An atmospheric phenomenon is considered as 'explained' when we have succeeded in deducing it on the basis of accepted principles of physics. (H. Ertel, Methods and problems of dynamical meteorolo gy,p. l) Until recently, noctilucent clouds were regarded merely as a curious atmos pheric phenomenon, the occurrence of which aroused only limited scientific attention. However, in the last two decades the interest they have been given has markedly increased. The clouds, usually pale blue in colour, may be seen on a clear night at high latitudes. Typical examples are illustrated in the book. Clouds looking like these in daytime would be classified as cirrostratus. What sets noctilucent clouds apart is their occurrence in the middle of the night, their very obvious pale blue colour, and their disappearance into the dawn close to the onset of civil twilight when the Sun is 6 Degrees below the horizon. as being set apart from ordinary Noctilucent clouds were first recognized clouds in 1884/1885 and in a series of sightings that followed their return in the summer of 1885. That year marked the beginning of observations and the interpretation of twilight phenomena. The impetus came from the extraordi nary Krakatoa eruption, which was not only one of the most spectacular volcanic eruptions in recorded history, but which also turned out to be a startling event in atmospheric science with repercussions even in our time.

The last decade has seen a remarkable increase in the application of geomorphology for numerous projects and investigations. Geomor phology is now viewed as an indispensable partner of engineering and geology in the world of applied science. For a discipline with few independent theories of its own, geomorphology has become a cosmopolitan science, drawing on many topics from allied sciences. To compile a list of successful and viable applications and contribu tions would be an arduous chore, if not an impossible task. Instead we have compiled a set of invited papers that represent some of the practical developments and uses of geomorphology over the past de cade. Such a compilation of papers will reflect our own back grounds, biases, associations, and personal and professional expe riences. We make no apologies for the topics omitted, but recognize that this volume could be prohibitively large if all the subdivisions of geomorphology were equally and fully covered. Our goal in assembling the papers for this volume was to empha size the concepts, principles, and applications of geomorphology. While techniques, procedures and practical applications are stressed, the reason for each investigation is as important as the method em ployed. This book, therefore, represents the methods used and reasons for applying geomorphology. Where case studies are used, they serve as examples that can be applied in related situations, similar settings and other locations. The authors have successfully addressed this goal in a broad selection of chapter topics."

The contributions published in this volume are the re- sults of the NATO Advanced Research Workshop "Improvement of Joint Interpretation of Geophysical and Geological Data", which took place in Gradisca d'Isonzo in October 1987 and February 1988. Modern computer techniques were applied for geoscien- tific studies in a new dimension. 45 scientists from 7 Euro- pean countries, Canada and the united states of America par- ticipated in the workshop. Interactive discussions and modeling improved the understanding of the very complex structure of the investigated area. We thank all contributors, but especially those pub- lishing in this volume, for their active participation to ensure the success of the meetings. Not to forget to mention the groups of assistants from the Istituto di Minere e Geo- fisica Applicata of the University of Trieste and from the Institute of Geophysics of the Freie Universitat Berlin. Many thanks for their help around the clock. However, a major prerequisite for this success was given by the hospitality of the international Centre for Applied Sciences (ICAS) in the wonderful restored ancient pallazzi Torriani and Pretuna of the town of Gradisca d'Isonzo. Thus, we are thankful to the president of ICAS, Dr. H.R. Dahlafi, and to the town of Gradisca d'Isonzo, especially to the mayor, Signore Travan. The studies carried out in Gradisca d'Isonzo had been supported by a grant of the NATO Scientific Affairs Division and we express our thanks to Dr. L. da Cunha as a steady partner in the background.

