ALBERT

Description / Table of Contents: The editors present a state-of-the-art overview on the Physics of Space Weather and its effects on technological and biological systems on the ground and in space. It opens with a general introduction on the subject, followed by a historical review on the major developments in the field of solar terrestrial relationships leading to its development into the up-to-date field of space weather. Specific emphasis is placed on the technological effects that have impacted society in the past century at times of major solar activity. Chapter 2 summarizes key milestones, starting from the base of solar observations with classic telescopes up to recent space observations and new mission developments with EUV and X-ray telescopes (e.g., STEREO), yielding an unprecedented view of the sun-earth system. Chapter 3 provides a scientific summary of the present understanding of the physics of the sun-earth system based on the latest results from spacecraft designed to observe the Sun, the interplanetary medium and geospace. Chapter 4 describes how the plasma and magnetic field structure of the earth`s magnetosphere is impacted by the variation of the solar and interplanetary conditions, providing the necessary science and technology background for missions in low and near earth`s orbit. Chapter 5 elaborates the physics of the layer of the earth`s upper atmosphere that is the cause of disruptions in radio-wave communications and GPS (Global Positioning System) errors, which is of crucial importance for projects like Galileo. In Chapters 6-10, the impacts of technology used up to now in space, on earth and on life are reviewed.

Description / Table of Contents: The book gives a general overview of recent approaches to debris flows. Problems of both occurrences and dynamics of debris flow are treated, taking into account new results from theoretical and experimental research and field observations. Finally, the functioning of the main control devices are reconsidered in the light of the state of the art.

Description / Table of Contents: This book, which is divided into three parts, gives a state-of-the-art report on technical developments in instrumentation and on theoretical advancements in acoustic remote sensing. It explains the utilization of acoustic techniques in studies related to the structure of the lower atmosphere and oceans and discusses various atmospheric and oceanic applications. The potential and limitations of acoustic remote sensing are also described. This book will be useful to researchers, graduate students, and teachers interested in the structure of the atmosphere and oceans.

Description / Table of Contents: This book presents many types of tidal phenomena. The contributions evolved from a seminar in Oberwolfach, Black Forest, where German experts on tidal research met in October 1994 to present their views and experience to interested graduate students and scientists in an informal way. The seminar focused on earth tides, tides of the atmosphere and the oceans, including solar-induced variations of the magnetic field and climate, and tidal phenomena in the planetary system and universe. This book has an introductory character, but some contributions describe the state of the art in tidal research.

Description / Table of Contents: Especially due to the increasing environmental problems there is a need to collect as many data as possible in the upper atmosphere. This book serves as a general multidisciplinary guide and introduction for a more effective use of the large amount of now available data from the Earth's atmosphere. It also shows the problems of the use of large amounts of time series data - for basic science as well as for environmental monitoring - and the related information systems. The book is aimed for scientists and students interested in the Earth's atmosphere which is vital for the understanding of environmental changes in the global system Earth

Description / Table of Contents: PREFACE The aim of this volume is two-fold. At the more pragmatic level, it is to help answer the many questions about the structure of the Pacific continental margin of North America, which have arisen over the years as a result of continuing field mapping and geophysical surveys. The second objective is methodological - to illustrate the irreplaceable role of geological information among the various data sets used in earth-science studies. The need to address these issues became apparent to the author during the several years he spent taking part in geological and geophysical studies on the west coast of Canada. All too often, results of geologic field mapping disagreed with tectonic predictions from too-straightforward local applications of global plate reconstructions, which due to their generality do not always take a full account of specific character of particular regions. To be sure, the global approach has during the last q~/artercentury greatly expanded the vision of geoscientists, previously restricted to continental regions. However, a negative by-product of this expansion has been a decline of attention paid to local information, as tectonic studies have increasingly relied on simply fitting the development of a particular region into this or that prefabricated tectonic template. Direct geological observations have limitations of their own. The observer in most cases deals with products of geologic processes, rather than with the processes themselves. Field mapping provides local information, and many years of effort are needed before a regional overview becomes possible. Geologic mapping is restricted to the ground surface, and even the deepest drillholes cannot sample more than the outermost shell of the Earth. The factual side of geologic mapping is usually limited to determination of rock types and their relationships in areas of exposure. Conclusions about the three-dimensional structure of a region and its evolution are still mostly inferential. Broad incorporation into geological studies of geophysical data, assisted by ever-more-sophisticated modern computers, provides a huge volume of information unobtainable in other ways. Geophysical methods quickly afford regional coverage or images of the Earth's deep interior. Geophysical methods have prompted the application in geological sciences of methodologies borrowed from exact sciences, such as mathematics and physics. Particularly important has been quantitative modeling, which allows a scientist to use the known parameters of a system to predict others. But in taking this approach too far, one encounters a dangerous pitfall. A model is a simplified representation of a natural phenomenon. The quality of this or that representation is relative, and a representation is never perfect. To incorporate all characteristics of a geologic phenomenon, in a parametrized form, into a numerical or physical imitation is impossible. This requires one to rely on simplifying assumptions, and a model is no better than the assumptions at its base. Unrealistic assumptions lead to unrealistic models. When a disagreement arises between model predictions and observations - such as those from geologic field mapping - a modeler may be tempted to downplay the differences or the significance of the offending observations. It becomes tempting to underestimate the role of an experienced geologist as a principal arbiter of the realism of a model. But it is geological data and geological control that provide the ultimate means of testing abstract models. From this methodological position, the present study of the western North American continental margin is organized as follows: 1. Geological information, available from field mapping and drilling, is gathered and summarized. 2. Current geophysical models for this region are considered, with particular attention to their underlying assumptions. 3. The available data, geological and geophysical, are synthesized into an internally consistent geologic-evolution concept. 4. This concept is tested by comparison with direct geological observations from field mapping and drilling. Because most current data sets and models cover northwestern Washington and western British Columbia, particular attention was paid to these areas. Fortunately, these areas contain many keys that help understand the structure of the entire western North American continental margin, which has baffled scientists for decades. The author does not claim to have resolved all these problems, but he does believe he has made a useful contribution to understanding continental-oceanic plate interrelations at this continental margin. Rigidity of lithospheric plates is a critical assumption in current models of plate evolution. The lithophere of a plate is created at spreading centers manifested in the global system of mid-ocean ridges. It moves away from the place of its birth towards boundaries with other plates, with which it can interact in a variety of ways. Some interactions are of strike-slip type, with two plates simply sliding past each other. However, to compensate for the creation of new lithosphere at spreading centers, older lithosphere at some plate boundaries descends into the mantle as it is overriden by other plates. At such plate boundaries lie subduction zones. If both regimes occur along a single plate boundary, the transition between them must be abrupt. Unless it can be tied to a change in orientation of the boundary, it must be associated with a junction of not two, but three different plates. Such a template was used to interpret the structure and tectonic evolution of the western North American continental margin in the late 1960s and thereafter (Atwater, 1970; McManus et al., 1972; Barr and Chase, 1974; Riddihough and Hyndman, 1976). To satisfy the principles of rigid-plate tectonics, both regimes have to exist along this continental margin. Also needed in rigid-plate reconstructions is a plate triple junction somewhere between the areas of proven ongoing subduction (in Oregon and southern Washington) and transform plate motion (along the southeastern Alaska margin; Atwater, 1970; McManus et al., 1972). Such a triple junction has been placed off Queen Charlotte Sound offshore British Columbia (Keen and Hyndman, 1979; Riddihough et al., 1983), where a spreading center has been postulated between the Pacific and Explorer oceanic plates (Hyndman et al. 1979; Riddihough, 1984). Off northern Vancouver Island, a transform boundary between the Explorer and Juan de Fuca oceanic plates has been postulated, but both these plates are assumed to be subducting beneath Vancouver Island (Hyndman et al., 1979; Riddihough and Hyndman, 1989)o With the assumed universality of the rigid-plate model, "broad similarity" has been suggested between the geology of western Oregon and that of western British Columbia, and the Cascadia zone of active subduction has been extended as far north as the mouth of Queen Charlotte Sound (Riddihough, 1979, 1984). An accretionary sedimentary prism (Yorath, 1980) - or even an accretionary complex containing several exotic "terranes" (Davis and Hyndman, 1989) - has been postulated off Vancouver Island. Geological observations onshore and offshore (Shouldice, 1971; Tiffin et al., 1972) have come to be considered too "surficial" to be of major consequence for large-scale tectonic modeling (Yorath et al., 1985a,b; Yorath, 1987). Variants of the principal geophysical model for this area during the last decade (Clowes et al., 1987; Hyndman et alo, 1990; Spence et al. 1991; Yuan et al., 1992; Dehler and Clowes, 1992) have become increasingly distant from geological observations. As new model variants emerged, they were checked for internal consistency, compatibility with neighboring local models and fidelity to the overall assumed tectonic picture. However, detailed geological work continued, and many of its results proved incompatible with the conventional wisdom (Gehrels, 1990; Babcock et al., 1992, 1994; Allan et al., 1993; Lyatsky, 1993a). Importantly, questions arose about the applicability in this region of the conventional, simple rigid-plate assumption, as it was shown to be unable to account for all the geological and geophysical peculiarities in some areas (Carbotte et al., 1989; Allan et al., 1993; Davis and Currie, 1993). New solutions were made necessary by new findings and by rediscovery of forgotten old data (see Lyatsky et al., 1991; Lyatsky, 1993b). Without aiming to resolve all the outstanding debates, tectonic implications of the geologic mapping and drilling results in this region are considered in the following chapters. These results are integrated with geochemical and geophysical data. Interpretations of these data, made by this author and by other workers, are verified by geological observations and by geologically plausible extrapolations from these observations. In searching for solutions consistent with all the information, the author has restricted himself to analyzing continental-crust structures along this continental margin. He believes, however, that future models for the offshore regions of the northeastern Pacific should consider the results obtained herein.

