\"until even more modern theories are developed to replace them.Past and presentAlthough we have greatly enlarged our understanding of the earth,we neither pretend nor expect to know all the answers. Indeed, muchof the increased understanding has only led to new questions, and itWemay well be that learning has no end. find that the earth still 1

2 J. F. WHITEpresents an enormous variety of problems, both large and small, ofWethe present and of the past. would like to better understand thelarge and small processes currently at work on and within the earth,and to know more about the present composition and structure ofour planet. In addition, there are problems of the past which demandour investigation, including the process of evolution from more primi-tive forms. We have reason to believe that the earth has been undergoing along and complex development, proceeding from a comparativelyhomogeneous and simple structure to one much more complex. Somefive billion years ago, there was only a cloud of matter in the form ofdust and gas. Later, an earth gradually evolved, and still later oceans,continents, and a primitive atmosphere formed. The first lifelikestructure gradually developed, eons ago, from comparatively complexminerals. And a human animal appeared only an instant ago ingeologic time, the improbable product of an incredibly long sequenceof ancestral events which began with the appropriate-sized cloud ata certain distance from a star. Such are the broad but imperfectlyunderstood outlines of the modern evolutionary view of the world,much of whose development has come through study of the earth. We are concerned, thus, with the past, present, and continuingdevelopment of our planet. This includes its scenery, minerals, conti-nents, oceans, atmosphere, internal nature, and life. None of thesefactors can be isolated, for even the origin of life has had profoundeffects on the composition of the atmosphere and the nature of theearth's surface. The study of the earth involves not only events andprocesses which we observe now, but also those acting through longWeperiods of time. cannot separate the past from the present, andthe present becomes understandable only in relation to the past.Importance of study of the earth For a better understanding of the environment of which we are apart, we must study the earth, if only to cope with, control, andintelligently manage it. It may be surprising that we know relativelyAlittle about the nature of our environment. more complete under-standing of the earth may be a matter of survival, since there is nonecessity in the scheme of things that the human species survive. The unknown. It has been said that we know even less aboutthe surface of our own planet than we do of the moon, primarily

THE STUDY OF THE EARTH 3because of our inadequate knowledge of the vast area underlyingthe oceans. Exploration through an average depth of 12,000 feet ofwater is difficult, and only in recent years have we begun to makereal progress in our investigation of the oceans and the land beneaththem.Official photograph, U.S.Navy, Sept. 12,1952Volcanoes such as Bar-cena (RevillagigedoIslands, Mexico) sym-bolize the internalenergy of the earth. Vol-canic activity appears tobe a main process in theorigin and evolution ofthe oceans, atmosphere,and lands.On the lands we can easily collect rock samples for study, butWewhat of the rock material beneath the oceans? know this materialis different from the granitic rocks of which continents are made.But as little as we know of the thin film of materials forming theouter surface of the earth, we know even less about the much greatermass of the inner earth. For knowledge of this interior we have hadto depend on indirect observations, such as the behavior of earth-Wequake waves passing through the earth's interior. further assumethat the earth's internal matter is similar to the meteoritic materialcoming from outer space. Clearly, an improved understanding of theinterior of the earth is fundamental to our understanding of theearth's processes, properties, and origin. Since the earth is large, the number of questions that may beasked about its nature is correspondingly large. Do the continentsand ocean basins remain fixed in their positions with respect to theequator and poles, or do the continents drift about over the face ofthe earth? What is the explanation of the large climatic changesthat have taken place in the past; why did regions now on or nearthe equator once possess glaciers of continental extent? Do certain

Photo from the Barringer Crater Company A visitor from outer space, not a nuclear ex- plosion, created this im- pressive crater, which is about one mile across. ^> Studies of meteorites and their craters have given us valuable clues to the nature and com- position of the earth and other planets.of the large fracture systems of the earth provide evidence for thehypothesis of an expanding earth? What minerals are present underthe ultra pressures and high temperatures of the interior of theearth?In addition to these, one of the oldest of questions still lacks aHowdefinite answer: old is the earth? Our present calculations indi-cate an age of 4.5 x 10^ years or 4 billion, 500 million years. Anothertime-problem is the construction of an accurate calendar for theWhenearth in order to correctly place and interpret past events. didlife appear, and how long has it taken for the various forms to evolve?What was the earliest life, and under what conditions did it originate?How swiftly did the oceans and the atmosphere form, and are theystill forming? Progress in solving the problems of dating the past willhelp develop answers to these questions, and in the future, moreknowledge, better theories, and new questions will allow us to im-prove our picture of the entire earth system. Modern thought. In the recent past, intellectuals as well as thecommon man had what now seem rather strange beliefs concerningthe history and origin of their surroundings. For example, if menof the eighteenth century saw the Grand Canyon and wonderedabout its origin, they would picture a sudden, violent tearing apartof the earth's crust, a catastrophic or supernatural event during whichthe canyon was created. In fact, every feature of the world wasthought to have formed suddenly by such means. Former beliefsconcerning the records of past life were equally unusual. Some thoughtfossils were created by emanations from the stars; others thought

THE STUDY OF THE EARTH 5Courtesy of the BuffaloMuseum of Science andIrving ReimannAncient but complexlife is shown by thistrilobite, a marine ani-mal of about 350 millionAyears ago. restorationof Terataspis whichlived on Devonian coralreef near Williamsville,New York.they were the remains of hfe present before the time of the \"GreatFlood\" and Noah's ark. It is apparent that men in the recent past viewed the earth fardifferently than we do today. This was due, not to any lack ofreasoning, but to different fundamental assumptions or beliefs. Therewas no concept of change except by rapid and catastrophic or super-natural means. Once created, the earth and its life were viewed asunchanging and static, comparable to a giant mechanical clock thatwas made and set in motion by its creator some few thousand yearsago. With the discovery of geologic time, time of unimaginable extent,and the clear formulation of the concept of uniformity (natural lawis constant in time), the old views were no longer reasonable or evenbelievable. In place of the static, young, and suddenly created earthand life, the revolutionary concept of a dynamic, ancient, ever-

6 J. F.WHITEchanging, and gradually developing world emerged. This revolution inthinking has not only been exceedingly significant in influencing theprogress of science, but may be the most influential factor in thedevelopment of our modern thought.Man is building, at accelerating speed, a super-bridge of knowl-Weedge reaching to the stars. can expect continued investigation ofthe earth, with its many unsolved problems, to contribute to the newknowledge that may again greatly change our view of the world.Economic implications. The inquiry into the nature of our planethas advanced not only our scientific knowledge and world view, butalso the economic welfare of man. Foremost among the applicationsof the study of the earth is the discovery and exploitation of mineralresources. It is not an exaggeration to say that our present civilizationowes its existence to the extensive use of mineral raw materials. Atthe present time, almost all of our energy requirements depend on Photo from Thermal Power Company, San Francisco Power from the earth's heat. Steam wells near San Francisco, Cal.

THE STUDY OF THE EARTH 7the fossil fuels (oil, coal, and natural gas), and, for the future, muchlarger energy resources based on radioactive elements such as uraniumAare available. further importance of minerals is that, with the ex-ception of agricultural products, almost everything we use is directlyor indirectly made from mineral raw materials. We have heard much in recent years about the population explo-sion and the terribly impoverished conditions of the large majorityof the human race in the underdeveloped regions of the world. Re-lated to these tragic facts of life is the problem of achieving a greaterproduction of minerals, including an adequate supply of water. Atthe present time our minerals are being used in enormous amountsat ever increasing rates; with the exception of underground water,most of these can be regarded as non-replenishable. In the UnitedStates, where the population has approximately doubled in the last50 years, the production of minerals has increased more than 800per cent. If the economically backward areas are to be developed,and if population continues to grow at the present rate, the problemof exhaustion of known mineral resources seems to be merely a ques-tion of a short period of time. Research leading to a better knowledgeof the occurrence and use of minerals is imperative if we are to solvethese problems. Today, about 95 per cent of the world's people live on approxi-mately 25 per cent of the land. If we consider the lack of resourcesand the dense, growing populations, we see that this populationdistribution will need to be altered in the near future. Factors of un-favorable climate, rugged terrain, and poor soils are chiefly responsiblefor the present limited use of land areas. It seems clear that greateruse can be made of our potential resources, if the appropriate researchis done. It is possible that further investigation of climate, includingincreased knowledge of past climatic changes, may allow us to alterclimates—even to increase the amount of rain in a desert region.Relationships to other fields Splitting knowledge into distinct and separate fields is artificial andarbitrary, for there are no sharp lines dividing man's knowledge. Thestudy of the earth encompasses geological and other earth sciences(such as oceanography, meteorology, and geography) which are re-lated intimately to one another and also closely connected to othersciences. But the earth is only a part of a much larger complex—thesolar system. The study of the solar system is part of astronomy, and

8 J. F.WHITE CHEMISTRY PHYSICS GEOLOGY BIOLOGY EARTH SCIENCE GEOGRAPHYASTRONOMY ENGINEERINGRelationships between fields of study.here the interests of both fields merge. The basic building blocks ofthe earth are minerals (natural crystals) composed of elements andcompounds, and chemistry as well as mineralogy began with thestudy of such mineral materials. The earth follows physical \"laws,\"and here the interests of physics and the earth sciences are oftenclosely related. The geographer is concerned with the physical environ-Howment, primarily in its relation to people. do mineral resources,soils, landforms, and climates influence population distribution, in-dustrial location, the planning of cities and regions, and the diff^erentkinds of culture? The study of past life and past environments, in-

THE STUDY OF THE EARTH 9eluding climate ehanges, drifting continents, and rising and sinkinglands, is of concern not only to geologists, climatologists, and otherearth scientists, but also to biologists and anthropologists. Study inone field frequently contributes to the solving of problems in another.Finally, the study of the history of the earth is intrinsically related tothe subjects of written history, philosophy and religion. Although the study of the earth is related to these other fields,and often makes use of techniques and concepts first developed inthem, it has distinct and characteristic features of its own. First andof primary importance are the types of problems which constitute thefield of study, for they are concerned with the material and structuresin the earth itself. Second, the study is often of past events, proc-esses, and environments, giving the study of the past as much im-portance as the study of present conditions.