Between the mid-seventeenth century and the early nineteenth century there developed in Britain a range of empirical and increasingly secular sciences concerned with the earth. This book presents a detailed account of how this development led to the creation of a complex socio-intellectual fabric of methods, ambitions, facts and ideas which took on the nature of a distinctive, self-sustaining discipline: 'geology'. During this period the criteria for a proper science of the earth were continually reassessed and the earth as an object of science was radically reinterpreted. In his account of this transformation, Dr Porter treats science as an integral but distinct part of the spectrum of man's intellectual and social activities. His account thus illuminates the nature of science and scientific knowledge as a dynamic intellectual, social and cultural enterprise. The book will be of interest not only to historians and philosophers of science but also to social historians and geologists.

The case history approach has an impressive record of success in a variety of disciplines. Collections of case histories, casebooks, are now widely used in all sorts of specialties other than in their familiar appli cation to law and medicine. The case method had its formal beginning at Harvard in 1871 when Christopher Lagdell developed it as a means of teaching. It was so successful in teaching law that it was soon adopted in medical education, and the collection of cases provided the raw material for research on various diseases. Subsequently, the case history approach spread to such varied fields as business, psychology, management, and economics, and there are over 100 books in print that use this approach. The idea for a series of Casehooks in Earth Science grew from my experience in organizing and editing a collection of examples of one variety of sedimentary deposits. The prqject began as an effort to bring some order to a large number of descriptions of these deposits that were so varied in presentation and terminology that even specialists found them difficult to compare and analyze. Thus, from the beginning, it was evident that something more than a simple collection of papers was needed. Accordingly, the nearly fifty contributors worked together with George de Vries Klein and me to establish a standard format for presenting the case histories."

Drilling deep into the earth holds a fascination for earth scientists derived in part from the fact that the drill hole is the ultimate test of a hypothesis. When surface exploration methods have been fully uti lized and all the geological inferences drawn about the structure be neath the surface, we must finally drill to sample directly the third dimension of the crust of the earth. The drill is thus the tool of choice of the energy and minerals re sources industry. Because of high cost, drilling has been only sparing ly used for solving fundamental problems in the earth sciences. But now, having used the quite sophisticated methodology of exploration geophysics, the exciting structural detail emerging from seismic re flection profiling in particular has led several nations to begin a major program of scientific drilling to solve some of the major prGb lems in the earth sciences. Hhat is described in this volume are the blueprints for national re search programs in France, the Federal Republic of Germany, Japan and the United States. The Soviet Union has already embarked on a major drilling effort, the results of which are soon to be published. Results, of course, are still few, and this first volume is more concerned with the problems to be solved."

This book comprises the main results of the Scenario (Support on Common European Strategy for sustainable natural and induced technological hazards mitigation) project, funded as a Specific Support Action under the VI FP. This book addresses three main needs: first, it constitutes an assessment of the situation of Europe as far as natural na-tech risks are considered; second, it suggests future research themes to be opened of widened so as to tackle new and emerging threats as well as changes in the potential response to risk governance, in order to improve the way scientific and technical expertise informs decision making regarding all fields of mitigation, ranging from structural to non structural measures, such as training, education and land use planning.

The Sonderforschungsbereich (SFB) 48-Gottingen, a Special Collaborative Programme of the Deutsche Forschungsgemeinschaft, was one of the first of such programmes. It was launched in 1969 under the general title "Evolution, composition and distinctive characteristics of the Earth's crus t, particularly in geosynclinal regions" ("En twickl ung, Bestand und Eigenschaften der Erdkruste, insbesondere der Geosynklinalraume"). Its activities were promoted for eleven and a half years and it came to its end at the expiration of 1980. We have he re a comprehensive report of the results it has reached, of the questions that remain open, and the new questions that have been raised. Special Collaborative Programmes ("Sonderforschungsbereiche") involve groups of scientists who have join- ed together with the approval of their university for joint research in which the university recognizes that their research has common ground deserving support for a longer period of time. Significant progress in science is increasingly dependent on the close collaboration of scientists from several disciplines. The Special Colla- borative Programmes were created in order to provide better conditions and structures for multi- nad interdisciplinary research. It seemed prom- ising to mount special support, in terms of both material and personnei, for the geologically orientated research programme proposed from Gottin- gen, which envisaged interdisciplinary research into the nature of two different intracontinental orogens, research involving Geology-palaeon- tology, Sedimentology, Sedimentary Petrography, Geochemistry, Petrology, Geochronology and Geophysics.