Description / Table of Contents: The study of calcareous bedding rhythms has become an important field in Geology. Often these bedding rhythms are simply interpreted as representations of primary climatic cycles without showing the effects of any appreciable diagenetic overprinting. This study, however, deals predominantly with the diagenetic processes which are usually large and affect both the amplitude and rhythm of carbonate oscillations. The purpose of this textbook is two fold. First, it intends to provide a better understanding of the processes of diagenetic bedding. Secondly, this new approach allows one to quantify and to understand diagenesis in terms of mass exchanges. This is possible through the development of methods which combine chemical data with compaction measurements. These methods can be also used independent of the marl-limestone alternation problem.

Description / Table of Contents: PREFACE This volume contains a selection of papers presented and discussed at the COMTAGWorkshop on "Dynamics and Geomorphology of Mountain Rivers". COMTAG (Commission on Theory, Measurement and Application in Geomorphology) is a commission of the International Geographical Union (IGU). The meeting was held in the monastery of Benediktbeuern in the Bavarian Alps in June 1992. The main objective of the meeting was to review the most recent developments in research on river bed dynamics and bedload transport in mountain rivers. Questions of mountain torrent control and environmental protection were also addressed. The general theme of the meeting finds its appropriate scientific and spatial location in the long tradition of bedload transport studies carried out in the fluvially active German Alps, which are often affected by flood and mass movement hazards. The conference provided an impulse for discussions between researchers in the fields of mountain torrent hydrology, water resources management and bedload transport modelling. In the five years preceding the meeting the editors of this volume had headed a DFG (Deutsche Forschungsgemeinschaft) project on "Bedload transport and river bed adjustment in the Lainbach catchment" within the priority programme "Fluvial Geomorphodynamics in the late Quaternary". Results of the investigations and newly developed measurement techniques were introduced to the participants during the meeting and an excursion to the nearby Lainbach River. The meeting was attended by sixty four scientists from fifteen countries. Thirty four papers were presented in sessions on bedload transport in mountain torrents, measurement techniques of solid material transport, mass movements and sediment supply, river bed adjustment and roughness characteristics of steep mountain torrents, models of bedload transport, and catastrophic flooding. From a regional perspective the majority of the contributions dealt with the Alps with a special focus on investigations carried out at the northern fringe of the Alps. Most of the papers presented were submitted for publication, and selected papers have been included in this volume. The workshop was financially supported by the Deutsche Forschungsgemeinschaft, the Commission of the European Communities (Directorate General for Science, Research and Development), the Freistaat Bayern (Ministerium fOr Unterricht, Kultur, Wissenschaft und Kunst) and the US-Army Research and Development Standardization Group. The participants and the organizers are grateful for these grants. We thank the president of COMTAG, Asher Schick, for his friendly support during the preparation and organization of the workshop. We are also very much indebted to the Kathoiische Stiftungsfachhochschule M~nchen and the Salesianer Don Bo~cos, Benediktbeuern, who opened the rooms of the monastery of Benedikbeuern for scientific sessions and social events during the conference. The organization of the meeting would not have been possible without the help of the local and regional administration, water and forest authorities. We highly appreciate this assistance. In addition, the editors thank the Springer-Verlag for the inclusion of the conference proceedings in this series and the colleagues F. Ahnert, J. Bathurst, W. Bechteler, I. Campbell, P. Carling, N.J. Clifford, S. Custer, T. Davies, A. Dittrich, R. Ferguson, K. Garleff, M. Hassan, R. Hey, H. Ibbeken, J. Karte, H. Keller, D. Knighton, J. Laronne, M. Meunier, M.D. Newson, D. Oostwoud-Wijdenes, I. Reed, K.S.Richards, A. Scheidegger and W. Symader for their valuable contributions as reviewers of the manuscripts that were submitted for this volume.

Description / Table of Contents: INTRODUCTION Ecometry concerns measurements and interpretation of ecological data and relationships between data. It deals with most matters involved in the scientific aspects of the representativity and information value of samples and does not, in fact, concern statistical methods. In particular, ecometry can be regarded as an approach to obtain so-called load models and load diagrammes (effect-dose-sensitivity diagrammes), which are one of the aims/final products in aquatic environmental consequence analysis (H~- kanson, 1990; all these terms will be explained later on). This publication is meant to demonstrate what can and cannot be done using ecometric approaches. It must be emphasized at the outset that the main intention here is not to provide new radioecological knowledge on how Cs-137 is dispersed in aquatic ecosystems after the Chernobyl accident and is taken up in fish, but to use Cs-137 as a type substance and pike as a biological indicator to go through methods which should also apply to other types of environmentally hazardous substances (it could just as well have been substance X in ecosystem Y). As a secondary effect, we may also learn something about Cs-137. Several terms and methods, which have not been used earlier in the aquatic environmental sciences, e.g., ecometric analysis and dynamic modelling using moderators, will be discussed and defined...

Description / Table of Contents: PREFACE This monograph is a compendium of revised papers which were originally presented at the "Ron Mather Symposium on Four-Dimensional Geodesy", 28-31 March, 1989, held at the University of New South Wales, Sydney, Australia. The symposium had the enthusiastic support of the International Association of Geodesy and the Australian Academy of Sciences. The symposium served two purposes: to honour the achievements of the late Professor Ron S. Mather, the distinguished Australian geodesist who died in 1978, and to review and report on the latest developments in four-dimensional geodesy. Four-dimensional geodesy is a convenient term for those geodetic principles and techniques which yield position, gravity and their time variations. In the past geodesists have tended to think of the earth as a static body, save from occasional savage earthquakes or volcanic eruptions. So, why the need to coin the term "four-dimensional geodesy") Because it explicitly recognises that time is an integral part of understanding geodetic measurements. But let's first identify the scope of modern geodesy. Geodesy has traditionally been concerned with two separate, though closely related, topics: accurate positioning of objects on the earth's surface, and mapping the earth's external gravity field. These are still the fundamental tasks of geodesy, although the spheres of application have now extended into space. However, present and emerging geodetic measurement technologies for gravity field mapping and positioning are sensitive to defolTnations of the earth's surface and gravity field. Within the geodetic community, this new emphasis on accounting for the time-varying characteristics of position and gravity has fundamental principles; in particular the establishment and maintenance of appropriate global reference systems for geodesy. At the same time, there has been a growing recognition by the earth sciences in general of the important role of geodesy in studying earth deformations, as well as atmosphere and ocean dynamic phenomena. The geodetic measurements, for example, are taken over time scales of hours to decades, and occasionally to a century or longer. Though this is only a small part of the whole deformation spectrum, it is a very important one. Geodesy bridges the low frequency part of the spectrum available from geological observations, with the high frequency end observed from, for example, seismic instrumentation. It's role in atmospheric and oceanographic studies is as a unique, high precision remote sensing tool. The revolution in geodesy is not, however, restricted to the measurement technology only. It is true that without the advances of space geodesy and terrestrial metrology, the notion of four-dimensional geodesy is a rather academic one. These advances, which now reveal time-variable signals above the measurement noise level, have important implications for all geodetic activities. The geodetic activities we refer to can be identified as: experiment design and measurement processes; definition and maintenance of highly stabie geodetic reference systems; data analysis; and interpretation of position and gravity results. Ultra high precision measurements are of little use without sophisticated analysis tools to extract the small signals in the data. The interpretation of geodetic results will be in error if insufficient attention is paid to ensuring that the reference systems to which the results relate are themselves stable. Clearly four-dimensional geodesy is as much about concepts and principles, as about computers and geodetic equipment. This diversity is reflected in the papers selected for this book. They range over topics related to the modem measurement tools, the reduction and analysis techniques, to the interpretation of geodetic results within the context of problems currently being investigated in the earth sciences. We would like to thank the International Association of Geodesy and the Australian Academy of Sciences for sponsorship of the Symposium. Unisearch Ltd., the commercial arm of the University of New South Wales, was the managing agent, and staff members of the School of Surveying and of Unisearch Ltd. were involved in the organisation of the Symposium. We would like to gratefully acknowledge these excellent contributions. Let us express also our gratitude for the useful guidance which we received from Prof. K. Lambeck, A. Prof. A. Stolz and Dr. R. Coleman of the Scientific Advisory Committee and the continuous support given by Prof. E.W. Grafarend. Sincere thanks are due to the authors of the selected papers for agreeing to contribute to this Monograph, and for their positive cooperation during the production of this volume.