THE LAW Amid all the revolutions of the Globe, the economy of nature has been uniform and OF her laws are the only things which haveUNTFOR MTTY resisted the general movement. The rivers and the rocks, the seas and the continents , xTp. have been changed in all their parts; but the laws which direct those changes, and the(jiiOLCjCjilC —rules to which they are subject, have TIME remained invariably the same. playfair, Illustrations of the Huttonian Theory (1803) James Hutton • KARL VON ZITTELAT A TIME WHEN WERNER WAS IN THE ZENITH OF HISfame, during those seventies and eighties of the eighteenth century whenyoung geologists were flocking to hear the wisdom from the lips of theprophet of geognosy in Freiberg, a private gentleman, living quietly inEdinburgh, was deliberating and writing a work on the earth's surfacethat will live for ever in the annals of geology as one of its noblest classics.* James Hutton, the author of the famous Theory of the Earth, was theson of a merchant, and was born in Edinburgh on 3rd June 1726. Hereceived an excellent education at the High School and University of hisnative city. His strong bent for chemical science induced him to selectmedicine as a profession. He studied at Edinburgh, Paris, and Leyden,and took his degree at Leyden in 1749, but on his return to Scotland hedid not follow out his profession. Having inherited an estate in Berwick-shire from his father, he went to reside there, and interested himself inagriculture and in chemical and geological pursuits. The success of an • This article is adapted from Karl von Zittel, History of Geology and Paleontology,trans. Maria M. Ogilvie-Gordon (Charles Scribner's Sons: New York, 1901), pp. 67-75.(ed.) * Abraham Gottlob Werner (1749-1817), Professor at Freiberg, was the mostfamous geologist of his time. Although he made many contributions to geology, he isremembered especially as the founder and influential teacher of the Neptunian Theory.This theory, in essence, taught that the earth originated by successive precipitationsfrom original aqueous solutions containing all the material of the earth, (ed.) 11

12 KARL VON ZITTEL industrial undertaking in which he had a share afforded him ample means, and in 1768 he retired to Edinburgh, where he lived with his three sisters.He actively engaged in scientific inquiry, and enjoyed the cultural socialintercourse open to him in Edinburgh. The literary fruits of his life in the country include several papers on meteorology and agriculture, and a large philosophical work. From his early days he had always taken a delight in studying the sur-face forms and rocks of the earth's crust, and had lost no opportunity ofextending his geological knowledge during frequent journeys in Scotland,England, in Northern France, and the Netherlands. On his tours intothe neighbourhood of Edinburgh he was often accompanied by his friends,who realised the originality of many of Hutton's views on geological sub-jects, and begged him to put them into writing. At last Hutton set him-self to the work of shaping his ideas into a coherent, comprehensiveform, and in 1785 read his paper on the \"Theory of the Earth\" beforethe Royal Society of Edinburgh. Three years later it was published inthe Transactions. The publication of the work attracted little favourable notice. This mayhave been due partly to the title, which was the same as that of so manyvalueless publications, and partly to the involved, unattractive style ofwriting; in larger measure, however, it was due to the fact that the learn-ing of the schools had no part in Hutton's work. Hutton's thoughts hadbeen borne in upon him direct from nature; for the best part of his lifehe had conned them, tossed them in his mind, tested them, and soughtrepeated confirmation in nature before he had even begun to fix them inwritten words, or cared to think of anything but his own enjoyment ofthem. Hutton's work was projected upon a plane half a century beyond therecognised geology of his own time. Hutton's audience of geologists hadto grow up under other influences than polemical discussions betweenNeptunists and Plutonists, and had to learn from Hutton himself to tapthe fountain of science at its living source. In 1793 a Dublin mineralogist, Kirwan, attacked Hutton's work inignoble terms, and the great Scotsman, now advanced in years, resolutelydetermined to revise his work and do his best by it. Valuable additionswere made, and the subject-matter brought under more skilful treatment.In 1795 the revised work appeared at Edinburgh, in independent formand in two volumes. It was his last effort. Hutton died in 1797 from aninternal disease which had overshadowed the closing years of his life. The original treatise of Hutton is divided into four parts. The first twoparts discuss the origin of rocks. The earth is described as a firm body,enveloped in a mantle of water and atmosphere, and which has beenexposed during immeasurable periods of time to constant change in itssurface conformation. The events of past geologic ages can be most

JAMES HUTTON 13satisfactorily predicted from a careful examination of present conditionsand processes. The earth's crust, as far as it is open to our investigation, islargely composed of sandstones, clays, pebble deposits, and limestonesthat have accumulated on the bed of the ocean. The limestones representthe aggregated shells and remains of marine organisms, while the otherdeposits represent fragmental material transported from the continents.In addition to these sedimentary deposits of secondary origin there areprimary rocks, such as granite and porphyry, which, as a rule, underlie theaqueous deposits. In earlier periods the earth presented the aspect of an immense ocean,surmounted here and there by islands and continents of primary rock.There must have been some powerful agency that converted the loosedeposits into solid rock, and elevated the consolidated sediments abovethe level of the sea to form new islands and continents. According to Hutton, this agency could only have been heat; it couldnot have been water, since the cement material (quartz, felspar, fluorine,etc.) of many sedimentary rocks is not readily soluble in water, and couldscarcely have been provided by water. On the other hand, most solidrocks are intermingled with siliceous, bituminous, or other material whichmay be melted under the influence of heat. This suggested to Hutton histheory that at a certain depth the sedimentary deposits are melted by theheat to which they are subjected, but that the tremendous weight of thesuperincumbent water causes the mineral elements to consolidate oncemore into coherent rock-masses. He applied this theory of the meltingand subsequent consolidation of rock-material universally, to all pelagicand terrestrial sediments. In the third part it is shown that the present land areas of the globeare composed of rock-strata which have consolidated during past ages inthe bed of the ocean. These are said to have been pushed upward by theexpansive force of heat, while the strata have been bent and tilted duringthe upheaval. Hutton next describes the occurrence of crust-fissures bothduring the consolidation of the rock and during the elevation of largeareas, and the subsequent inrush of molten rock or mineral ores into thefissures. He regards volcanoes as safety-valves during upheaval, which byaffording exit at the surface for the molten rock-magma and superheatedvapours prevent the expansive forces from raising the continents too far. The evidences of volcanic eruption in the older geological epochs arenext discussed. Hutton expresses the opinion that during the earlier erup-tions the molten rock-material spread out between the accumulated sedi-ments or filled crust-fissures, but did not actually escape at the surface;consequently, that the older rock-magmas had solidified at great depthsin the crust and under enormous pressure of superincumbent rocks. Hecalls the older eruptive rocks \"subterraneous lavas,\" and includes amongstthem porphyry and the whinstones (eq. trap-rock, greenstone, basalt,

14 KARL VON ZITTELwacke, amygdaloidal rocks); granite was also added in a later treatise.Hutton points out that the subterraneous lavas have a crystalline structure,whereas those that solidify at the surface have a slaggy or vesicularstructure. In the fourth part, Hutton concentrates attention on the pre-existenceof older continents and islands from which the materials composing morerecent land areas must have been derived. He likewise discusses the evi-dences of pre-existing pelagic, littoral, and terrestrial faunas from whichexisting faunas must have sprung. But, he continues, the existence ofancient faunas assumes an abundant vegetation, and direct evidence ofextinct floras is presented in the coal and bituminous deposits of theCarboniferous and other epochs. Other evidence is afforded in the silicifiedtrunks of trees that occasionally are found in marine deposits, and haveclearly been swept into the sea from adjacent lands. Hutton then sets forth, in passages that have become classic in geologi-cal science, the slow processes of the subaerial denudation of land-surfaces.He describes the effects of atmospheric weathering, of chemical decom-position of the rocks, of their demolition by various causes, and the con-stant attrition of the soil by the chemical and mechanical action of water.He elucidates with convincing clearness the destructive physical, chemical,and mechanical agencies that effect the dissolution of rocks, the work ofrunning water in transporting the worn material from the land to theocean, the steady subsidence of coarser and finer detritus that goes on inseas and oceans, lakes and rivers, and the slow accumulation of thedeposits to form rock-strata. Hutton impresses upon his readers the vast-ness of the geological aeons necessary for the completion of any suchcycle of destruction and construction. In proof of this, he calls attentionto the comparative insignificance of any changes that have taken place inthe surface conformation of the globe within historic time. Hutton was thus the great founder of physical and dynamical geology;he for the first time established the essential correlation in the processesof denudation and deposition; he showed how, in proportion as an oldcontinent is worn away, the materials for a new continent are being pro-vided, how the deposits rise anew from the bed of the ocean, and anotherland replaces the old in the eternal economy of nature. The outcome ofHutton's argument is expressed in his words \"that we find no vestige ofa beginning,—no prospect of an end.\" When we compare Hutton's theory of the earth's structure with thatof Werner and other contemporary or older writers, the great featurewhich distinguishes it and marks its superiority is the strict inductivemethod applied throughout. Every conclusion is based upon observeddata that are carefully enumerated, no supernatural or unknown forcesare resorted to, and the events and changes of past epochs are explainedfrom analogy with the phenomena of the present age.

JAMES HUTTON 15 The undeveloped state of physics and chemistry in the time of Huttoncertainly gave rise to several errors in connection with the origin ofminerals and rocks. No geologist now would agree with the principle thatheat has hardened and partially melted all sedimentary rocks, and just aslittle would he ascribe to heat the origin of flint, agate, silicified wood,etc. On the other hand, the recognised hypothesis of regional metamor-phism of the crystalline schists is an extension of Hutton's conception ofthe action of heat and pressure upon rocks. Hutton was the first to demonstrate the connection of eruptive veinsand dykes with deeper-seated eruptive masses of granite, and the first topoint out the differences of structure between superficial lavas and moltenrock solidified under great pressure. In assuming that granite representsrock consolidated from a molten magma, Hutton laid the foundationof the doctrines of Plutonism as opposed to those of Neptunism. Again, no one before Hutton had demonstrated so effectively and con-clusively that geology had to reckon with immeasurably long epochs, andthat natural forces which may appear small can, if they act during longperiods of time, produce effects just as great as those that result fromsudden catastrophes of short duration. Hutton's explanation of the uprising of continents, owing to the expan-sive force of the subterranean heat, was not altogether new, nor was itsatisfactory. Neither had Hutton any clear conception of the significanceof fossils as affording evidence of a gradual evolution in creation. Yet inspite of these disadvantages, Hutton's Theory of the Earth is one of themasterpieces in the history of geology. Many of his ideas have beenadopted and extended by later geologists, more particularly by CharlesLyell, and form the very groundwork of modern geology. Hutton's geniusfirst gave to geology the conception of calm, inexorable nature workinglittle by little—by the raindrop, by the stream, by insidious decay, byslow waste, by the life and death of all organised creatures,—and eventu-ally accomplishing surface transformations on a scale more gigantic thanwas ever imagined in the philosophy of the ancients or the learning ofthe Schools. And it is not too much to say that the Huttonian principleof the value of small increments of change has had a beneficial, sugges-tive, and far-reaching influence not only on geology but on all the naturalsciences. The generation after Hutton applied it to palaeontology, andthus paved the way for Darwin's still broader, biological conceptionsupon the same basis. Hutton's scientific spirit and genial personality won for him many friendsand adherents amongst the members of the Edinburgh academy. Themost distinguished of these were Sir James Hall and the mathematician John Playfair. Hall (1762-1831) contested the validity of the opinion heldby some of Hutton's opponents, that the melting of crystalline rockswould only yield amorphous glassy masses. Hall followed experimental