Shows the bedrock geology. Information for superficial deposits may be omitted or shown only in outline.

In Plants and the K-T Boundary, two of the world's leading experts in palynology and paleobotany provide a comprehensive account of the fate of land plants during the 'great extinction' about 65 million years ago. They describe how the time boundary between the Cretaceous and Paleogene Periods (the K-T boundary) is recognized in the geological record, and how fossil plants can be used to understand global events of that time. There are case studies from over 100 localities around the world, including North America, China, Russia and New Zealand. The book concludes with an evaluation of possible causes of the K-T boundary event and its effects on floras of the past and present. This book is written for researchers and students in paleontology, botany, geology and Earth history, and everyone who has been following the course of the extinction debate and the K-T boundary paradigm shift.

In October 1986 the German Minister for Research and Technology (Bundesminister fUr Forschung und Technologie), Dr. H. Riesenhuber, officially announced that the super-deep borehole of the Continental Deep Drilling Program of the Federal Republic of Germany (KTB) would be drilled in the Oberpfalz area of Northern Bavaria. The site selection was based on a recommendation from the Deutsche Forschungsgemeinschaft (DFG) made after an evaluation by the Project Management of the technical and financial risks involved. This decision was preceded by a conference held from September 19 to 21, 1986 in Seeheim/Odenwald at which the results of the site studies in the Oberpfalz and the Schwarzwald were presented and thoroughly debated. The models and scientific targets resulting from these investigations formed the basis for a vote by the DFG Senate Commission for Geoscientific Interdisciplinary Research which was taken immediately after the conference. After evaluation of all scientific and technical aspects, the members of the commission voted almost unanimously for the Oberpfalz site. It was, ho",'ever, strongly emphasized that both locations had a wealth of attractive research objectives and that despite clear-cut differences in some major aspects scientifically the two could be regarded as more or less equivalent. Both'locations would be excellent sites for research drilling and would certainly cor.

Algae and Algal Carbonates are of interest to geo- and bioscientists because of the significant interactions between algal life and environ- ment. Much information about systematical, morphological and eco- logical data of fossil algae has been accumulated during the last two decades. Facies interpretation, sedimentology, and biostratigraphic correlations, as well as speculations about Precambrian ecosystems have received new impulses from the detailed study of Recent algae and their fossil counterparts. During the First International Symposium on Fossil Algae, orga- nized by the Institute of Paleontology of the University Erlangen- Niirnberg in October 1975, about 130 scientists were able to discuss the present status of knowledge; 55 lectures were given, 37 of which now have been chosen for publication. Some of these articles comprehend fundamental reviews on algal groups and algal constructions, such as Monty on the stromatolites, Herak et al. and the "French Group" on the dasyclads, and Wray and Poignant on the Paleozoic and Mesozoic red algae. Other articles deal with the biology and morphology of blue-green algae, with the arduous problem of the affinities of many algae and "pseudo-algae", with bio- metrical methods and with the ultrastructure of calcareous algae. A broad section of this book is reserved for some stimulating papers about the role of algae as facies indicators and sedimentological factors in Recent and Ancient environments. Thanks to the gratefully accepted co-operation of many collegues, we hope this book may offer a good cross-section through main trends of recent algal research.

together with contributions by invited geoscientists The Central Andes, whose orogenic activity is so impressively documented by recent volcanism and and counterparts from other countries, during a workshop held in Berlin, 23-25 May 1990. A great earthquakes, have always attracted the attention of geoscientists. This interest became even more accen number of the papers presented at this workshop are tuated since, a quarter of a century ago, Plate included in this volume. While most of the chapters Tectonics became the basis for the New Global refer regionally to the segment of the southern Andes Tectonics concept, in which this huge mountain range mentioned above, others treat general aspects or deal was the most spectacular example of an active conti with Andean regions farther south, thus showing not only that the structures of this mountain range can be nental margin. Thus, in addition to the continuing research work by South American and foreign geo followed to more distant parts but also that there are scientists dedicated mostly to regional and economic significant structural variations along strike. problems, a great number of special research pro Like other books which originate from workshops grammes were initiated aiming at a better understand and are comprised of contributions from many ing of the processes acting at a convergent plate authors, also this one cannot give a complete and margin. well-balanced view of the scientific subject dealt In 1982, the earth science institutes of the Freie with, in this case the southern Central Andes.