Description / Table of Contents: INTRODUCTION Evaporites may form in a spectrum of environments from continental sabkha (playa) to deep basins (see Kendall 1978 a, b, Schreiber 1978, 1986, Friedman and Krumbein 1985, for review). In the last two decades, many ancient evaporite basins have been interpreted using the sabkha model and the deep desiccated basin model, the former not excluding the latter. However, growing evidence has been gathered indicating that most evaporites are formed in subaqueous environments, so that it cannot be reasonably expected that one depositional model alone will explain the entire basin fill. The chapters in this volume discuss characteristic examples of evaporite basins, mostly of moderate size. Aspects of a saline giant, the Zechstein basin of Central and NW Europe, have been considered in Volume 10 of "Lecture Notes in Earth Sciences"...

Description / Table of Contents: PREFACE During the so-called Mid-Cretaceous interval, approximately 100 million years ago, the earth experienced a dynamic phase in its geologic history. Enhanced global tectonic activity resulted in a major rearrangment of the continental plates; accelerated spreading rates induced a first-order sea level highstand; intense off-ridge volcanism contributed to a modeled high atmospheric CO 2 rate; climatic conditions fluctuated; and major changes occurred in biologic evolutionary patterns. With the initiation of a gradual change from an equatorial, east-west directed current-circulation pattern to a regime, dominated by south-north and north-south directed current systems, the earth's internal clock was set for Cenozoic, "modern" times. The Mid-Cretaceous dynamic phase is recorded in a suite of sediments of remarkable similarity around the globe. Shallow-water carbonate platforms drowned on a global scale; widespread sediment-starved, glauconite and phosphate- rich sequences developed; and consequently, pelagic sedimentary regimes "invaded" shelf and epicontinental sea areas. This typical "deepening-upward" pattern is well-documented in Mid-Cretaceous sequences along the northern Tethys margin. Shallow-water carbonates are overlain by condensed glauconitic and phosphatic sediments, which, in turn, are blanketed by pelagic carbonates. In this volume, the example of the western Austrian helvetic Alps, built up of inner and outer shelf sediments deposited along the northern Tethys margin, is used to elucidate the paleoceanographic conditions, under which the Mid-Cretaceous triad of platform carbonates, condensed phosphatic and glauconitic sediments, and pelagic carbonates was formed. In the first part, the evolution of this sequence is traced from the demise of the platform (Aptian) to the return of detritus-dominated deposition (Upper Santonian). The second part includes a discussion of the reconstructed paleoceanographic and tectonic variables, their possible interaction, as well as their influence on sediment properties during this period. Special attention is paid to (1) subsidence behavior of the inner, platform-based shelf and the outer shelf beyond the platform, (2) ammonoid paleobiogeography, (3) the northern tethyan current system and its impact on sediment patterns, (4) the influence of an oxygen minimum zone, (5) sediment bypassing mechanisms on the inner shelf, (6) condensation processes, (7) phosphogenesis, (8) relative sea level changes, (9) genesis and the development of unconformities, (10) tectonic phases and their impact on sediment configuration, (11) drowning of the shallow-water carbonate platform, and (12) "asymmetric" sedimentary cycles. The detailed reconstruction of the development of sedimentary patterns both in time and space in this particular area, and its environmental interpretation, given in this volume, may serve as a contribution to a better understanding of the Mid-Cretaceous dynamic phase in earth's history...

Description / Table of Contents: This volume contains the contributions which have been presented at the 5. ALFRED WEGENER-Conference , held in Göttingen, Federal Republic of Germany, 21 - 24 May 1986. This conference was the first international meeting of the IGCP Project 216 :"global biological events in earth history". The aim of the conference was, to discuss (a) the state-of-the-art in respect to the recognition of bio-events and to the analysis of their causes (b) the presentation of new data (c) the strategies which are needed for further research, carried out in the international cooperation programme of Project 216. It was intended to achieve with these discussions a more critical approach to the problems of global bio-events.

Description / Table of Contents: PREFACE This volume presents results from members of the Project 216 "Global Biological Events in Earth History" of the International Geological Correlation Programme (IGCP). The project, initiated by the elder editor (O.H.W.) within the framework of the International Palaeontological Association (IPA) in the late 70s, was officially established in 1984. Subsequently, it led to the first three conferences on Global Bio-Events, and their respective symposia volumes: 1) In G6ttingen, West Germany in 1986 (WaUiser, O. H., Ed., 1986, Global Bio-Events, Springer-Verlag); in Bilbao, Spain in 1987 (Lamolda, M. A., Kauffrnan, E. G., and Walliser, O. H., Eds., 1988, Paleontology and Evolution: Extinction Events; Rev. Espafiola de Paleont., n. extraord.); and in Boulder, Colorado, U.S.A. in 1988 (this volume). The next meeting, on Innovations and Revolutions in the Biosphere, is planned in Oxford, England in 1990, to be hosted by Martin Brasier. During the history of this project, the focus of our research has shifted significantly. Initial focus was on specific global mass extinctions (e.g. the Precambrian/Cambrian, Frasnian/Fammenian, Cretaceous/Tertiary, and Eocene/Oligocene events) to a broader treatment of Phanerozoic mass extinctions, their differences or unifying factors, and their causal mechanisms. Subsequent meetings have attempted to focus attention on a fuller spectrum of global bio-events in Earth history. The Boulder Conference, and this volume, although still strongly influenced by the excitement of mass extinction research, expresses these new trends in bioevent studies. The Boulder conference, held on May 16-23, 1988, focused on a broad spectrum of Abrupt Changes in the Global Biota. Over 100 participants from 13 nations attended this meeting, representing diverse disciplines of palaeobiology, palaeoclimatology, palaeoceanography, sedimentology, geochemistry, and a broad spectrum of the stratigraphic and geological sciences. Four days of talks were supplemented by field trips to the continental Cretaceous/Tertiary boundary in the Raton Basin, New Mexico, and to the Cenomanian/Turonian mass extinction interval exposed near Pueblo, Colorado. The Conference itself was characterized by a great diversity of approaches to bio-event research, and the phenomenon of mass extinction. In particular, interactive causes involving both extraterrestrial and earthbound (tectonic, oceanographic, climatic) forces were discussed, and each major Phanerozoic mass extinction was treated by specialists in the field. In addition, many presentations focused on the causal mechanism and patterns of bio-event development that were not restricted to mass extinction intervals, but which could cause regional to global biotic response at any time in Earth history. Thus, both the conference, and this volume, focus attention on climatic and oceanic perturbations from anoxia, advection, rapid thermal change, toxic chemical enrichment, and energy shock from impacts and giant tsunamis as forcing mechanism for regional to global bio-events. The delicate balance of perched ocean/ctimate~fe systems under typical warm equable non-glacial Phanerozoic conditions, and their susceptibility to shock from even small perturbations, was a philosophical theme that ran throughout the meeting. The case for extraterrestrial forcing of tectonic, volcanic, and biological events was greatly strengthened by new data presented at this conference, with special concern for the effects of small comet/meteorite impacts in the oceans, and their chemical/physical/biological signature which might be used, in the absence of shocked minerals, microspheres or trace metals, to identify extraterrestrial events associated with global and regional bio-events. The conference benefitted from the introduction of much new data at high levels of resolution, especially from poorly studied mass extinction intervals. Interactive discussions, and many new ideas characterized the meeting. The new scientific results of this meeting are exciting; they are reviewed in the Conference Report published in Episodes (1988, v. 11, n. 4, p. 289-292). Most of the key papers presented at the Boulder meeting appear in this volume. What lies ahead in bio-event research? Clearly, a great deal of excitement and an age of discovery. We have only touched the surface of this new and dynamic field. We are starting to comprehend the dynamics of global mass extinctions, integrating detailed geochemical, physical and biological data into scenarios of cause and effect. But in the years ahead lies the job of understanding the whole spectrum of regional bioevents preserved in the ancient record, and especially the application of this research to solutions of the critical problems inherent in global change and the modern biotic crisis. Future directions for research at this conference include the investigation and modeling of abrupt chemical and thermal shifts in the ocean, the effects of impacts at deep ocean sites, the documentation of successful survival strategies and repopulation patterns following biotic crises, the deep ocean record of bio-events, and focus on alternative forces other than impacting to account for mass extinction events. This volume introduces some of these new pathways in bio-event research.