16 KARL VON ZITTELmethods; he selected different varieties of ancient basalt and lavas fromVesuvius and Etna, reduced them to a molten state, and allowed them tocool. At first he arrived only at negative results, as vitreous masses wereproduced; but he then retarded the process of cooling, and actually suc-ceeded in obtaining solid, crystalline rock-material [Nicholson's Journal,No. 38, 1800). By regulating the temperature and the time allowed forthe cooling and consolidation. Hall could produce rocks varying fromfinely to coarsely crystalline structure. And he therefore proved that undercertain conditions crystalline rock could, as Hutton had said, be pro-duced by the cooling of molten rock-magma. Hall then put to the testHutton's further hypothesis, that limestone also was melted and re-crystallised in nature. To this hypothesis the objection had been madethat the carbonic acid gas must escape if limestone were brought to aglowing heat, and the material would be converted into quicklime. Thiswas Hall's first experience; then he devised another experiment. He intro-duced chalk or powdered limestone into porcelain tubes or barrels, sealedthem, and brought them to a very high temperature. The carbon dioxidegas could not escape under these conditions. The calcareous material wasthus subjected to the enormous pressure of the imprisoned air, and car-bonic acid was converted under this pressure into a granular substanceresembhng marble. Hall calculated from a series of successful experimentsthat a pressure equivalent to fifty-two atmospheres, or to a depth of sea-water 1,700 feet below sea-level, was necessary for the production of solidlimestone, 3000 feet of depth for that of marble, and 5,700 feet of depthin order to reduce carbonate of lime to a molten state. These results were afterwards confirmed by other experimentalists. ThusWerner's theorv that cr\'stalline rock represented in all cases a precipitatefrom water was shown to be inadequate, and it was incontestably provedthat crystalline rock might originate from molten rock when slowly cooledunder pressure. Hall also conducted experiments on the bending and folding of rocks.He spread out alternate horizontal layers of cloth and clay, placed a weightupon them, and subjected them to strong lateral pressure. These andsimilar experiments have been often repeated within recent years, and itis well known that in this way phenomena of deformation can be arti-ficially produced which bear the closest resemblance to the phenomenaof rock-deformation under natural conditions. Hall, in his desire to vindicate Hutton's theory, became himself one ofthe great founders of experimental geology. At the same time, John Play-fair,^ whose interest in geology had been roused by Hutton's companion-ship, became the enthusiastic exponent of Hutton's theory.bom^ John Playfair, 1748, in Bervie, Forfarshire, son of a minister, showed in hisearly years a remarkable genius for mathematics. He studied in Aberdeen and Edinburgh,in 1773 became minister in Bervie, in 1785 Professor of Mathematics in the University

JAMES HUTTON 17 It was Playfair's literary skill that opened the eyes of scientific men tothe heritage Hutton had left for them. He did for Hutton's teaching whatfifty years after was done for Darwin's doctrines by the gifted Huxley. Thebrilliant exponent and successful combatant, no less than the deep stu-dent and enlightened thinker, is required to establish a new system ofthought, for such a system is always bound to be in a measure reactionaryto older doctrines that have received the stamp of usage and authority. Playfair's Illustration of the Huttonian Theory (1802) is a lucid exposi-tion of the theory in the form of twenty-six ample discussive notes. Play-fair's work differs in no essential point from the views held by his masterand friend, but many subjects which receive a subordinate treatment inthe Theory of the Earth are brought into prominence by Playfair, andplaced for the first time on a firm scientific basis. Among the subjects fully discussed are the uprise and bending of strata,the origin of crystalline rocks at low horizons of the crust and under verygreat pressure, and the occurrence of granite as dykes in various Britishlocalities. His treatment of valley and lake erosion is extremely able.And Playfair was the first geologist who realised that the huge erraticblocks might have been carried to their present position by former glaciers.His insight in this respect would alone have won for him a lasting fame,for the erratics on Alpine slopes and plains had long been observed bygeologists and an explanation vainly sought. Playfair also studied theraised beaches on the coast-line of Scotland, and rightly concluded thatthey afforded evidence of an actual uprise of the land, in opposition tothe views of Linnaeus and Celsius, who had explained a similar series ofphenomena in Sweden as a result of the retreat of the ocean. Playfair gavethe first complete account of the evidences of oscillations of level inEuropean lands. Playfair's style is a model of clearness and precision, and his argumentsare always thoroughly logical, and in agreement with physical laws. HisHuttonian Theory was translated into French by C. A. Basset in 1815.of Edinburgh, and twenty years after Professor of Philosophy in the same University.Led by Hutton into the study of geology, he devoted his holidays to geological toursthroughout Great Britain and Ireland, and in 1815 and 1816 made longer tours toAuvergne, Switzerland, and Italy; he died in 1819 in Edinburgh.

The Uniformity of Nature • CHARLES COULSTON GILLISPIEWe now propose to examine those changes which still take place on our globe,investigating the causes which continue to operate on its surface. . . Thisportion of the history of the earth is so much the more important, as it hasbeen long considered possible to explain the more ancient revolutions on itssurface by means of these still existing causes. . . But we shall presently seethat unfortunately this is not the case in physical history; the thread of opera-tions is here broken, the march of nature is changed, and none of the agentsthat she now employs were sufficient for the production of her ancient works.* —Georges Cuvier ^When we are unable to explain the monuments of past changes, it is alwaysmore probable that the difference arises from our ignorance of all the existingagents, or all their possible effects in an indefinite lapse of time, than thatsome cause was formerly in operation which has ceased to act. . .Our estimate, indeed, of the value of all geological evidence, and the interestderived from the investigation of the earth's history, must depend entirely onthe degree of confidence which we feel in regard to the permanency of the lawsof nature. Their immutable constancy alone can enable us to reason fromanalogy, by the strict rules of induction, respecting the events of former ages,or, by a comparison of the state of things at two distinct geological epochs,to arrive at the knowledge of general principles in the economy of our terrestrial—system. Sir Charles Lyell 2IF BUCKLAND FEARED THAT WITHOUT CATACLYSMSthere was no God, Lyell was as fundamentally apprehensive lest, withoutuniformity, there was no scienccf He could feel no reverence for a law-• From Charles Coulston Gillispie, Genesis and Geology (Cambridge, Mass.: Harvard©University Press, 1951), Chapter V. Reprinted by permission of the publishers. ThePresident and Fellows of Harvard College.* Georges Cuvier (1769-1832), the founder of vertebrate paleontology and compara-tive anatomy, was a leader of the catastrophist school. This school, dominant in theearly 19th century, saw a succession of worlds that were separated by periods whennature was not natural, but supernatural and catastrophic. The present world began afterthe Biblical flood, the universal deluge, (ed.) f William Buckland (1784-1856), one of the foremost geologists of the early 19thcentury, was a catastrophist and strong supporter of the Mosaic account of the Flood, (ed.) 18

THE UNIFORMITY OF NATURE 19giver who kept amending the constitution of nature. For some reason orother, however, the catastrophist controversy never became so acrimoniousas the Vulcanist had been. Professor Sedgwick might disagree profoundlywith Lyell—in fact, he was almost certain to—but they remained fastfriends.* Perhaps the incidental fact that the catastrophist-uniformitariandebate was carried on within the Geological Society instead of by con-flicting academies contributed to its air of scholarly good humor. Thentoo, Lyell's followers, and he with them, had once been diluviahsts andcould display a certain amused and superior tolerance for the error oftheir own past ways.One may, perhaps, deplore the disappearance of subtitles in the twen-tieth century, for it is convenient to know what a book is going to saybefore one reads it. Like Buckland in the Reliquiae, Lyell firmly staked outhis subject on the title page: Principles of Geology, Being an Attempt toExplain the Former Changes of the Earth's Surface, by Reference toCauses Now in Operation. Unlike Werner, Hutton, and Cuvier, LyellAwas more the critic than the original investigator. younger contem-\"Weporary later remarked, collect the data, and Lyell teaches us tocomprehend the meaning of them.\" ^ Even before Lyell removed the floodfrom its accepted place in geological dynamics, however, a few scientistshad begun to express reservations about its universal efficacy. Next topaleontological research, a field more popular with the diluviahsts, thephenomena of volcanic action and the structure of valleys were the sub-Ajects most interesting to geologists during this period. number of pointsbegan to seem very dubious as a result of continually extended observa-tions. In the first place, it became increasingly difficult to refer the com-mencement of all so-called alluvial deposits to a single event or even toany one period. Rivers, too, appeared in many cases to have cut theirvalleys through successive strata and through lava flows of many differentepochs, some of which were postdiluvian even by the catastrophist chro-nology. It was difficult to describe gently winding river beds as the result ofthe scouring action of a single torrent, which could more easily be sup-posed to have cut straight gorges in its violent retreat. Nor could mixturesof fresh and salt water deposits be explained as the kind of uniform suc-cession which a single flood, either salt or fresh, would have produced.Moreover, there was an increasing comprehension of the proper chrono-logical classification of \"primitive\" and \"transition\" rocks and of the vastages which must haVe elapsed between their formation. Such suggestionswere scattered, however, among a number of memoirs through which itwould be profitless to chase them. It would be even less profitable todevelop the arguments with which diluviahsts met the difficulties.'*Although these scattered objections were not pulled together into an * Adam Sedgwick (1785-1873), known principally for his work on the Paleozoic sys-tem, was a firm believer in catastrophic geology, (ed.)