The present book is devoted to the study of the deep Earth's interior structure, one of the most important problems of Earth sciences today. The drilling of the Kola superdeep well inaugurated a new stage in the study of the Precambrian continental crust. The well was sunk in the northeastern part of the Baltic Shield, in an area where the Precambrian ore-bearing structures, typical of the ancient platform basements, are in juxtaposition with each other. To the present the well has been drilled to a depth of 12 km, has traversed the full thickness of the Proterozoic complex and a considerable part of the Archean stratum, and is still be ing worked on. This book reviews the principal results of investigations to a depth of 11,600 m; these are described in three sections: geology, geophysics, and drilling. The book begins with a general review of the history, the present state of knowledge, and trends of further investigations in the field of study of the Earth's interior and superdeep drilling. The first section of the book considers the geology of the vicinity of the Kola superdeep well and describes its geological section based on a detailed examination both of the cores and the near-borehole area."

The principal aim of the present work is to understand the evolution of halogenesis in the Paleozoic. To succeed in the study it was neces- sary to make a general and systematic synthesis of data available on world-wide Paleozoic halogenic deposits and describe all known eva- porite basins. This study succeeds the monograph Paleozoic Salt For- mations of the World (Zharkov 1974a). The history of Paleozoic salt accumulation is based chiefly on evidence presented in the above monograph; this work should be considered as its direct continutation. The present work mainly aims at: (1) establishment of the num- ber of both salt and sulfate basins and salt and sulfate sequences formed therein in the Paleozoic; (2) determination of the stratigraphic position of salt and sulfate sequences in separate regions, their distant correlation and recognition of stages of evaporite sedimentation during the Paleozoic; (3) determination of the volume and areas of distribution of halite, potash, and sulfate sedimentation within basins and on continents through periods, epochs, and ages of the Paleozoic to single out epochs of the most intense evaporite sedimentation; (4) reconstruction of paleogeography of continents to recognize stages of evaporite accumulation and paleoclimatic zones of halogenic sedi- mentation in the Paleozoic; (5) understanding the evolution of eva- porite sedimentation in the Paleozoic. The nomenclature used in the book should be explained.

The fifth volume in this series is focused on the chemical and physical interactions between rocks undergoing metamorphism and the fluids that they generate and that pass through them. The recognition that such pro cesses can profoundly affect the course of metamorphism has resulted in a number of recent papers and we consider that it is time for a review by some of the interested parties. We hope our selection of contributors provides an adequate cross section and demonstrates some of the flavor of this rapidly developing field. A cursory examination of the volume will reveal that there are widely divergent opinions on the compositions of metamorphic fluids and on the ways in which they interact physically and chemically with the rocks through which they pass. Since our own views are extensively discussed in Chapters 4 and 8, we leave the reader to determine his own brand of the "truth. " We wish to thank D. Bird, S. Bohlen, D. Carmichael, G. Flowers, C. Foster, C. Graham, E. Perry, J. Selverstone, R. Tracy, J. Valley, and R. Wollast for their chapter reviews. Thanks are also due C. Cheverton for her editorial assistance, and the helpful staff at Springer-Verlag New York."