Description / Table of Contents: OPENING ADDRESS On behalf of the Local Organizing Committee, I welcome you all to the first International Workshop on GPS-techniques in surveying and geodesy held at this university. This workshop is designed to bring together experts from various countries and also scientists who carry out, analyze and interpret such measurements with those who work on instrumental and theoretical problems. The workshop focuses hereby on high-precision applications with emphasis on monitoring time-dependent phenomena such as those relevant to geodynamics as well as men-made constructions as those in civil engineering and similar fields. It is astonishing to see how, in spite of all earlier satellite work over the last two decades, GPS-methods became so fast a relevant new technology, in its proper sense, in modern geodesy and surveying besides VLBI and Satellite Laser Ranging (SLR). With the recent development of new dual-frequency receivers the role of GPS-procedures in monitoring large-scale phenomena over big distances will still expand; and the application of kinematical GPS-approaches is of utmost interest in solving high-precision problems. It is indeed fascinating to realize how GPS-methods have become in such a short time a surprisingly efficient and effective, this means : fast, precise and easy to apply, tool which is able to replace already now, after a few years of existence and with an incomplete set of a few out of the 18 satellites (of the final stage), at least partially some expensive, slow and cumbersome classical surveying methods. On the other hand, it cannot be overemphasized that GPS-procedures are still at their beginning and the full spectrum of their capabilities still has to be explored. In Europe, for example, where excellent classical surveying systems do exist the situation is quite different from the situation in other countries such as Canada or the USA. Even within Europe the application types of GPS-methods will vary; for example, in Norway the situation is quite different from central European countries. It is often forgotten, that together with GPS we will have to introduce new concepts and a new thinking in combination with other modern satellite procedures. GPS itself can resolve only a small part of the problems to be solved by modern geodesy but it will open the way to a great variety of new applications and capabilities. Modern global tectonics is just one of the new disciplines of high interest and great practical impact. I could continue in citing other similarly important new fields. GPS is, however, of special importance because it replaces old technologies and fills gaps where modern and efficient tools are most needed. Consequently, also the optimal combination of GPS-methods with new auxiliary and also classical high-precision techniques is of great importance, mainly under the european conditions outlined above. Moreover, the real-time or almost-real-time use of GPS in combination with photogrammetry, inertial geodesy, gravity gradiometry or even classical surveying is of substantial interest. It is indeed important to realize the new concepts in modern satellite and space methods and I, therefore, spoke above of a new "technology" which should be optimally developed as there is a worldwide need of such capabilities and tools. In view of the few active NAVSTAR-satellites in sky in 1988 this is perhaps not the best year for GPS-applications but the right time for a review of the experience gained until now and using it as a base for the planning of the future...

Description / Table of Contents: PREFACE Following the economical and social development of the local communities, mountain regions of temperate climates are increasingly becoming the site of valuable infrastructures and important urban and industrial settlements. As the catastrophic events of last years in the European Alps have clearly shown, the vulnerability of these territories has correspondingly increased, in terms of both property damage and losses of human life. Until recently, the hydraulic scientific community has paid little attention to mountain watersheds, except perhaps during the period if the hydropower development. Nevertheless attention was then focused on problems and methodologies somewhat different from the issues of actual environmental concern. More recently, however, hydraulic engineers have joined their colleagues from forest and rural engineering, who have traditionally dealt with erosion control in mountain areas, to bring in their own methodology, already experienced in lowland rivers. At the same time, academic people focused an interest in some phenomena, like massive transport, which is typical of mountain environment. To bring together all these contributions and to make the state of the art of the mountain river science (oropotamology) and technology, an International Workshop was called at the University of Trent (Italy), on October 1989, under the sponsorship of Fluvial Hydraulic Section of the IAHR. Three main topics have been recognized as particularly relevant from the point of view of both research and professivnal people: a) Hydrodynamics of steep channels and local scale process; b) Sediment movement and sediment training, with special emphasis on massive transport; c) Particular features of sediment transport related to non-uniform grain-size. However, as it is the case in these circumstances, the contest of several contributions often spread over more than one topic. In the following Introduction to papers, the three topics were split into 11 Sections, each one devoted to a more particular aspect recurrently addressed during the discussion. The same paper, thus, may be mentioned in different Sections of the Introduction.

Description / Table of Contents: INTRODUCTION Humic substances, comprise a class of biogenic, coloured, organic substances that are ubiquitous in soil, sediment and water. Originally, the occurrence and nature of humic substances were regarded as issues of primarily academic interest. This situation is now rapidly changing, and studies of humics have gained recognition as important contributions to environmental science. In particular it has been shown that humic substances, in several different ways can interact with biologically active substances, thereby modifying their environmental impact. Whereas the history of soil humus studies goes back to the 19th century, the awareness of aquatic humus is more recent. The brownish colour that, in many surface waters, shows the presence of substantial amounts of humic substances, was long considered to be a harmless phenomenon that did not call for detailed investigations. Hnmic waters had few known toxic effects, and the refractory character of hnmic substances indicated the they played a peripheral role in most biochemical processes. In fact, it was not until the mid 70's that aquatic humus was brought into focus in environmental science. The event trigging this was the discovery of the interaction between humic substances and chlorine used for disinfection of drinking water. Toxic substances, such as chloroform, were detected in all chlorinated waters, and humic substances were identified as the main precursors. The role of humics in the mobilization and subsequent transport of trace elements in the environment was recognized for the first time in the early 80's. This role was considered to be of particular importance in connection with geologic storage of high-level radioactive waste. In water with "normal" concentration levels of humic compounds, the speciation of e.g. the trivalent actinides, would be entirely dominated by the complexation with these agents. The topics of this conference (Session 1 - Isolation, fractionation and characterization; Session 2 - Biological and chemical transformation and degradation; Session 3 - Complex formation and interactions with solids; Session 4 - Biological activity; and session 5 Halogenation of humic substances) were selected to represent areas of current environmental interest...

Description / Table of Contents: The subject of the book is an indepth description of the theory and mathematical models behind the application of the Global Positioning System in geodesy and geodynamics. The text has been prepared by leading experts in the field, contributing their particular points of view. Unlike a collection of disjoint papers, the text provides a continous flow of ideas and developments. The mathematical models for GPS measurements are developed in the first half of the book, followed by the description of GPS solutions for geodetic applications on local, regional and global scales.

Description / Table of Contents: PREFACE The emergence of new information from drilling in deep-sea and coastal areas and the surfacing of the plate tectonics theory probably had the greatest impacts in recent decades on the highly accelerated growth of knowledge regarding the evolution of sediments and sedimentary rocks. Studies in recent years have also provided new insights on global sedimentary processes, and isotopic tools in many ways have enhanced our knowledge and have provided even an unexpected added dimension to the mechanisms of some specific processes. Many different uses of isotopic tools in studies of sedimentary processes can be found in the literature, but the information is highly scattered in the vast field of sedimentology. The disseminated state of existing isotopic knowledge on sedimentary systems has undoubtedly deprived many practitioners in the field to fully appreciate the benefits and limitations, and even the apparent confusion, concerning the use of isotopic tools. We have endeavored here to bring together discussions on some major sedimentary systems in the sedimentary cycle and to analyze them according to isotopic evidence. To accomplish such a task required contributions from many individuals. We were fortunate to have friends who accepted to share our goals. We most sincerely thank all the contributors to this book and deeply appreciate their patience and fortitude despite our undue demands on them to reach our objectives...