20 CHARLES COULSTON GILLISPIEintegrated attack upon catastrophist assumptions in natural history untilthe publication of Principles of Geology, there were a few obscure criticswho raised strident voices of dissent in the chorus of mutual congratula-tions which Buckland had touched off among geologists. Perhaps theReverend John Fleming, a zoologist member of the Wernerian Society,set forth the closest approximation to an anticipatory statement of uni-formitarianism. He had to admit Buckland's success: This work [Reliquiae Diluvianae], like the \"Theory\" of Cuvier, has greatlycontributed to render the science of geology popular, by bringing it into favourwith the Church, and even securing the countenance of the drawing-room. Thegeneral reader has been charmed with the novel scenes which it discloses,while the Christian has hailed it with joy, as offering a valuable testimony tothe authority of revelation.^Such easy popularity was not sufficient excuse for error in the stern,Calvinist eye of the Reverend Dr. Fleming, however. For Buckland's geo-logical deluge was contradicted both by the evidence of revelation andby that of the rocks. In developing the latter objections. Dr. Fleminganticipated in outline the major points which Lyell expanded into histhree-volume Principles: the gradual excavation of river valleys; the artifi-ciality of referring \"alluvial\" detritus, whether sediment or organic remains,to a single source; the philosophic gratuitousness of supposing that a dif-ferent order of forces had ever been called into play. Oddly enoughthough—in view of the attitude uniformitarians were to profess towardssuch reasoning—it was also on the ground of Mosaic testimony that Dr.Fleming took severe exceptions to Buckland's flood. For Cuvier and Buck-land destroyed every species; Moses saved two individuals from each. Theysubstituted the antediluvian sea floor for the old land surfaces; Mosessummoned and dismissed the waters from a never-changing earth. Theydescribed a sudden, transient, and violent torrent which left marks onevery valley and gorge; Moses left word of a gentle stand of water risingplacidlv for forty days. And the true flood left no traces except a rainbow,the only empirical sign God has ever given us.^ It was chiefly, however, upon the work of George Poulett Scrope, whohad published his views in 1825 and 1826, that Lyell relied for much ofthe new factual material included in the Principles of Geology. Scrope haddevoted his descriptive talents to the investigation of extinct and activevolcanoes. His theoretical conclusions demolished the \"craters of eleva-tion\" conjured up by Werner's younger followers in their belated appre-ciation of the widespread incidence of volcanic formations. Scrope empha-sized the continuous nature of volcanic deposits, their presence in strataof every epoch, and the impossibility of classifying volcanoes accordingto whether they had been eruptive before or after a flood. Given timeenough, one could account for all lava formations by volcanic action of

THE UNIFORMITY OF NATURE 21an intensity no greater than that of the present, and Scrope exphcitlysuggested that the same thing was true of every aspect of geologicalchange/ Lyell, then, did not pull his method of interpretation out of thin air,nor single-handed revive the Huttonian attitude. In the quotation at thehead of this chapter, Cuvier remarks that \"it has long been consideredpossible to explain the more ancient revolutions ... by means of thesestill existing causes,\" and he regarded this as a doctrine which his workhad overthrown. In 1825 Constant Prevost had dared to challenge Cuvier'sauthority, though no one paid much attention to him, and between thenand 1830 he and Lyell undertook a number of extensive geological tourson the Continent, a type of journey very fashionable at the time amonglaymen as well as among scientists. Lyell's ideas seem to have formedrather suddenly. In 1825, for example, he knew Scrope only slightly andreferred to his Considerations on Volcanos merely as \"a very creditablework.\" ^ He did not then see in it implications which would upset dilu-vialist assumptions. \"I was,\" he later wrote, \"taught by Buckland thecatastrophical or paroxysmal theory,\" and not until 1827 does his pub-lished correspondence begin to mention the existence of a definite \"liberal\"camp in geology.^ By the end of that year, however, he had delivered themanuscript of his first volume to the printer, who must have become alittle annoyed with uniformitarianism, because, what with several morecontinental tours and continual changes in detail, Lyell did not get thebook through the press until January 1830, though he later declared themain points of his theory to have been fixed before he wrote his firstdraft.^^ For so single-minded a work, the Principles came out in remark-ably haphazard fashion. Originally Lyell had planned two volumes. Thecounterattacks of the opposing school compelled him to modify his tactics,and he altered his plan so that each volume would not only cover itsphase of physical history interpreted in terms of the present but wouldalso meet the objections raised by the preceding installment. In the end,volume II appeared in January 1832, a second and revised edition ofvolume I in June 1832, and volume III in April 1833. The time had come, announced Lyell, for a proper science of the earthand of its inhabitants, and he proposed to set it forth. It was now for thefirst time possible to do so. The suspension, since around 1810, of allattempts to form cosmogonies had been a salutary reaction against theAexcesses of Neptunism. host of industrious toilers had accumulated agreat new body of data, and, by avoiding generalizations, \"they in a fewyears disarmed all prejudice, and rescued the science from the imputationof being a dangerous, or at best but a visionary pursuit.\" ^^ They also pro-

22 CHARLES COULSTON GILLISPIEvided Lyell with the raw materials for a book. What is the good, asked Lyell, of describing results, if their causes be necessarily a matter of inde- terminate speculation? There had, of course, been considerable progress. But instead of hearing that fossils are sports of nature, or rock strata the result of aqueous precipitation, we now hear of sudden and violent revo- lutions of the globe, called in by scientists more anxious to cut the Gordian knot of knowledge than to unravel it.^^ Whoever would unravel the tangled skein of phenomena which the face of the earth presents to view and discover a single, intelligible thread therein must accept this doctrine: that all former changes of the organic and inorganic creation are referrable toone uninterrupted succession of physical events, governed by the laws now inoperation. . . . The principles of science must always remain unsettled so longas no fixed opinions are entertained on this fundamental question.^^Hutton, indeed, had approximated the uniformitarian position, and asa result the study of the earth as a science dates from his work. Butalthough Hutton had properly remarked that science could study onlycauses of the same kind as those observable in the dynamics of presentchanges, he had fallaciously allowed for a difference in intensity of opera-tion because his theory of thermal uplift postulated alternating periodsof disturbance and repose.^^ Later generations had unfortunately takenadvantage of this loophole to neglect the Huttonian attitude, and to bringin changes so catastrophic as to differ in kind. Lyell's strong insistence upon the distinctiveness of his own approachlaid him open to charges of plagiarism levied by opponents who protestedthat, however infidel his system, it did not possess the merit of an originalheresy. Even a reviewer who was sympathetic towards Lyell's general atti-tude made this point,^^ and indeed much of uniformitarianism was im-plicit in Hutton. For Lyell, too, science could not concern itself withorigins of the universe, \"a metaphysical question, worthy a theologian.\" ^°He built his synthesis on the methodological limitation that the pastcould be studied only by analogy to what natural agencies can accomplishin the present. Such theoretical originality as uniformitarianism possessedlay in its pushing the analogy to an identity, in its rigorous, undeviatinginsistence that existing forces, given time enough, account for the observ-able state of man's habitat. The three skillful and lucid volumes of the Principles of Geology weredevoted simply to marshaling the evidence in support of this simple thesis,and since the contention required that there be no exceptions, the resultcame very close to being a Summa Geologica. But first, it was necessaryto point out why geologists had been so long in finding out what theirsubject was, and why their work had so often been ill received. The in-herent difficulties of the science, Lyell thought, had rendered it pecu-

THE UNIFORMITY OF NATURE 23liarly susceptible to the interpretations of ancient miraclemongers andtheir modern successors. The most ubiquitous stumbhng blocks werepopular preconceptions in regard to the extent of past time. If one hadto produce our world out of a hat only six thousand years old, one obvi-ously must call upon extraordinary deviations from the normal course ofevents, even though one might admit that nature now proceeds accordingto uniform laws. Aside from the authority of the Mosaic chronology, fur-ther obstacles arose from our unfortunate position as land animals, asituation eminently unfavorable for geological observation. Human beingsinhabit only about a quarter of the globe, and that quarter the one whichWeis the theater of decay. know of, but cannot observe, the progress ofAnew formations under the land and beneath the seas. race of fish withhuman intellects, thought Lyell, would have built a proper, sound naturalhistory much sooner than we have done.^^Having stated his thesis and, as he thought, exposed the popular andtheological prejudices against it, Lyell set himself and his readers to in-quiring how the vicissitudes which the earth's surface obviously had ex-perienced \"can be reconciled with the existing order of nature,\" ^^ He didnot, of course, deny the reality of change, but he insisted that all changehad been uniform, proceeding in cycles in time rather like the orbits inspace through which the planets swing. The climatic conditions of anygiven spot, for example, had varied with the continual shifting in therelative proportions of land and sea in that particular portion of the globe.Volume I devoted itself to describing the geological dynamics which occa-sioned such changes. Familiar examples of the mode in which the variousagents behave were pointed out—the action of the atmosphere and ofliving organisms, of volcanoes and earthquakes, and above all of water.After each contemporary or historical illustration the point was made thatthe cumulative effects of such common forces had produced the phe-nomena which Cuvier and Buckland referred to cataclysms of an essen-tially miraculous character. In similar fashion, the second volume dealtwith changes now in progress in the animate creation and showed them tobe the only kind ever to have occurred. The last volume, in spite of thenecessity for a number of digressions occasioned by objections to the firsttwo, was largely descriptive. It incorporated the latest developments inchronological stratigraphy, paleontology, and physical geography, and itincluded Lyell's most important constructive contribution to the sciencein his identification and separation of the Pliocene, Miocene, and Eoceneepochs of the tertiary period. ^^ Lyell professed to have derived his theory entirely from appearances,Aand no doubt he thought he had done just that. crudely additive induc-tive approach still enjoyed an almost exclusive methodological vogue in1830, and though the chance that a hypothesis may be deduced from abrilhant intuitive flash would damn it out of hand no longer, such an

24 CHARLES COULSTON GILLISPIEadmission would have killed it then, even for its originator.^o Actually,however, after abstracting the central idea implied by Hutton and Play-fair, Lyell simply universalized the principle of uniformity and then ar-ranged the facts in accordance with it. The process necessarily involvedsome incidental special pleading. Lyell was, of course, perfectly aware that the flood was his chief enemy,because to many minds the diluvial theory alone seemed capable of afford-ing an explanation of natural phenomena in accordance with scripturalhistory.2^ And being chary of disturbing religious convictions unduly, heimpugned the deluge explicitly in only one passage, and that one ratherin the nature of a digression. Generally, he preferred the method of drain-ing the flood of its influence incidentally to the development of his largerinterpretation. And where he does allude to the flood, what he objects tois its universality and its geological efficacy, not its existence. It had long been a question among the learned, even before the commence-ment of geological researches, whether the deluge of the Scriptures was uni-versal in reference to the whole surface of the globe, or only so with respectto that portion of it which was then inhabited by man. If the latter interpreta-tion be admissible, the reader will have seen, in former parts of this work, thatthere are two classes of phenomena in the configuration of the earth's surface,which might enable us to account for such an event. First, extensive lakeselevated above the level of the ocean; secondly, large tracts of dry land de-pressed below that level. ^^That is to say, a lake like Titicaca, far above sea level, might burst itsbanks and flood the neighboring lowlands, or a very depressed land area,like the Valley Jordan, might be inundated by a break in the barriers sur-rounding it. Such, Lyell implies, was the Mosaic deluge. He admitted itto be undeniable, however, that recent naturalists had followed Bucklandalmost to a man in picturing the flood as violent, universal, and a pri-mary geological agency. But we agree with Dr. Fleming, that in the narrative of Moses, there are noterms employed that indicate the impetuous rushing of the waters, either asthey rose or when they retreated, upon the restraining of the rain and the pass-ing of a wind over the earth. On the contrary, the olive-branch, brought backby the dove, seems as clear an indication to us that the vegetation was notdestroyed, as it was then to Noah that the dry land was about to appear.^^ It is somewhat surprising to find the evidence of the olive branch inLyell as well as in Kirwan, though one suspects that when Lyell intro-duced it, he had his tongue in his cheek. Lyell, however, never questionedthe accuracy of the Pentateuch in its own realm, which was historical andreligious. He did not even intend to discredit it as the description of anactual geological event, provided the event was interpreted simply as anincident in the regular course of nature, but he hoped the issue would