This book explores the basic principles and methods of paleomagnetology and gives a systematic description of paleomagnetic phenomena such as geomagnetic reversals, paleosecular variations, long-term intensity changes and apparent polar wandering paths. Special emphasis is laid on results obtained from research work done in the Soviet Union. Together with data from other parts of the world they allow the critical discussion of aspects of magnetostratigraphy, plate tectonics and accretion tectonics. In diesem Buch werden grundlegende Fragen der Palaomagnetologie und des Palaomagnetismus abgehandelt. Durch die Einbeziehung zahlreicher Daten aus der Sowjetunion werden Probleme der Magnetostratigraphie sowie der Platten- und Akkretionstektonik kritisch beleuchtet.

This series of monographs represents continuation on an inter national basis of the previous series MINERALOGIE UND PETRO GRAPHIE IN EINZELDARSTELLUNGEN, published by Springer Verlag. The voluminous results arising from recent progress in pure and applied research increase the need for authoritative reviews but the standard scientific journals are unable to provide the space for them. By their very nature, text-books are unable to consider specific topics in depth and recent research methods and results often receive only cursory treatment. Advanced reference volumes are usually too detailed except for experts in the field. It is often very expensive to purchase a symposium volume or an "Advances in . . . " for the sake of a specific review chapter surrounded by volume unrelated chapters. We hope that this monograph series will by pass these problems in fulfilling the need. The purpose of the series is to publish reviews and reports of carefully selected topics written by carefully selected authors, who are both good writers and experts in their scientific field. In general, the monographs will be concerned with the most recent research methods and results. The editors hope that the monographs will serve several functions, acting as supplements to existing text-books, guiding research workers, and providing the basis for advanced seminars. W. VON ENGELHARDT, Tiibingen July 1970 T. HAHN, Aachen R. RoY, University Park, Pa. J. W. WINCHESTER, Tallahassee, Fla. P. J. WYLLIE, Chicago, Ill. Preface Sub-series on "Isotopes in Geology.""

The past two decades have witnessed a revolution in the earth sciences. The quantitative, instrument-based measurements and physical models of. geophysics, together with advances in technology, have radically transformed the way in which the Earth, and especially its crust, is described. The study of the magnetism of the rocks of the Earth's crust has played a major part in this transformation. Rocks, or more specifically their constituent magnetic minerals, can be regarded as a measuring instrument provided by nature, which can be employed in the service of the earth sciences. Thus magnetic minerals are a recording magnetometer; a goniometer or protractor, recording the directions of flows, fields and forces; a clock; a recording thermometer; a position recorder; astrain gauge; an instrument for geo logical surveying; a tracer in climatology and hydrology; a tool in petrology. No instrument is linear, or free from noise and systematic errors, and the performance of nature's instrument must be assessed and certified. This has been the task of the research worker in rock and mineral magnetism."

You might well wonder why TFPC in Practice is a part of the Monographs in Visualization series. However, if you really think about typesetting, especially fine typesetting, you soon realize that in large part it is a visual art as well as a science. 'lEX's algorithms produce in almost all cases aesthetic results of the highest quality. On the other hand, occasionally one may want to insert some additional space before a subscript or superscript, or one may want to adjust the vertical spacing in a fraction. Fortunately Donald Knuth, the author of 'lEX, allows one to program such corrections easily where needed. The four volumes of Stephan von Bechtolsheim's long awaited TFPC in Prac tice present a comprehensive view of 'lEX. His thorough discussion of each aspect of 'lEX is liberally laced with cogent illustrative examples. Many of these exam ples represent complete, ready to use macros that enhance the capabilities of 'lEX. These examples are of particular interest to both the typesetter and the 'lEX programmer. The typesetter can often solve an immediate problem by ei ther using one of the examples directly or by making minor changes to adapt it to the problem at hand. The 'lEX programmer can use the examples, along with Stephan's detailed discussion, to increase both the depth and breadth of his or her knowledge of 'lEX. The value of the text is further enhanced by Stephan's concerted effort to explain the reasoning behind each topic or example."