Description / Table of Contents: PREFACE The objective of this book is to introduce the practitioner as well as the more theoretically interested reader into the integration problem of spatial information for Geo-lnformation Syslems. Former Get-Information Systems are restricted to 2D space. They realize the integration of spatial information by a conversion of vector and raster representations. This, however. leads to conceptual difficulties because of the two totally different paradigms. Furthermore, the internal topology of the get-objects is not considered. In recent years the processing of 3D information has played a growing role in Get-Information Systems. For example, planning processes for environmental protection or city planning are dependent on 3D data. The integration of spatial reformation will become even more impoaant in the 3D context and with the development of a new generation of open GISs. This book is intended to respond to some of these requirements. It presents a model for the integration of spatial information for 3D Geo-lnformation Systems (3D-GISs). As a precondition for the integration of spatial information, the integration of different spatial representations is emphasized. The model is based on a three-level notion of space that likewise includes the geometry, metrics and the topology of get-objects. The so called extended complex (e-complex) is introduced as a kernel of the model. Its internal basic geometries are the point, the line, the triangle and the tetrahedron. It is shown how a convex e-complex (ce-complex) is generated by the construction of the convex hull and the "'filling" of lines, triangles and tetrahedra, respectively. As we know from computer geometry, this results in substantially simpler geometric algorithms. Additionally, the algorithms gain by the explicit utilization of the topology of the ce-complex. This book also builds a bridge from the GIS to the object-oriented database technology, which will likely become a key technology for the development of a new generation of open Geo-lnformation Systems. In the so-called GEtmodel kernel "building blocks" are introduced that s~mplify the development of software architectures for geo-applications. A geological application in the Lower Rhine Basin shows the practical use of the introduced geometric and topological representation for a 3D-GIS...

Description / Table of Contents: PREFACE Through the last few decades inversion concepts have become an integral past of experimental data interpretation in several branches of science. In numerous cases similar inversion-like techniques were developed independently in separate disciplines, sometimes based on different lines of reasoning, and sometimes not to the same level of sophistication. This fact was realized early in inversion history. In the seventies and eighties "generalized inversion" and "total inversion" became buzz words in Earth Science, and some even saw inversion as the panacea that would eventually raise all experimental science into a common optimal frame. It is true that a broad awareness of the generality of inversion methods is established by now. On the other hand, the volume of experimental data varies greatly among disciplines, as does the degree of nonlinearity and numerical load of forward calculations, the amount and accuracy of a priori information, and the criticality of correct error propagation analysis. Thus, some clear differences in terminology, philosophy and numerical implementation remain, some of them for good reasons, but some of them simply due to tradition and lack of interdisciplinary communication. In a sense the development of inversion methods could be viewed as an evolution process where it is important that "species" can arise and adapt through isolation, but where it is equally important that they compete and mate afterwards through interdisciplinary exchange of ideas. This book was actually initiated as a proceedings volume of the "Interdisciplinary Inversion Conference 1995", held at the University of Aarhus, Denmark. The aim of this conference was to further the competition and mating part of above-mentioned evolution process, and we decided to extend the effect through this publication of 35 selected contributions. The point of departure is a story about geophysics and astronomy, in which the classical methods of Backus and Gilbert from around 1970 have been picked up by helioseismology. Professor Douglas Gough, who is a pioneer in this field, is the right person to tell this success story of interdisciplinary exchange of research experience and techniques [1-31] (numbers refer to pages in this book). Practitioners of helioseismology like to stress the fact that the seismological coverage on the Sun in a sense is much more complete and accurate than it is on Earth. Indeed we witness vigorous developments in the Backus & Gilbert methods (termed MOLA/SOLA in the helioseismology literature) [32-59] driven by this fortunate data situation. Time may have come for geophysicists to look into helioseismology for new ideas. Seismic methods play a key role in the study of the Earth's lithosphere. The contributions in [79 - 130,139 - 150] relate to reflection seismic oil exploration, while methods for exploration of the whole crust and the underlying mantle axe presented in [131 - 138, 151 - 166]. Two contributions [167 - 185] present the application of inversion for the understanding of the origin of petroleum and the prediction of its migration in sedimentary basins. Inversion is applied to hydrogeophysical and environmental problems [186 - 222], where again developments are driven by the advent of new, mainly electromagnetic, experimental techniques. The role of inversion in electromagnetic investigations of the lithosphere/astenosphere system as well as the ionosphere axe exemplified in [223 - 238]. Geodesy has a fine tradition of sophisticated linear inversion of large, accurate sets of potential field data. This leads naturally to the fundamental study of continuous versus discrete inverse formulations found in [262-275]. Applications of inversion to geodetic satellite data are found in [239 - 261]. General mathematical and computational aspects are mainly found in [262 - 336]. Nonlinearity in weakly nonlinear problems may be coped with by careful modification of lineaxized methods [295 - 302]. Strongly nonlinear problems call for Monte Carlo methods, where the cooling scedule in simulated annealing [303 - 311,139 - 150] is critical for convergence to a useful (local) minimum, and the set of consistent models is explored through importance sampling [89 - 90]. The use of prior information, directly or indirectly, is a key issue in most contributions, ranging from Bayesian formulations based a priori covariances e.g. [98 - 112,122 - 130, 254 - 261], over more general but also less tractable prior probability densities [79 - 97], to inclusion of specific prior knowledge of shape [284 - 294, 312 - 319]. Given the differences and similarities in approach, can we benefit from exchange of ideas and experience? In practice ideas and experience seldom jump across discipline boundaries by themselves. Normally one must go and get them the hard way, for instance by reading and understanding papers from disciplines far from the home ground. Look at the journey into the interdisciplinary cross-field of inversion techniques as a demanding safari into an enormous hunting ground. This book is meant to provide a convenient starting point.

Description / Table of Contents: INTRODUCTION The awareness that mankind is able to influence and modify not only the local but also the global climate has led to a strongly growing interest in climate research. Strengthened research activities, which also made use of improved and novel experimental techniques, have yielded a wealth of information on climatic patterns in the past. At the same time, climate modelling has made much progress. While some questions have been answered, new problems have been recognized. One question related to anthropogenio climatic change is about the nature and causes of natural variations, against the background of which man-made changes must be viewed. The contributions to this volume all deal with the variabilitY of climate. Some papers are reviews of the knowledge to a current topic, others have more the character of an original contribution. The obseryational studies cover the range from year-to-year variations up to glacial-interglacial contrast, thereby going from instrumental data to results from proxy records...

Description / Table of Contents: PREFACE The search for tin dates back to the earliest days of civilization. For about 40 years, world tin mining has oscillated at a level of 150,000-250,000 t Sn/year, with a mine output in 1989 of 210,000 t Sn (MCS 1990). This figure corresponds to a current annual value of about US$1.5 billion and places tin ninth on the metal market behind iron, gold, uranium, copper, zinc, silver, platinum and nickel. Tin deposits belong to the granite-related ore deposit spectrum which includes many metals vital to current and future technologies such as Cu, W, Mo, U, Nb, Ta, Ag, Au, Sb, Bi, As, Pb, Zn, REE, Be, Ga and Li. The granitic rocks associated with tin and tin-tungsten deposits have long been identified as a special group of granites, the so-called tin granites. These rocks provide a unique opportunity to study the magmatic and hydrothermal history of tin ore formation. Tin granites are more easily identifiable as parent rocks for tin (and tungsten) mineralization than is the case for other mineralized granitic rocks such as molybdenum and copper porphyries. The magmatic molybdenum and copper distribution patterns are more complex (control by sulfide solubilities), and commonly obliterated by fluid interaction. The relatively simple situation of tin granites provides therefore an invaluable opportunity to study some metallogenic aspects of magmatic-hydrothermal ore deposits in general. The present study attempts to develop a general metallogenic model for tin in identifying the essential or relevant processes in tin ore formation. The methodological principle is based, on an interplay between a background of some basic petrogenetic concepts and a number of specific local and regional data on tin deposits and tin provinces, with particular reference to those areas with which the author is most familiar with (Bolivia, SE Asia, Europe). This inductive approach condenses the many apparently specific complexities encountered in individual ore deposits to a few major processes of general importance. The inherent reductionism may have a personal bias which is probably inevitable in any simple and broad-scale picture ("Apr6s tout, la raison est bien I'esclave des passions"; Feyerabend 1979:210). The critical problem of the relevance of those factors chosen for our model can be judged by its degree of consistency and predictive capability for new and analogous cases...