THE UNIFORMITY OF NATURE 25\"Wenot be pursued. have been led with great reluctance into this digres-sion, in the hope of relieving the minds of some of our readers fromgroundless apprehension respecting the bearing of many of the viewsadvocated in this work.\" ^^The subject of volume II, however, was not a digression. The whole ofit was devoted to a discussion of the animate creation and the vicissitudeswhich species undergo. \"To Geology . . . these subjects do strictly apper-tain\"; 2^ and the basic question is, \"First, whether species have a real andpermanent existence in nature; or whether they are capable, as somenaturalists pretend, of being indefinitely modified in the course of a longseries of generations?\" ^^ Lyell offered his readers an admirably clear anddispassionate exposition of Lamarck's theories. He was perfectly fair andperfectly sure that they were wrong, and his refutation of the doctrine ofprogressive development of life took the form of an equally clear precisof Cuvier's arguments.^^ Each species \"was endowed, at the time of its creation, with the attri-butes and organization by which it is now distinguished.\" ^^ Only limitedvariations within a type have ever occurred. Each species, itself immutable,probably takes its origin from a single pair, such pairs having \"been createdin succession at such times and in such places as to enable them to mul-tiply and endure for an appointed period, and occupy an appointed spaceon the globe.\" ^^ Linnaeus had been mistaken in supposing that one cor-ner of the globe had once been set aside as a divine incubator; instead,life had obviously originated in a number of \"foci of creation.\" Races ofanimals have, of course, become extinct and the globe repopulated bynew creations from time to time, although it is somewhat unsetthng \"thatso astonishing a phenomenon can escape the observation of naturalists.\" ^^As to the most important point, Lyell agreed with Bishop Berkeley, who\"a century ago . . . inferred, on grounds which may be termed strictlygeological, the recent date of the creation of man.\" ^^ But neither theappearance of man nor the disappearance of other species is to be con-sidered a break in the uniformity of natural variation. We cannot conclude this division of our subject without observing, thatalthough we have as yet considered one class only of the causes (the organic)whereby species may become exterminated, yet the continued action of thesealone, throughout myriads of future ages, must work an entire change in thestate of the organic creation. . . . The mind is prepared by the contemplationof such future revolutions to look for the signs of others, of an analogousnature, in the monuments of the past. Instead of being astonished at the proofsthere manifested of endless mutations in the animate world, they will appearto one who has thought profoundly on the fluctuations now in progress, toafford evidence in favor of the uniformity of the system, unless, indeed, weare precluded from speaking of uniformity when we characterize a principle ofendless variation.^^

26 CHARLES COULSTON GILLISPIE It has often been suggested that Lyell was on the verge of hitting uponan evolutionary theory of organic nature, and it is true that, with benefitof hindsight, uniformitarianism in geology seems almost to cry out forevolutionism in biology. In this general and important sense, Lyell un-doubtedly prepared the way for Darwin. Lyell did not have the benefit ofhindsight in the 1830's, however, and at the time he was forced to rejectthe idea that organic life had developed through modification of species,because the conception of a progressive approach to the present order ofthings, which Lyell referred to as \"the ancient doctrine,\" ^^ was relied onvery heavily by his opponents. This is not surprising when it is recalledthat \"progressive\" is not necessarily the same as \"evolutionary\"—it alldepends on how the progress comes about, whether by providential inter-ventions or by natural laws. Lyell did not perceive the possibility of amalgamating progress withuniformity by substituting transmutation of species for successive crea-tions. Instead, he tended to deny the progressive character of earth his-tory. The more subtle of the Mosaicists, on the other hand, urged thatextraneous fossils and extinct vertebrates exhibit a continued developmentof organic life from the simplest to the most complicated forms. Sir Hum-phry Davy, and with him nearly everyone else, thought that \"there seems,as it were, a gradual approach to the present system of things, and a suc-cession of destruction and creation preparatory to the existence of man.\" ^^Lyell thought the recent creation of man to be indisputable, but the re-mainder of the proposition, \"though very generally received, has nofoundation in fact.\" ^^ The argument was a little weak here, and Lyellseems not to have been entirely comfortable with it. His theory had toaccount for the absence of the remains of mammalian quadrupeds in themore ancient rock formations. Lyell's explanation was not that specieslike lions and elephants had appeared only in recent ages, but that inthe successive metamorphoses of older rocks, all traces of these larger,softer, and less durable terrestrial forms had been destroyed.^^ This fact,since we know how present causes destrov such relics, offers further proofof uniformity in the past population of the globe. One might well wonder why the absence of relics should be proof bothof the uniform antiquity of other species and of the recent date of man'screation, but Lyell never noticed the inconsistency. His purpose was todemonstrate that our creation had not been an event so exceptional asto constitute a break in the continuity of nature: The introduction at a certain period of our race upon the earth, raises nopresumptions whatever that each former exertion of creative power was char-acterized by the successive development of irrational animals of higher orders.^^Comparison between men and animals strains the bounds of valid analogy.Though it was a new departure for the creative power to link \"moral and

THE UNIFORMITY OF NATURE 27intellectual faculties capable of indefinite improvement, with the animalnature,\" that it did so does not justify the assumption of any correspond-ing steps in a hypothetical progression of purely physical forms.^^ It might be thought that uniformitarians would be more uncompro-mising opponents of Darwin than catastrophists, but it did not fall outso in the event. Attitudes are more lasting than theories, and in any caseLyell was not likely to achieve a prestige as imposing as that of Moses.In later times, when Lyell ranged himself by Darwin's side, his earlierwritings did indeed supply their opponents with a limited store of obso-lete ammunition. But if anything is more damaging than a Pyrrhic victory,it must be a Pyrrhic defeat; and though providentiahst critics of uniformi-tarianism did not prevail in the 1830's, they seized avidly on its incon-sistencies and gave a suggestive airing to notions of progressive develop-ment. It would not be too difficult to substitute natural selection forprovidential cataclysms and divine creations.For all that his attack upon scriptural geology was oblique, Lyell wasthoroughly aware that his chief enemies would be \"the ancient and mod-ern physico-theologians.\" ^^ The real purpose of his book was \"to sink theHediluvialists, and in short, all the theological sophists.\" '^^ had beforehim, however, a horrid example of what might come from such an effort,and he was most anxious not to reawaken an uproar similar to the onewhich had greeted Hutton's theories.The mind of the English public was at that time in a state of feverish ex-Acitement. class of writers in France had been labouring industriously formany years, to diminish the influence of the clergy, by sapping the foundationsof the Christian faith, and their success, and the consequences of the Revolu-tion, had alarmed the most resolute minds.*^Lyell, like most British scientists, never thought of himself as having any-thing in common with the tradition of rationalist skepticism. Quite thereverse, for Voltaire, who in Lyell's view had misinterpreted physics inorder to ridicule the Scriptures, had also poked fun at the cultivators ofgeology, \"regarding the science as one which had been successfully en-listed by theologians as an ally in their cause.\" ^^ No good would comeof this sort of thing, either for science or religion, and Lyell desired eachto return to its proper sphere, before they had hopelessly compromisedone another once again. If ever Mosaic natural history could be set down without giving of-fense, thought Lyell, it would be in a historical sketch,^^ and he verymuch wanted to avoid giving offense. His letters began to express worryabout the reception his volumes would meet with before he started writ-ing them. He may, he fears, have to sustain the episcopal wrath of thewhole bench of bishops, newly roused to ire by the Reverend Mr. Mil-

28 CHARLES COULSTON GILLISPIEman's History of the Jews. On the other hand, there is a hopeful chancethat the furor over unfrocking Milman may create a diversion in hisfavor.^^ Tact, he urges his friends Mantell and Scrope, tact. Let themnot run \"unnecessarily counter to the feelings and prejudices of the age.\" ^^ Lyell attached great importance to preparing public opinion to accepthis views. The traditional orthodoxy of the Quarterly Review made it thekey organ in his campaign, and Lyell discovered in advance that ScropeAwould be his reviewer therein. series of letters, written before the PrirL-ciples appeared, briefed Scrope on what to say. \"If Murray has. to pushmy volumes, and you wield the geology of the Quarterly Review, we shallbe able in a short time to work an entire change in public opinion.\" ^®The resultant article was, not unnaturally, eminently satisfactory; it turnedone of the enemy's main batteries against him.'*'^ Lyell was not an undulysensitive person, but he had a bad case of literary apprehensiveness as hesaw his pages through the press. His concern cannot be laid to his tem-perament; it can only have arisen from his appreciation that, howevercarefully his argument sought to ignore the issue, its imphcations randirectly counter to a deep current of accepted opinion.^^ The question naturally arises, what of Lyell as a scientific thinker?It is, indeed, obvious that he did protest too much. All his opponentsimmediately pointed out that the \"attempt to explain the former changesof the earth's surface by reference to causes now in operation\" was in-trinsically no more objective than the effort to explain them by refer-ence to a comet, a flood, or whatever catastrophes might be indicated.Lyell gave himself away, they said, by his frequent use of the word\"reconcile\" and achieved only a patent over-reconciliation.^^NoGeologically, of course, Lyell's critics were right. one now holdssuch extreme views upon the uniform course of nature. As early as 1840,although the immediate issue as to the universal efEcacy of contemporarycauses was not settled, neither did the problem taken simply as a geo-logical one provoke much discussion. Sir Roderick Murchison's The Si-lurian System, which was published in 1839, and which after Lyell's Prin-ciples was the next major contribution to the science to appear in Eng-land, seldom even alludes to the uniformitarian-catastrophist debate or toany theoretical controversies.^^ But the question had become very muchmore than a geological one, and the root of Lyell's ideas lay outside thebounds of that science, wide though they then were. By 1830, he wrote,in all branches of natural knowledge, and even in enigmas of the moralworld, the advancement of learning was presenting more and more ofthe phenomena which an ignorant past had attributed to miracles, todemons, to divine interventions, or to other extraordinary agencies asmerely manifestations of larger laws, more perfectly understood.