This volume certainly is a Conference Proceedings, the Proceedings of the NATO Advanced Research Workshop (ARW) on "Unsaturated Flow in Hydrologic Modeling" held at "Les Villages du Soleil" near ArIes, France from June 13 to 17, 1988. Let me therefore acknowledge properly, at the very beginning, the gratitude of all the participants to the NATO Science Committee for its generous support and worthwhile goal of bringing together scientists of many countries to communicate and share their experiences. Particular thanks are extended to the director of the program, Dr. Luis Vega da Cunha for his interest and understanding. On the other hand this volume is also, and probably more so, a Textbook that fills a gap in the field of unsaturated flow. Many treatises on the subject present the theory in its different aspects. Hardly any explain in details how the different pieces can be put together to address realistic problems at the basin scale. The various invited contributions to the ARW were structured in a subject progression much as chapters are organized in a book. The intent of the ARW was to assess the current state of knowledge in "Unsaturated Flow" and its use in "Hydrologic Modeling Practice." In a sense the interest in fundamentals of unsaturated flow in this ARW was not just for the sake of knowledge but also and primarily for the sake of action. Can such fundamental knowledge be utilized for better management of the water resource? was the basic question.

Humic substances occur in all kinds of aquatic systems, but are particularly important in northern, coniferous areas. They strongly modify the aquatic ecosystems and also constitute a major problem in the drinking water supply.
This volume covers all aspects of aquatic humic substances, from their origin and chemical properties, their effects on light and nutrient regimes and biogeochemical cycling, to their role regarding organisms, productivity and food web organization from bacteria to fish. Special emphasis is paid to carbon cycling and food web organization in humic lakes, but aspects of marine carbon cycling related to humus are treated as well.

At the intersection of environmental science and human biology this book deals with dry ecosystems - aridity, droughts, wind and its influence on soils and regulation - the societies affected by these ecosystems, and the inventiveness of those living under these conditions. These environments are the basis of nomad existence, of irrigated agriculture and of the first civilisations dependent on streams. Changes in the modern epoch, the ever-increasing technology and demographic development show that environmental degradation and the socio-economic situation cannot be explained by just one factor. This book tries to answer the question whether long-lasting development is possible in dry environments.

Both the beauty and interest of fractures and fracture networks are easy to grasp, since they are abundant in nature. An example is the road from Digne to Nice in the south of France, with an impressive number and variety of such structures: the road for the most part, goes through narrow valleys with fast running streams penetrating the rock faces; erosion is favored by the Mediterranean climate, so that rocks are barely covered by meager vegetation. In this inhospitable and sterile landscape, the visitor can im mediately discover innumerable fractures in great masses which have been distorted by slow, yet powerful movements. This phenomenon can be seen for about 100 kilometers; all kinds of shapes and combinations are repre sented and can be observed either in the mountain itself or in the man-made cliffs and excavations, resulting from improvements made to the road. In the same region, close to the Turini Pass, a real large scale hydrody namic experiment is taking place -a source which is situated on the flank on the mountain, has been equiped with a tap; if the tap is open, water flows through the tap only, but when it is closed, then the side of the mountain releases water in a matter of seconds. Other outlets are also influenced by this tap, such as a water basin situated a few hundred meters away."

This monograph was begun with two objectives in mind. The first was to provide a review of research involving the application of neodymium isotopic measurements to pro blems in earth science. In the process of organizing to do this, I realized that the research in this field had produced a need for an updated review of the underlying paradigms. This need had arisen because of the special properties of the samarium-neodymium isotopic system, and because the research had transgressed the traditional boundaries be tween the subfields of earth science. Without such a review, the significance of the results seemed likely to remain un necessarily obscure to interested scientists from related disciplines. Consequently, the second objective became the provision of a theoretical framework for the application of neodymium isotopic studies. Much of what this contains is not new, but it is drawn together here for the first time. At the time the writing was initiated, the literature of the field was still relatively limited. Over the past 5 years it has grown enormously. Considering the rate at which the writing progressed, it became clear that this could not be a fully up-to-date review and still reach completion. The selection of material for the review sections is biased toward earlier studies. Part I presents most of the background information."