Description / Table of Contents: PREFACE This volume comprises the main lectures delivered at the Fourth International Summer School in the Mountains on "Mathematical and Numerical Techniques in Physical Geodesy", held from August 25 to September 5, 1986 in Admont, Austria. The School was organized by the Institute of Theoretical Geodesy of the Technical University Graz, Austria under the auspices of the International Association of Geodesy. All five continents were represented by 70 participants from over 20 countries. The purpose of the Summer School was to provide an introduction to advanced techniques which represent the mathematical vehicle for the treatment of modern geodetic problems, to familiarize participants with the present state of the art of global and local gravity field determination methods, ranging from orbit theory, the key satellite techniques, to inertial and standard terrestrial methods, and to discuss future scientific developments. The arrangement of this volume matches the sequence of lectures given at the School. The theoretical PART A represents the mathematical framework of modern physical geodesy, the application PART B deals with the key satellite and surface techniques, providing the detailed structure of the earth's gravity field. PART A: One of the main goals in physical geodesy, global and local gravity field determination, is pursued by extensively applying functional analytic methods. Recently special attention is being given to the base function and norm choice problem, and to the establishment of a sound link between density distributions inside the earth as the source and observed or estimated gravity field quantities as the effect. The lectures by C.C. Tscherning focus on this topic. Space and time dependent problems of discrete and continuous type are encountered in modern geodesy nowadays and dealt with in the lectures by F. Sans6. Estimation theory either in its stochastic or statistic formulation plays a key role in the processing of processes like the earth's gravity field. The consistent processing of large structured data sets calls for equally structured numerical algorithms. Spectral analysis with its powerful fast Fourier transform has become a common tool for the treatment of such problems. An introduction to spectral methods, supplemented by numerous examples, is provided by B. Hofmann-Wellenhof and H. Moritz. PART B: The theory of orbit dynamics, tailored to the near circular orbits of most geodetic satellites, is fundamental to modern geodetic satellite techniques and discussed in the lectures by O.L. Colombo. Particular emphasis is put on the interplay between orbit perturbations and the earth's disturbing gravity field and its mapping by satellite techniques like satellite altimetry, satellite-tosatellite tracking and satellite gradiometry. Satellite gradiometry, which is discussed in the lectures by R. Rummel in detail, with regard to the geometric structure of the gravitational field, the observability of the gradients, and the mathematical model underlying the gravity field recovery problem, promises to provide particularly detailed information about the gravity field of our planet. The global structure of the earth's gravity field is described in terms of earth gravity field models which are derived from both satellite and surface data. The many delicate, mathematically as well as numerically challenging problems, related to the consistent processing of very large space distributed data sets, and proposed solutions are presented in the lecture by R.H. Rapp. For many years various attempts have been made to explain the shorter wavelength part of the earth's anomalous gravity field by isostatic phenomena. Recently several high resolution topographicisostatic earth models have been computed based on global digital terrain data using different techniques fo~ the estimation of the parameters of the chosen isostatic model. A declared goal is the maximum smoothing of the observed gravity field by removing the contribution of the topography and its isostatic compensation. This topic is discussed in the lectures by H. SUnkel. Inertial methods are steadily gaining importance, power and application. This is not only due to hardware improvements in terms of precision and reliability, but also due to recent advances in the mathematical and numerical modelling of the system's performance. An investigation of the error characteristics of inertial survey systems and their interaction with the anomalous gravity field, studied in the framework of dynamic system analysis, is the topic of the lectures by K.-P. Schwarz and the key issue for further improvements and possible integrations with other positioning systems. Geodetic data have both geometric and physical ingredients of various nature. Standard geodetic processing procedures aim at a separation of geometry from physics. Integrated geodesy, in contrast, has been designed as a very sophisticated melting pot which handles practically all available geodetic data in a consistent and optimal way.lt handles surface and satellite data with either geometrically or gravity field dominated content, and geophysical data in terms of density and seismic informatlon just as well and represents as such the great synthesis of mathematical modelling in connexion with geodetic data processing techniques; these advanced ideas are presented in the lectures by G. Hein. This volume presents highlights of modern geodetic activity and takes the reader to the frontiers of current research. It is not a textbook on a closed and limited subject, but rather a reference book for graduates and scientists working in the vast and beautiful, demanding but rewarding field of earth science in general and physical geodesy in particular. The editor expresses his appreciation to all authors of this volume for their advice and help in formulating and designing the scientific program of the Summer School, for providing typewritten lecture notes, and for their excellent cooperation.

Description / Table of Contents: PREFACE The four-year period of activity of the Groupement de Recherche 942 (GDR) of the Centre National de la Recherche Scientifique (CNRS) came to an end in December 1993. This GDR was a scientific association grouping research teams from the academic sphere -- i.e. the Unités de Recherches Associées 723 & 724 of the CNRS as well as the Universities of Orléans and Paris-Sud -- and from the industrial world: Elf-Aquitaine Production, TOTAL and the Institut Français du Pétrole (IFP). The aim of the GDR was to understand the processes and the causes of organic carbon fossilization in sediments, especially when they can be modified by environmental conditions such as climate, eustatism, productivity etc., factors which can alko interact. This goal implies the simultaneous study of ancient geological formations (hydrocarbon source rocks from the famous Kimmeridge Clay Formation) and recent Quaternary sediments (the Lac du Bouchet or lake Bouchet maar, Massif Central, France). In the latter case, we benefit from a fine-scale stratigraphical framework as well as a reliable reconstruction of the local and regional environment. This volume is a collection of papers representing oral presentations given on December 7, 1993, at the Société Géologique de France in Paris, during the final meeting of the GDR. These articles thus report the latest developments of the studies carried out under the GDR. However, this is not the first publication of our results, which can be found in the papers referred to in each article. The Kimmeridge Clay Formation was previously studied in 1987, by the Yorkim Group from IFP, Elf-Aquitaine and the British Geological Survey, on the basis of a series of wells drilled across the Cleveland Basin of Yorkshire. In each well, the distribution with depth of the total organic content is cyclic. We have compared some of the organic cycles from two wells (Matron and Ebberston) based on mineralogy, organic and inorganic geochemistry and petrography, at a high resolution scale (centimetric). The main conclusion of this work is that the driving force for organic matter accumulation in the studied cycles was organic phytoplankton productivity. Oxygenation conditions seem to have played a secondary role as a positive feedback action enhancing organic matter storage. Lac du Bouchet is located on the Devès volcanic plateau, 15 km SW of Le Puy en Velay, at an altitude of 1205 m. The depth of the water column is 28 m. The lake has a subcircular shape (1 km in diameter) and a very restricted watershed. This site is exceptionally suitable for research on climate variations and palaeomagnetic field modifications (Euromaars EC Program). The GDR focused on sedimentary organic matter and its relationship to inorganic phases. An important result is that organic matter appears to be a good indicator of palaeoenvironmental reconstructions for over 350 000 years. In addition, the study of early diagenetic reactions in surficial sediments (porewater and solid phase) allows the specification of the processes of organic matter degradation and storage in such an oligothrophic lake.