THE UNIFORMITY OF NATURE 29 The philosopher at last becomes convinced of the undeviating uniformity of secondary causes, and guided by his faith in this principle, he determines the probability of accounts transmitted to him of former occurrences.^^ Uniformitarian presuppositions, then, were simply those of optimisticmaterialism. It would take time, and Darwin, to demonstrate how hope-lessly Buckland's school was out of key with the times—witness Lyell'sapprehensiveness and the Principles inclusion of certain Mosaic details.But however pervasive the hold of catastrophism in 1830, materialisticscience had almost cut the ground from under materialistic theology,even then. Gratuitous LAell's assumption may have been, but it openedthe way for scientific progress, while Buckland's blocked the very pathhe sought to tread. After 1859, the surviving catastrophists, although theyhad tO)'ed with ideas of organic progression in the 1830's, were to befound solidly behind Wilberforce; while the uniformitarians who werestill alive supported Darwin and Huxley, despite volume II of thePrinciples. 3 The uniformitarian thesis was launched with considerable eclat, and itbecame immediately the object of widespread attention.^^ j^- (jf^j ^ot,however, win the universal and enthusiastic assent which had hailed Buck-land's magnum opus seven years earlier. Lyell's arrangement of the evi-dence, as it flowed from the press, wore the opposition down instead ofoverwhelming it, and chipped away the catastrophic positions in some-what the same fashion as that in which his rivers produced a gradual, ifmuch less rapid, degradation of land surfaces. Even his opponents ex-tended the work their hearty approval insofar as its purely descriptivefeatures were felt to be the most skillful and interesting presentation ofthe subject ever set before the pubhc. Before attacking its conclusions,most of them injudiciously and somewhat ostentatiously welcomed theopportunity to discuss theoretical first principles.^^ Adam Sedgwick, before attacking all of Lyell's main points, felt con-strained to express his appreciation of \"the instruction I received fromevery chapter of his work, and of the delight with which I rose from theperusal of the whole.\" ^* The effort, too, to disarm religious oppositionhad been fairly successful, at least to the extent that no reputable scientistexploited the whirlwind of theological outrage which was blowing up ona cruder level of criticism. Lyell even attributed his election to a chairin King's College, London, to Conybeare's intervention with the bishopswho controlled the appointment and who were told that Lyell's doctrineswere \"startling enough, but not . . . come by in otherwise than a straight-forward manner\" or \"from any hostile feeling towards revelation.\" ^^ Thebishops were uneasy, but they managed to master their qualms.

30 CHARLES COULSTON GILLISPIE Publishers hastened to take advantage of the renewed interest in naturalhistory aroused by Lyell, and a host of new titles, or of new editions ofold titles, were rapidly bought up as soon as they appeared on the bookstands. Macculloch, Mantell, Conybeare and Philhps, Jameson, Bake-well, and Brande got out revised versions of their commentaries. Gran-ville Penn, Andrew Ure, Bishop Copleston, and John Faber, among others,appeared with the latest refinements of scriptural geology. Lyell's volumes,too, went through a number of editions. As the debate developed, the most prolific of Lyell's supporters wasGideon Mantell, a competent geologist who was not of an original turnof mind and whose work, therefore, was abreast of his time but neverahead of it. His books are useful as examples of the adoption and popu-larization of Lyell's ideas by the uniformitarian school. Mantell's discov-ery of the iguanodon was his major claim to fame. He was a surgeon byprofession, a highly successful popular lecturer—receiving as much astwenty-five pounds for lectures at charity benefits ^^—and something of asocial climber. He evidently hoped to emulate Sir Humphry Davy inrealizing his social ambitions by achieving scientific eminence, and likeDavy he was also sincerely interested in research for its own sake. Scienceeven cost him his wife, who left him when his collection of specimensand fossils grew so large and so popular that it crowded the family outof their home, which had become virtually a public museum. Mantell got out a number of geological works written for the generalpublic.^^ The Geology of the South-East of England, the expansion ofan earlier work,^^ appeared in 1833. At this time Mantell's interpretationsshowed little evidence of uniformitarian influence. In his general sketchof the science he referred in conventional fashion to causes still in opera-tion which date \"from the period when our continents and islands as-sumed their present form,\" and he distinguished between the alluvial anddiluvial deposits overlying the tertiary formations— though he refused tocommit himself as to whether the Biblical flood was responsible fordiluvium.^^ In the Wonders of Geology, however, first published in 1838,Mantell gave a precis of Lyell's description of contemporary causes andasserted them to have been sufficient for all time. Formations were nowclassified as metamorphic, secondary, and tertiary, and the tertiary periodwas broken down into Eocene, Miocene, and Pliocene. Mantell still usedthe word \"alluvial\" for loose, water-borne accumulations, but \"diluvial\"no longer appears. There are a number of passages in the Wonders of Geology which il-lustrate how uniformitarianism seems (to the modern reader) almost tohave demanded an evolutionary explanation of organic phenomena. If,for example, \"naturalistic development\" were substituted for \"the Crea-tor\" in the following sentences, they would read like a vague anticipationof Darwin:

THE UNIFORMITY OF NATURE 31 The fluctuating state of the earth's surface, with which our previous inquirieshave made us famihar, will have prepared us for the disappearance of some—species of animals; and here another law of the Creator is manifest. Certainraces of living beings, suitable to peculiar conditions of the earth, appear tohave been created; and when those states became no longer favourable for thecontinuance of such types of organization, according to the natural laws bywhioh the conditions of their existence were determined, the races disappeared,and were probably succeeded by new forms.^\"For the uniformitarian school in the 1830's, however, the activities of theCreator still supplied a satisfactory hypothesis covering the evidence laterexplained by evolutionary theory. Mantell even refers to human skeletonswhich had been discovered in Guadeloupe encased in limestone and tohuman footprints found in a block of the same material in Missouri, buthe regards this as proof that the formations were recent and not that manis ancient. The point is simply stated, not argued.®^The Wonders of Geology was a uniformitarian text for laymen, andMantell attached considerable importance to quieting the uneasiness ofpeople who might have been misled by the hostility of uninformed theo-Whenlogians. science and religion are properly understood and theirspheres kept distinct, there is, he assured his readers, no conflict betweenthem. There were very few scientists in Mantell's generation who did notmake this point at some time or other, and like the great majority ofthem Mantell did not perceive that his position logically required therejection of the whole framework of conventional natural theology. Ratherthan attempt any original contribution to the well-worked subject himself,he preferred to disarm suspicion by stating the views of the \"eminentphilosophers and divines\" whose central opinions were so widely acceptedthat they had rescued geology from the \"absurd and unfounded\" chargeof being inimical to Christian piety.^^ The philosophers and divines herelied on were, most of them, catastrophists like Whewell, Buckland, andSedgwick. While rejecting their particular theories regarding the courseof nature, Mantell did not hesitate to adopt their fundamental interpreta-tion of the meaning of nature. The new page in the volume of natural religion, which Geology has supplied,has been so fully illustrated by Dr. Buckland, in his celebrated Essay,^^ thatI need not dwell at length on the evident and beautiful adaptation of the organ-ization of numberless living forms, through the lapse of indefinite periods oftime, to every physical condition of the earth, and by which its surface wasultimately fitted for the abode of the human race.It is enough to point out that \"we must believe, that every physicalphenomenon which has taken place, from first to last, has emanated fromthe will of the Deity.\" ^^ Although Mantell's reader is repeatedly toldthat geology had nothing to do with the Bible, this does not seem to

32 CHARLES COULSTON GILLISPIEhave meant that science had no religious imphcations. All it meant wasthat Scripture had no scientific implications. Mantell adopted uniformitarian geological theories somewhat uncriti-cally, but he never rose above the more general presuppositions of theperiod. Henry de la Beche, on the other hand, in spite of many reserva-tions about the specific thesis of Principles of Geology, came much closerto accepting Lyell's central attitude towards science. De la Beche was thefirst director of the Geological Survey, founded in 1835, and like Mantellhe wrote several popular texts and elementary manuals designed to assistthe amateur observer towards a constructive enjoyment of his hobby,^^Though not a uniformitarian, neither had De la Beche ever been a scrip-tural catastrophist. He represents, in fact, the tendency to ignore allquestions of the sort—a tendency not yet very marked. For De la Beche,\"The difference in the two theories is in reality not very great; the ques-tion being merely one of intensity of forces, so that, probably, by unitingthe two, we should approximate nearer to the truth.\" ^^ He did, it istrue, assume that there must have been successive creations of species, butin this he was simply expressing the current hypothesis. He did not relateit to the Biblical account.^^ De la Beche's own interpretations of thegeological evidence were closer to the catastrophist than to the uniformi-tarian pattern, but entirely without Mosaic allusions or overtones, and asa result his writings were both temperate and, compared to the rest of thediscussion, rather dry.®^ The orthodox opposition was more excited and, after an initial periodof disorganization, took up its positions on lines of argument so welldefined as to indicate careful staff planning. The catastrophist high com-mand centered in the universities. Buckland and Sedgwick still held thechairs of geology at Oxford and Cambridge. Daubeny was professor ofchemistry at Oxford, Conybeare a fellow of New College, and Whewellsenior tutor and later master of Trinity College, Cambridge. Nearly everymeeting of the Geological Society appears to have resolved itself into adebate between Lyell's supporters and this \"Oxford School of Geology.\" ^^In general scientific circles, the Oxford school seems to have been thoughtthe more reputable and the safer of the contending groups. Buckland waselected second president of the British Association for the Advancementof Science in 1832, and Conybeare the chairman of its geological section. One thing the Principles of Geology unquestionably accomplished. Thebook administered the coup de grace to the deluge. Few denied that Moseshad indeed described an impressive flood, but as a primary, universalgeological agency, it was abandoned. It is, of course, interesting that Lyellfelt required to find a humble niche for it in his picture of a uniformpast, and that he specifically comforted Bishop Copleston of Llandaff byassuring him that there was \"no objection to his drowning as many peo-ple as he pleased on such parts as can be shown to have been inhabited

THE UNIFORMITY OF NATURE 33in the days of Noah.\" ^'^ But the speed with which the ecumenical floodevaporated is starthng. As late as 1829 the period at which a flood operatedwas still regarded as central to chronological classification. Daubeny, it istrue, did attempt to preserve some scope for violent aqueous action, butonly in the formation of volcanoes and of valleys and not as a unique,world-wide event. He made this point in the course of a general argumentto the effect that catastrophes greater than any we now see could beproduced by present causes acting more intensely, and that he and Lyell,therefore, differed only on a question of degree. Although he thought itpossible that \"a doctrine in science may be true, although involving ques-tions that cannot be reconciled, at the time, to the statements of Scrip-ture,\" he also felt that his position, as opposed to Lyell's \"has the furtheradvantage of rendering the accounts of such catastrophes, which arehanded down to us on the authority both of history and tradition, con-sistent with probability, instead of opposed to it . . . and thus, if notdirectly confirming the Mosaic history on this particular point, removingat least those obstacles to its reception that might exist, if we consideredthe event related as out of the course of nature.\" Scripture was not asource for science, of course. In the case of conflicting theories, however.Scripture may, Daubeny held, appropriately be used to tip the balance ofprobability one way or the other.'^^ The faithful were unable to take much satisfaction in so limited acatastrophe as Lyell's deluge allowed them, and most of them either lostinterest in it or hastened to abandon it. Whewell, who, according toLyell, \"has more influence than any individual, unless it be Sedgwick,\" '^^now contemptuously dismissed \"those who have framed their geology byinterpretations of Scripture.\" He still, however, allowed a limited validityto thosegeological speculations in which the Mosaical account of the deluge has beenreferred to; for whatever errors may have been committed on that subject, itwould be as absurd to disregard the most ancient historical record, in attempt-ing to trace back the history of the earth, as it would be gratuitously to rejectany other source of information.^^But Whewell no longer felt inclined to introduce this particular evidenceinto the argument. Conybeare backtracked even more hastily, though less unreservedly.He had been so impressed with the Principles, and so disturbed by theirimplications, that he prevailed upon the editor of the Philosophical Maga-zine to run a series of pieces in which he took issue with all of Lyell'sinterpretations and with many of his specific illustrations.^^ These ar-ticles furnish the most complete statement of the catastrophist counter-offensive. Conybeare professed to adhere to the diluvial theory, but \"onlyin a general and philosophical sense. Theologically, I am well contented