Description / Table of Contents: PREFACE During the last decades, remarkable progress in heat flow studies has been made and a rough picture of the global surface heat flow density distribution can now be drawn. Simultaneously, the question of over which time period the surface heat flow is constant arose. There is a big field of model calculations, based on the changes in radioactive heat generation of the Earth, on plate motions, on stretching hypotheses or on other ideas, which result in geotherms in the geological past. Although these speculative paleogeotherms seem to be realistic especially in oceanic areas they do not belong to the scope of this book. In continental areas however, it is not possible to find a simple time dependence of the surface heat flow density. However, petroleum research and tectogenetic studies are very interested in the geothermal history of sedimentary basins and other continental areas. To obtain satisfactory results, a more or less direct determination of paleo heat flow density or geothermal gradient would be necessary to give more certain boundary conditions for calculating oil generation, and for controlling tectogenetic hypotheses. There are many methods available in the geosciences to determine temperatures in the geological past. Most of these models are able to estimate temperatures at which a mineral or a mineral assemblage was formed. These methods, however, are mostly unsuitable to reach the main goal of paleogeothermics in general, which is to determine the (regional) heat flow density variations during the geological past for bigger geological units, such as sedimentary basins. The methods applied most in sedimentary basins have been deduced from the degree of coalification of organic matter. Although much effort has been made to explain analytically the organic metamorphism, the results found up to now have been insufficient . However, the widespread application of this thermometer to estimate ancient thermal conditions is also reflected in the contents of this very volume where the interpretation of the degree of coalification of organic matter plays an important role. As well as this geothermometers, other methods are reviewed from a geophysical viewpoint which favours methods suitable to determine a paleothermal state of the upper crust. Further contributions of this book deal with - the history of the earth's surface temperature whose change provides an essential correction factor in heat flow density determinations, - isotope geothermometers and their application to various environments to evaluate thermal conditions in the past geological history, - an application of the radiometric dating method to retrace the paleothermal condition of the Central Alps. Most of the contributions were presented at the symposium "Paleogeothermics" which was held at the 18. General Assembly of the International Union of Geodesy and Geophysics, August 15-27, 1983 in Hamburg/FRG. It has been the first time that such a symposium has been organized by the International Heat Flow Commission, and this book presents an attempt to define paleogeothermics under the auspices of the International Heat Flow Commission.

Description / Table of Contents: INTRODUCTION Theoretical modelling and the use of mathematical methods are presently gaining in importance since progress in both geology and mathematics offers new possibilities to combine both fields. Most geological problems are inherently geometrical and morphological, and, therefore, amenable to a classification of forms from a "Gestalt point of view". Geometrical objects have to possess an inherent stability in order to preserve their essential quality under slight deformations. Otherwise, we could hardly conceive of them or describe them, and today's observation would not reproduce yesterday's result (DANGELMAYR & GÜTTINGER, 1982). This principle has become known as "structural stability" (THOM, 1975), i.e. the persistence of a phenomenon under all allowed perturbations. Stability is also, of course, an assumption of classical Newtonian physics, which is essentially the theory of various kinds of smooth behavior (POSTON &STEWART, 1978). However, things sometimes "jump". A new species with a different morphology appears suddenly in the paleontological record (EI.DREDGE & GOULD, 1972), a fault develops, a landslide moves, a computer program becomes unstable with a certain data configuration, etc. It is, surprisingly, the topological approach which permits the study of a broad range of such phenomena in a coherent manner (POSTON & STEWART, 1978; LU, 1976; STEWART, 1982). The universal singularities and bifurcation processes derived from the concept of structural stabiIity determine the spontaneous formation of qualitatively similar spatio-temporal structures in systems of various geneses exhibiting critical behavior (DANGELMAYR & GÜTTINGER, 1982; THOM, 1975; POSTON & STEWART, 1978; GÜTTINGER & EIKEMEIER, t979; STEWART, 1981). In addition, this return to a "geometrization of phenomena"-- after decades of algorithmization-- comes much closer to the geologist's intuitive geometric reasoning. It is the aim of this study to elucidate, by examples, how the qualitative geometrical approach allows one to classify forms and to control the behavior of complex computer algorithms...

Description / Table of Contents: PREFACE It was only during the last few years, that the geological effects of storms and hurricanes in shallow-marine environments have been better appreciated. Not only were storm deposits recognized to dominate many shelf sequences, they also proved to be valuable tools in facies and paleogeographical analysis. Additionally, storm layers form important hydrocarbon reservoirs. Storm-generated sequences are now reasonably mell documented in terms of their facies associations in the stratigraphic record. Much less is known, however, about the effects and the depositional processes of modern storms, and about the styles of storm sedimentation on basinwide scales. Accordingly, the goal of this study is two-fold: 1. it presents two case studies of modern carbonate and terrigenous clastics storm sedimentatioq. The models derived from these actualistic examples can be used to interprete possible ancient analogues. 2. it presents a comprehensive analysis of an ancient storm depositional system (Muschelkalk) on a basin-wide scale. The underlying approach of this study is a process-oriented analysis of sedimentary sequences, an approach that ~as summarized by Matthews (1974, 1984) as "dynamic stratigraphy". The integration of actualistic models with a "dynamic" stratigraphic analysis helps to understand the dynamics of storm depositional systems; these models have a potential to be applied to other basins and to predict the facies organisation and the facies evolution in such systems...

Description / Table of Contents: PREFACE It is to-day generally recognized by environmental scientists that the particular behaviour of trace metals in the environment is determined by their specific physico-chemical forms rather than by their total concentration. With the introduction, several years ago, of atomic absorption spectrometry at many laboratories involved in environmental studies, a technique for simple, rapid and cheap determination of total metal concentrations in environmental samples became available. As a consequence, there is a plethora of scientific papers and reports where metal concentrations in the environment are only reported as total concentrations. It appears that the simplicity of making accurate determinations of total metal contents in water, sediment and biological samples has somewhat masked the need for improved knowledge about the various forms of metals occurring in the environment as well as the bioavailahility of these forms. In other words, the need for metal speciation in studies of metals in the environment does not seem to have become obvious to most environmental scientists until relatively recently. As a matter of fact, it was only in the middle of the 1970s that the first systematic attempts were made to obtain information about the various metal species occurring in environmental samples. During the last ten years, however, a revolutionary change of attitude towards the importance of metal speciation has occurred and considerable research effort has been devoted by environmental scientists to measuring the concentrations of biologically important trace metals in surface waters. There is currently an increasing effort to couple the development of chemical analytical techniques to process-related biological problems. Concurrently, a new focus is being imposed on ecological impact studies, that of determining which active trace metal species merit the most intensive research from the standpoint of environmental perturbation. Current efforts are directed towards the development of chemical speciation schemes which can be related directly to measures of bioavailability...

Description / Table of Contents: INTRODUCTION "The geological history, as expressed by the stratigraphic column, is basically composed of cycles of sedimentation, stratification and magmatism which correlate with relative changes in sea level determined in turn by different types of crustal movements. The classical sequence of stages "transgression - inundation - differentiation - regression - emergence" is believed to reflect the deformation phases of a geotectonic cycle" (Wezel,1988: p.37). The concept of geotectonic cycle is fundamental in geology because it links tectonics with sedimentary processes. According to Wezel (1988) the geotectonic cycle is an expression of cyclic variations in the behavior of the crust; more precisely,it is a geodynamic response to the Earth's variations in the rate of rotation (Mörner,19869 Whyte,1977~ Carey,1976).Based on a global analysis of geotectonic data, synchronous episodes of intense global swelling, governed by cyclically ordered diastrophic processes, were identified (Wezel,1985;1988). The process leading to these swells was termed krikogenesis (Wezel, 1988).It basically consists of not steady, localized, migratory vertical movements linked to mantle diapirism and concentrated in single zones.The overlying crust adjusts itself to mantle motions induced by krikogenesis, with the formation of transient troughs and swells ('touche-de-piano' tectonics).This mechanism was individuated in several areas (Wezel,1988). The history of the Earth is described by six episodes that repeat in the same way in the course of geological time.Their duration progressively decreases:the first cycle has a duration of about 200 million years, the following,younger cycles lasted 150, 115, 65, A5 and 20 m.y. ...

Description / Table of Contents: PREFACE The suggestion to compile and publish this volume dealing with some geoscientific problems of the Central Andes came up during a conference on "Mobility of Active Continental Margins" held in Berlin, February 1986. At this international conference, organized by the Berlin Research Group "Mobility of Active Continental Margins", colleagues from Europe, Southern and Northern America reported on their current investigations in the Central Andes. The Central Andes claim a special position in the 7000 km long Andean mountain range. In Northern Chile, Southern Bolivia and Northwest Argentina the Central Andes show their largest width with more than 650 km and along a Geotraverse between the Pacific coast and the Chaco all typical Andean morphotectonic units are well developed. Here, the pre-Andean evolution is documented by outcropping of Paleozoic and pre-Cambrian rocks. The characteristic phenomena of the Andean cycle can be studied along the entire geotraverse. The migration of the tectonic and magmatic activity starting in Jurassic and being active t i l l Quaternary is clearly evidenced. Besides the Himalaya, the Central Andes show with 70-80 km and -400 mgal the largest crustal thickness known in mountain ranges. These and many other interesting and exciting geoscientific features encouraged a group of geoscientists from both West-Berlin universities (Freie UniversitAt and Technische UniversitAt) to focus their studies along a geotraverse through the Central Andes. The realization of these studies would not have been possible without the active assistance and close cooperation of our colleagues from the geoscientific institutions in Salta (Argentina), La Paz and Santa Cruz (Bolivia) and Antofagasta and Santiago (Chile). Concerning the German participation, this joint and interdisciplinary project is financially supported since 1982 as Reserach Group" Mobility of Active Continental Margins" by the German Research Society and by the West-Berlin universities as well. A number of colleagues from universities in West Germany take part in this project, too. The papers presented here deal with the period from Late Precambrian up to the youngest phenomena in Quaternary. The contributions cover the whole spectrum of geoscientific research, geology, paleontology, petrology, geochemistry, geophysics and geomorphology. In conclusion, the data published here may help to improve the picture of Andean structure and evolution. The detailed investigations carried out in the past years show, that the first simple plate tectonic models proposed in the beginning of the seventies have to improved and modified. Furthermore, the results can be seen as contribution to the international Lithospheric Project and as a useful data base for the construction of a Central Andean Transect...

Description / Table of Contents: INTRODUCTION The study is essentially empirical, since it portrays and appraises two different water management systems, and relates them to one another. Yet the analysis has also been made with definite research aims in mind. Its focus has been narrowed down to the environmental assessment of urban water management systems in arid and semi-arid regions, especially with an eye to deal with information problems in the Developing World. The study addresses a set of very critical issues of global concern, and, thus, delineates a crucial topic for international research. The fact that a wide range of critical issues usually complicates and aggravates the given problem setting provides the comparative analysis with a special practical incentive to explore the opportunities for joint strategies and comprehensive solutions. However, the complexities involved between water management and the environment and the relative lack of a joint theory in that field pose certain difficulties to such an undertaking. In order to fully appreciate the underlying purpose of the study and the scope of its implications, the various facets of the problem setting and the essential ingredients of the general line of approach have first to be unravelled and expounded at some length. Above all, it needs to be shown how these facets combine to produce the complex, burning issues which in turn seem to, both in theory and practice, require correspondingly intricate, strategic approaches for their solutions...

Description / Table of Contents: PREFACE Seismic imaging is the process through which seismograms recorded on the Earth's surface are mapped into representations of its interior properties. Imaging methods are nowadays applied to a broad range of seismic observations: from nearsurface environmental studies, to oil and gas exploration, even to long-period earthquake seismology. The characteristic length scales of the features imaged by these techniques range over many orders of magnitude. Yet there is a common body of physical theory and mathematical techniques which underlies all these methods. The focus of this book is the imaging of reflection seismic data from controlled sources. At the frequencies typical of such experiments, the Earth is, to a first approximation, a vertically stratified medium. These stratifications have resulted from the slow, constant deposition of sediments, sands, ash, and so on. Due to compaction, erosion, change of sea level, and many other factors, the geologic, and hence elastic, character of these layers varies with depth and age. One has only to look at an exposed sedimentary cross section to be impressed by the fact that these changes can occur over such short distances that the properties themselves are effectively discontinuous relative to the seismic wavelength. These layers can vary in thickness from less than a meter to many hundreds of meters. As a result, when the Earth's surface is excited with some source of seismic energy and the response recorded on seismometers, we will see a complicated zoo of elastic wave types: reflections from the discontinuities in material properties, multiple reflections within the layers, guided waves, interface waves which propagate along the boundary between two different layers, surface waves which are exponentially attenuated with depth, waves which are refracted by continuous changes in material properties, and others. The character of these seismic waves allows seismologists to make inferences about the nature of the subsurface geology. Because of tectonic and other dynamic forces at work in the Earth, this first-order view of the subsurface geology as a layer cake must often be modified to take into account bent and fractured strata. Extreme deformations can occur in processes such as mountain building. Under the influence of great heat and stress, some rocks exhibit a taffy-like consistency and can be bent into exotic shapes without breaking, while others become severely fractured. In marine environments, less dense salt can be overlain by more dense sediments; as the salt rises under its own buoyancy, it pushes the overburden out of the way, severely deforming originally flat layers. Further, even on the relatively localized scale of exploration seismology, there may be significant lateral variations in material properties. For example, if we look at the sediments carried downstream by a river, it isclear that lighter particles will be carried further, while bigger ones will be deposited first; flows near the center of the channel will be faster than the flow on the verge. This gives rise to significant variation is the density and porosity of a given sedimentary formation as a function of just how the sediments were deposited. Taking all these effects into account, seismic waves propagating in the Earth will be refracted, reflected and diffracted. In order to be able to image the Earth, to see through the complicated distorting lens that its heterogeneous subsurface presents to us, in other words, to be able to solve the inverse scattering problem, we need to be able to undo all of these wave propagation effects. In a nutshell, that is the goal of imaging: to transform a suite of seismograms recorded at the surface of the Earth into a depth section, i.e., a spatial image of some property of the Earth (usually wave speed or impedance). There are two main types of spatial variations of the Earth's properties. There are the smooth changes (smooth meaning possessing spatial wavelengths which are long compared to seismic wavelengths) associated with processes such as compaction. These gradual variations cause ray paths to be gently turned or refracted. On the other hand, there are the sharp changes (short spatial wavelength), mostly in the vertical direction, which we associate with changes in lithology and, to a lesser extent, fracturing. These short wavelength features give rise to the reflections and diffractions we see on seismic sections. If the Earth were only smoothly varying, with no discontinuities, then we would not see any events at all in exploration seismology because the distances between the sources and receivers are not often large enough for rays to turn upward and be recorded. This means that to first order, reflection seismology is sensitive primarily to the short spatial wavelength features in the velocity model. We usually assume that we know the smoothly varying part of the velocity model (somehow) and use an imaging algorithm to find the discontinuities. The earliest forms of imaging involved moving, literally migrating, events around seismic time sections by manual or mechanical means. Later, these manual migration methods were replaced by computer-oriented methods which took into account, to varying degrees, the physics of wave propagation and scattering. It is now apparent that all accurate imaging methods can be viewed essentially as linearized inversions of the wave equation, whether in terms of Fourier integral operators or direct gradient-based optimization of a waveform misfit function. The implicit caveat hanging on the word "essentially" in the last sentence is this: people in the exploration community who practice migration are usually not able to obtain or preserve the true amplitudes of the data. As a result, attempts to interpret subtle changes in reflector strength, as opposed to reflector position, usually run afoul of one or more approximations made in the sequence of processing steps that makes up a migration (trace equalization, gaining, deconvolution, etc.) On the other hand, if we had true amplitude data, that is, if the samples recorded on the seismogram really were proportional to the velocity of the piece of Earth to which the geophone were attached, then we could make quantitative statements about how spatial variations in reflector strength are related to changes in geological properties. The distinction here is the distinction between imaging reflectors, on the one hand, and doing a true inverse problem for the subsurface properties on the other. Until quite recently the exploration community was exclusively concerned with the former, and today the word "migration" almost always refers to the imaging problem. The more sophisticated view of imaging as an inverse problem is gradually making its way into the production software of oil and gas exploration companies, since careful treatment of amplitudes is often crucial in making decisions on subtle lithologic plays (amplitude versus offset or AVO) and in resolving the chaotic wave propagation effects of complex structures. When studying migration methods, the student is faced with a bewildering assortment of algorithms, based upon diverse physical approximations. What sort of velocity model can be used: constant wave speed v? v(x), v(x, z), v(x, y, z)? Gentle dips? Steep dips? Shall we attempt to use turning or refracted rays? Take into account mode converted arrivals? 2D (two dimensions)? 3D? Prestack? Poststack? If poststack, how does one effect one-way wave propagation, given that stacking attenuates multiple reflections? What domain shall we use? Time-space? Time-wave number? Frequency-space? Frequency-wave number? Do we want to image the entire dataset or just some part of it? Are we just trying to refine a crude velocity model or are we attempting to resolve an important feature with high resolution? It is possible to imagine imaging algorithms that would work under the most demanding of these assumptions, but they would be highly inefficient when one of the simpler physical models pertains. And since all of these situations arise at one time or another, it is necessary to look at a variety of migration algorithms in daily use. Given the hundreds of papers that have been published in the past 15 years, to do a reasonably comprehensive job of presenting all the different imaging algorithms would require a book many times the length of this one. This was not my goal in any case. I have tried to emphasize the fundamental physical and mathematical ideas of imaging rather than the details of particular applications. I hope that rather than appearing as a disparate bag of tricks, seismic imaging will be seen as a coherent body of knowledge, much as optics is...