34 CHARLES COULSTON GILLISPIEto let the Scriptural narrative rest on its appropriate moral evidence, andshould only fear to weaken that evidence by mingling it with my owncrude scientific speculations.\" This was a new fear with Conybeare, andhe seems to have mastered it fairly rapidly, because his next sentence il-lustrates nicely the distressing necessity for reconciliation which arose fromhis religious beliefs— or were they doubts? I hold indeed, that Science, by exhibiting to us the independent evidenceof analogous convulsions, may well be cited, as removing from that narrativeall objections arising from alleged antecedent improbability: but whether thediluvial traces we still observe geologically, be the vestiges of the Mosaic deluge,or whether that convulsion was too transient, etc., to leave such traces, isquite another question.''^ Upon the deluge itself, Adam Sedgwick's apostasy was even more un-compromising and his recantation as president of the Geological Societyalmost ostentatiously manly:Having been myself a believer, and, to the best of my power, a propagatorof what I now regard as a philosophic heresy ... I think it right, as one ofmy mylast acts before I quit this Chair, thus publicly to read recantation.We ought, indeed, to have paused before we first adopted the diluviantheory, and referred all our old superficial gravel to the action of the MosaicFlood. For of man, and the works of his hands, we have not yet found asingle trace among the remnants of a former world entombed in thesedeposits.^^The imphcation is significant. If relics of humanity had been foundin the debris of a destroyed world, then we would have evidence that thedestruction had been wrought by the Mosaic flood which, as we know,drowned a great many human beings. Sedgwick never abandoned the ideaof sudden and universal geological catastrophes even though the Biblicaldeluge could no longer be one of them. Buckland, at this time, was preparing to meet the uniformitarian chal-lenge in his contribution to the Bridgewater Treatises. Much was hopedfor from him by the trustees and devotees of that once popular series, andin the meantime rumors of the course his thoughts were taking wereeagerly seized upon in scientific circles. Even his opponents never doubtedBuckland's original sincerity. \"Although I am convinced,\" wrote Lyell, \"hedoes not beheve his own theory now, to its full extent, he beheved itwhen he started it.\" ^^ And later, Lyell hears that Buckland has changedhis plan again, and that his \"mode of reconciling geology and Genesis inhis B. Treatise has been approved of by the Oxford Professors of Divinityand Hebrew!\" ^^ As it turned out, Buckland never mentioned the delugein his treatise. Sedgwick, indeed, made an abortive effort to account forit as a product of the paroxysmal earthquakes postulated in Beaumont's

THE UNIFORMITY OF NATURE 35mountain-uplift theories.'^^ But uniformitarians had no difficulty in block-ing this new tack of the diluvialists.^\" The deluge was finished. All this meant, however, was that catastrophism had been deprived ofits most popular catastrophe. Upon the larger question of the relationsbetween scientific theory, natural causation, and religious truth, the atti-tudes which had given rise to diluvialism remained stubbornly unaffectedby the demise of that specific interpretation. Sedgwick, for example,worked up to his criticism of Lyell by way of some general remarks on thelaws of nature and the comprehension of them. He was then presidentof the Geological Society. His attack, wrote Lyell, was the \"severest,\" andthe one against which he must put forth all his energies in the secondvolume of the Principles.^^ \"1 believe,\" declared Professor Sedgwick, \"that... all the primary modes of material action, are as immutable as theattributes of that Being from whose will they derive their only energy.\"The basic laws of nature, the law of gravitation, for instance, or of atomicaffinity, are few and simple and not yet all discovered. Uniformitarianismconfounded imperfectly comprehended appearances with some such basiclaw. It was a Ptolemaic view of earth history. \"It assumes, that in thelaboratory of nature, no elements have ever been brought together whichwe ourselves have not seen combined; that no forces have been developedby their combination, of which we have not witnessed the effects.\" ^^It circumscribes, in other words, God's operations by our ignorance ofthem. At this level, Sedgwick was a penetrating critic. As an irreducible minimum, catastrophists required that theories of nat-ural causation admit of direct providential application. In this demand,never explicitly formulated, lay the root of all the troubles, and to satisfyit the Oxford school followed Sedgwick onto very treacherous ground.Conybeare had calmed down a little by 1832, when, as first president ofthe new British Association's geological section, he delivered his annualcharge No real philosopher, I conceive, ever doubted that the physical causes whichhave produced the geological phenomena were the same in kind, however theymay have been modified as to the degree and intensity of their action, by thevarying conditions under which they may have operated at different periods.It was to these varying conditions that the terms, a different order of things,and the like, were, I conceive, always intended to have been applied; thoughthese terms may undoubtedly have been by some writers incautiously used.®^Conybeare continued to feel fundamental reservations about the identityof causes in degree and in intensity, while admitting that the SupremeLawgiver always moved in similar ways His wonders to perform. Thesereservations ultimately prevailed, to be sure, though scarcely in the wayConybeare presented them. Still, he painted an impressive and persuasive picture of a progressing global surface, of a progressive set of creations,

36 CHARLES COULSTON GILLISPIEeach more complicated than the last. Sciences even had developed in alogically necessary order of succession, from astronomy to geology. Grad-ually the globe had changed from a fluid spheroidal mass to a solid crust,itself still cooling in paroxysms less and less intense. This globe bore adifferent aspect in every age. As natural forces degenerated from age toage, the planet was inhabited by successively more advanced animalcreations. Sedgwick too had discovered in his meditations upon the organic crea-tion the most insuperable objections to uniformitarianism. And I ask you, have we not in these things some indications of change andof an adjusting power altogether different from what we commonly understandby the laws of nature? Shall we say with the naturalists of a former century,that they are but the sports of nature? Or shall we adopt the doctrine ofspontaneous generation and transmutation of species, with all their train ofmonstrous consequences? **Lyell, to be sure, devotes a chapter to combating successfully the latterspeculation. \"A doctrine may however be abused,\" thought Sedgwick,\"and yet contain many of the elements of truth.\" I think that in the repeated and almost entire changes of organic types in—the successive formations of the earth in the absence of mammalia in theolder, and their very rare appearance (and then in forms entirely unknown to—us) in the newer secondary groups in the diffusion of warm-blooded quad-—rupeds (frequently of unknown genera) through the older tertiary systems intheir great abundance (and frequency of known genera) in the upper portions—of the same series and, lastly, in the recent appearance of man on the surface—of the earth (now universally admitted) in one word, from all these facts com-—bined, we have a series of proofs the most emphatic and convincing, thatthe existing order of nature is not the last of an uninterrupted succession ofmere physical events derived from laws now in daily operation: but on thecontrary, that the approach to the present system of things has been gradual,and that there has been a progressive development of organic structure sub-servient to the purposes of life.*^ This weighty sentence took Sedgwick onto very thin ice indeed, butWilliam Whewell in the British Critic skated even closer towards the finalcatastrophe of the cataclysmic creed: It is clear . . . that to give even a theoretical consistency to his system, itwill be requisite that Mr. Lyell should supply us with some mode by which wemay pass from a world filled with one kind of animal forms, to another, inwhich they are equally abundant, without perhaps one species in common. Hemust find some means of conducting us from the plesiosaurs and pterodactylsof the age of the lias, to the creatures which mark the oolites or the iron-sand.He must show us how we may proceed from these, to the forms of those later

THE UNIFORMITY OF NATURE 37times which geologists love to call by the sounding names of the paleotherianand mastodontean periods. To frame even a hypothesis which will, with anyplausibility, supply this defect in his speculations, is a harder task than thatWewhich Mr. Lyell has now executed. conceive it undeniable (and Mr. Lyellwould probably agree with us,) that we see in the transition from an earthpeopled by one set of animals, to the same earth swarming with entirely newforms of organic life, a distinct manifestation of creative power, transcendingthe known laws of nature: and, it appears to us, that geology has thus lighteda new lamp along the path of natural theology.^® So there the question stood. It could not have been more clearly stated. Deluc, Kirwan, Conybeare, Sedgwick, and Buckland might almost be de- scribed as having written the last chapter in a historical interpretation to which Orosius and Gregory of Tours had contributed the early volumes. Their approach to natural history in the half-century of their scientific leadership disguised its lust for the catastrophic and the miraculous more successfully, perhaps, than the Seven Books Against the Pagans, but thecompulsion to exhibit examples of divine intervention was strong. Neptunists and catastrophists set themselves a task which ultimatelyproved self-contradictory. They accorded complete philosophic validity towhatever results Baconian induction might bring them; and they also re-quired these results to display the structure and development of the ma-terial world as the history of an intending Providence with a moral pur-pose, as physical evidence not only of God's power but of His will andHis immediacy. However firmly they might insist that Genesis was notdesigned to teach the truths of science, or the Geological Society to teachthe truths of morality, still truth, as Sedgwick felt, could not be incon-sistent with itself. The central thread of interpretation became finer andfiner. One by one its strands were broken and the weight of demonstra-tion put upon those remaining—the six days of creation, the six-thousand-year span of earth history, the birth of our present globe in a primevaldiluvium, the antiquity and original parentage of species, the dynamicalefficacy of divinely ordained cataclysms, the flood itself. Finally, the con-ception of a divinity who must continually interfere with his arrange-ments in order to prove himself a governing force depended upon theimmutability of different manifestations of life. This was the one re-maining strand. Publicists of the school of theological science rushed tohang upon it, and of course they hanged themselves with it. In Sedgwick'sview,Geology, like every other science when well interpreted, lends its aid to naturalreligion. It tells us, out of its own records, that man has been but a few yearsa dweller on the earth; for the traces of himself and of his works are confinedto the last monuments of its history. Independently of every written testimony,we therefore believe that man, with all his powers and appetencies, hismarvellous structure and his fitness for the world around him, was called into

38 CHARLES COULSTON GILLISPIE—being within a few thousand years of the days in which we hve not by atransmutation of species, (a theory no better than a phrensied dream), butby a provident contriving power. And thus we at once remove a stumbhngblock, thrown in our way by those who would rid themselves of a prescientfirst cause, by trying to resolve all phenomena into a succession of constantmaterial actions, ascending into an eternity of past time.^^Lyell, said the catastrophists, by dramatizing the necessity for getting fromone form of life to another and for explaining the unique character andrecent appearance of man, had offered the final proof for the incessantand ubiquitous application of God's creative powers to a universe whichHe had ordained, and the natural laws of which were few, perfect, andsimple; beneficent when properly understood; and unchangeable (exceptby God). In the 1830's, however, no one, not even Lyell, pressed the argumentto its logical conclusion. It will have been noticed that the anti-Mosaicschools also labored under the conventional obligation to point out howtheir larger understanding put God's works into a more sublimely neces-sary focus than the puerile and unscientific approach of Neptunist orcatastrophist. Further, there were certain received empirical boundarieswhich Huttonians and uniformitarians themselves never thought to ques-tion. Playfair and Smith admitted a flood; Lyell's 1830 man was recentlycreated and his animal species unique and more permanent than theprogressive creative installments on which Sedgwick took insecure refuge.Even the attacks, then, upon the theories of religious materialism didnot spring from a point of view fundamentally opposed to the idea ofapprehending the divine through the sort of manifestations which guidean engineering project. Vulcanism and uniformitarianism were simplyfurther stages in the retreat from the rigorous fundamentalism of Kir-wan and from the philosophic inspiration of Priestley. NOTES 1. Cuvier, Theory of the Earth, p. 12. 2. Lyell, Principles of Geology, I, 164-165. 3. Quoted in Geikie, Founders of Geology, p. 404. 4. By 1830, the differences over the interpretation of river valleys in particular had almost reached the proportions of a major issue. Two incipient schools, \"Fluvialist\" and \"Diluvialist,\" had developed and had prepared the positions which uniformitarian and catastrophist would occupy once Lyell made the disagreement explicit and funda- mental. For the fluvialist papers and the immediate empirical background of the uniformitarian theory, see, for example, P.G.S., I, 89-91, 170-171; T.G.S., 2d series, II, 195-236, 279-286, 287-292, 337-352. For the anticipatory diluvialist counter- attack, see P.G.S., I, 145-149, 189-192; T.G.S., 2d series, I, 95-102; 11, 119-130. 5. Fleming, \"The Geological Deluge, as Interpreted by Bacon, Cuvier, and Professor Buckland, Inconsistent with the Testimony of Moses and the Phenomena of Nature,\" Edinburgh Philosophical Journal, XIV (1826), 205-239, p. 208. 6. Ibid., pp. 209-215. Like many ex-Wernerians, Fleming had turned to zoology after

THE UNIFORMITY OF NATURE 39 \"geognosy\" became discredited. His chief work, Philosophy of Zoology, stood very firmly indeed upon the \"real existence\" of species in nature. 7. Scrope, Considerations on Volcanoes, pp. iii-ix, 242-243; Geology of Central France, pp. vii-viii, 197-213. For evidence of some concessions to the prevailing catastrophist theories, see the former of these titles, pp. iv-v, 215-218. 8. K. M. Lyell, Life of Charles Lyell, I, 163: Lyell to his sister, 4 December 1825. 9. Ibid., I, 170: Lyell to his father, 10 April 1827. See also II, 6-7: Lyell to Whewell, 7 March 1837. 10. 'Ibid., II, 6-7; Lyell, Principles of Geology, III, vii-xviii. 11. Lyell, Principles of Geology, I, 72. 12. Ibid., Ill, 1-6. 13. Ibid., 1, 144. 14. Ibid., pp. 63-65.15. [W. H. Fitton], \"Mr. Lyell's Elements of Geology,\" Edinburgh Review, LXIX (1839), 406-466. The Elements of Geology was a condensation and popularization of the Principles. On the question of Lyell's debt to Hutton, see V. A. Eyles, \"James Hutton (1726-1797) and Sir Charles Lyell (1797-1875),\" Nature, CLX (1947), 694-695.16. K. M. Lyell, Life of Charles Lyell, I, 269: Lyell to Scrope, 14 June 1830.17. Lyell, Principles of Geology, I, 76-82.18. Ibid.,p. 104.19. Ibid., Ill, 52-61.20. Though he did not think himself guilty of violating it, Lyell would have agreed with Sedgwick's canon, promulgated in criticism of the Principles: \"The language of theory can never fall from our lips with any grace or fitness, unless it appear as the simple enumeration of those general facts, with which, by observation alone, we have at length become acquainted\" (\"Presidential Address\" [1831], P.G.S., I, 302).21. Lyell, Principles of Geology, III, 272-273.22. Ibid., Ill, 270. See also I, 89.23. Ibid., Ill, 271-272.24. Ibid., p. 272.25. Ibid., II, 179.26. Ibid., -p. 1.27. Ibid., pp. 2-35.28. Ibid., p. 65.29. Ibid., p. 124.30. Ibid., pp. 179-184.31. Ibid., p. 270.32. Ibid., pp. 156-157.33. Ibid., 1, 145.34. Ibid., quoted from Sir Humphry Davy, Consolations in Travel, dialogue iii.35. Lyell, Principles of Geology, I, 145.36. Ibid., pp. 145-153.37. Ibid., pp. 155-156.38. Ibid., p. 156.39. K. M. Lyell, Life of Charles Lyell, I, 271 : Lyell to Scrope, 14 June 1830.40. Ibid., pp. 309-311: Lyell to Scrope, 9 November 1830.41. Lyell, Principles of Geology, I, 65.42. Ibid., pp. 65-66; on Voltaire and geology, see also White, Warfare of Science with Theology, 1,229.43. K. M. Lyell, Life of Charles Lyell, I, 271 : Lyell to Scrope, 14 June 1830.44. Ibid., p. 263: Lyell to his sister, 26 February 1830.45. Ibid., p. 173: Lyell to Mantell, 29 December 1827. See also Mantell, Journal, p. 75 (12 March 1830).46. K. M. Lyell, Life of Charles Lyell, I, 273: Lyell to Scrope, 25 June 1830.47. [Scrope], \"Lyell's Principles of Geology,\" Quarterly Review, XLIII (1830), 411-469. For Lyell's satisfaction, see K. M. Lyell, Life of Charles Lyell, I, 309-311: Lyell to Scrope, 9 November 1830.

40 CHARLES COULSTON GILLISPIE48. For a somewhat highly colored account of the theological opposition, both in the 1830's and later, see T. H. Huxley, \"The Lights of the Church and the Light of Science,\" in Science and Hebrew Tradition, volume VI of Collected Essays (New York, 1894), pp. 201-238.49. See, for example, Sedgwick, \"Presidential Address\" (1831), P.G.S., I, 304; Whewell, History of Inductive Sciences, III, 616-617; and see also Whewell's remarks in his review in the British Critic, IX (1831), 180-206, especially pp. 184-186, 202-204.50. Two vols.; London, 1839. Nor did Murchison's reviewer in the Edinburgh Review make any application of the work to interpretative controveries (LXXIII [1841], 1-41).51. Lyell, Principles of Geology, I, 76.52. For the first three months, volume I of the Principles, of which 1500 copies were printed, sold fifty copies a week. After this, sales, instead of declining, picked up enough to necessitate a second edition, of which Murray expected to sell one thousand copies in a year, but which in fact was bought up before that. In 1835, a third edition of the whole sold 1750 copies in ten months, and a fourth edition of 2000 was sold out in 1836 (K. M. Lyell, Life of Charles Lyell, I, 311-312, 383, 449, 464).53. For example, W. D. Conybeare, who headed the catastrophist counterattack: \"The great interest of this treatise seems to me to arise from its necessary tendency to force the current of scientific attention ... to certain points of theoretical inquiry, for the investigation of which the science has been for some time growing more and more mature\" {Philosophical Magazine, VIII [1830], 215). See also Whewell in the BrifishCrific, IX (1831), 180.54. Sedgwick, \"Presidential Address\" (1831), P.G.S., I, 302.55. K. M. Lyell, Life of Charles Lyell, I, 316-317: Lyell to Mantell March, 183L56. Mantell, Journal, pp. 122, 129 (1 May and 13 November 1835).57. The Geology of the South-East of England (London, 1833); The Wonders of AGeology; or, Familiar Exposition of Geological Phenomena (4th ed.; 2 vols.; London, 1840); and The Medals of Creation; or. First Lessons in Geology, and in the Study of Organic Remains (2 vols.; London, 1844).58. Illustrations of the Geology of Sussex (London, 1822).59. Mantell, Geology of the South-East of England, p. 1 5. In the terminology of diluvialist geology in the 1820's, materials more recent than tertiary formations were classified as alluvial and diluvial. The former means loose, superficial accumulations deposited by the mechanical action of surface water since the time of the retreat of the sea. The latter refers to materials deposited during a major inundation.60. Mantell, Wonders of Geology, I, 115-116.61. I&zd.,pp. 69-77, 114.62. Ibid., pp. 5-7.63. The reference is to Buckland's Bridgewater Treatise (see above, p. 212)64. Mantell, Wonders of Geology, II, 115-116.A65. Geological Manual (Philadelphia, 1832 [1st ed.; London, 1831]); and How to Observe (London, 1835). For De la Beche's work in establishing the Geological Survey, see F. J. North, \"Geology's Debt to Henry Thomas de la Beche,\" Endeavour, III (1944), 15-19.66. De la Beche, Geological Manual, p. 32.67. De la Beche, Resedrc/ies in Theoretical Geology (London, 1834), pp. 240-241.68. Geological Manual, pp. 131, 158-165, and passim; see also his \"Notes on the Ex- cavation of Valleys,\" Philosophical Magazine, VI (1829), 241-248; \"Notes on the Formation of Extensive Conglomerate and Gravel Deposits,\" Ibid., VII (1830), 161-171; and an anonymous criticism of several of his papers, ibid., pp. 189-194.69. K. M. Lyell, Life of Charles Lyell, I, 317-318, 330, 444; Geikie, Life of Murchison, I, 203, 266-267.70. K. M.LyeW, Life of Charles Lyell, I, 317-318: Lyell to his sister, 7 April 1831.71. Charles Daubeny, \"On the Diluvial Theory, and on the Origin of the Valleys of XAuvergne,\" The Edinburgh New Philosophical Journal, (1830-31), 201-229, pp. 204-205.72. K. M. Lyell, Life of Charles Lyell, I, 312: Lyell to his sister, 14 November 1830.