work on structural and stratigraphic relationships is presented from various parts of the mountain belt. In the first paper of the section, R. O. Greiling (Heidelberg) describes the Middle Allochthon of Vasterbotten, northern Sweden, where tectonic windows through the Upper Allochthon (Seve Nappe) show that the Middle Allochthon has a similar lithostratigraphy to that of the Stalon Nappe Complex of the eastern Caledonian margin but with a more ductile deformation and metamorphosed to a higher grade following thrust emplacement. These relations are explained by suggesting that the window rocks were initially subducted beneath a colliding western plate but were later accreted to the base of the western plate and thrust with it. The thrust geometry of the windows, described as antiformal stacks, agrees with this model. The Middle Allochthon of the Caledonian margin in northern Sweden is described by R. O. Greiling and R. Kumpulainen (Heidelberg and Stockholm) who record two distinct metasedimentary units separated by a thick zone of mylonites interpreted as a lateral thrust ramp. Turbidites in the northern unit were derived from an unidentified igneous source to the east and cannot be correlated with other sequences in the Middle Allochthon. In another paper dealing with the northern Swedish Caledonides, L. Hansen (Uppsala) describes down-to-the-west normal faults cutting the autochthonous Cambrian sediments in the tunnel sections of the Vietas Hydropower Station, but themselves being truncated by the basal decollement of the Lower Allochthon.

The first North Sea Oil and Gas Reservoirs Conference was held in Trondheim in 1985 as part of the Norwegian Institute of Technology's 75th anniversary celebrations. Favourable reactions from the delegates prompted the Committee to re-run the event some three and a half years later, and it is now intended that the Confe rence be held on a regular basis as long as there is a demand for this type of gathering. The objectives of the 1989 Conference, which were broadly similar to those of the previous one, were: (a) to bring together those engaged in various geoscientific and reservoir engineering aspects of North Sea Oil and gas reservoirs in one forum; (b) to demonstrate wherever poSsible the interdependence of the various disciplines and specializations; (c) to promote innovative, synergistic approaches to research and development programmes aimed at North Sea conditions; and (d) to reflect current trends in the reservoir sciences. Naturally there was no place for specialist parallel sessions in a Conference aimed at encouraging interdisciplinary integration and awareness."

This book has been prepared by the collaborative effort of two somewhat separate technical groups: the researchers at the Institute for Petroleum and Organic Geochemistry, Forschungszentrum Jii lich (KFA), and the technical staff of Integrated Exploration Systems (IES). One of us, Donald R. Baker, from Rice University, Houston, has spent so much time at KFA as a guest scientist and researcher that it is most appropriate for him to contribute to the book. During its more than 20-year history the KFA group has made numerous and significant contributions to the understanding of petroleum evolution. The KFA researchers have emphasized both the field and laboratory approaches to such important problems as source rock recognition and evaluation, oil and gas generation, maturation of organic matter, expulsion and migration of hydrocarbons, and crude oil composition and alteration. IES Jiilich has been a leader in the development and application of numerical simulation (basin modeling) procedures. The cooperation between the two groups has resulted in a very fruitful synergy effect both in the development of modeling software and in its application. The purpose of the present volume developed out of the 1994 publication by the American Association of Petroleum Geologists of a collection of individually authored papers entitled The Petroleum System - From Source to Trap, edited by L. B. Magoon and W. G. Dow."

Sudbury, Ontario is one of the world's most polluted areas. A century of industrial activities has resulted in thousands of acidified lakes and vast areas of denuded land. This book describes, in a manner accessible to a wide audience, the damage and the efforts at environmental restoration at Sudbury which resulted in its winning a United Nations award in 1992 for land reclamation.
The book has been written by a distinguished group of contributors, ranging from experts in acid rain and land reclamation to environmental engineers and toxicologists.

About four years ago Dr. Gilbert White visited China and sowed the seeds of this project through conversations with Drs. Huang and Gong of the Chinese Academy of Sciences, and Mr. Long of the Yellow River Conservancy Commission. After some additional rounds of communications by letter, the plan for a workshop evolved and Drs. Wolman and Brush visited with Dr. Sabadell of the Nat_ional Science Foundation to begin the initial planning. In March 1987 Dr. Brush visited China and the details were worked out for the October 1987 workshop. At the outset it was recognized that the 10 American scientists and engineers ltad very Ii ttle knowledge of the Yellow River and none had ever seen it. Therefore, it became important that field trips be scheduled before the workshop to better set the stage for fruitful discussions. It was also acknowledged that the American participants could not present papers about the Yellow River per se so their offerings reflected their general knowledge of rivers using other rivers as examples. On the other hand the Chinese participants were all well into the difficult problems of harnessing the Yellow River and made their presentations accordingly. Despite these differences the subject matter was the unifying thread and cross communication was excellent.

Agricultural soils are subjected to many applied mechanical stresses that influence their behavior. Stresses arise from tillage machines, seeders and chemicals applicators, tractors, and equipment for harvest and transport. Applied stresses may compact or loosen the bulk soil. Micro sections of soil (aggregates or clods) may be compacted during tillage while the bulk soil is loosened. Because most granular soils are combined into structural units of varying sizes with different strengths and properties, prediction of the effect of stresses on the behavior of bulk soils is difficult. The basic strength properties of soil are determined by many fac tors: the size distribution of particles, chemical and mineralogical properties of inorganic clay fraction, the organic matter content and composition, the water content and the stress history. These factors combine and interact to produce many possible behavior patterns. Changes in structure of the soil from applied stresses and biologi cal reactions may profoundly influence storage and transmission of water, heat, and air, and the mechanical resistance to penetration by plant roots. They may also affect the traction of vehicles. Manipulation of structural properties of soils by tillage implements is a major cost under most crop production systems. Reduced energy use is also a significant conservation objective. Improved management systems are very dependent upon a better understanding of soils' response to applied stresses. The content of this book resulted from a NATO Advanced Research Workshop held in St. Paul, Minnesota, U.S.A. September 13-16, 1988."

PH. BOURDEAU Directorate-General Science. Research and Development. Commission of the European Communities. Brussels. Belgium We are living on a unique planet, the only one in the solar system where life exists. The very existence of life has modified the physical and chemical environment of the earth, its atmosphere and oceans, in a way that makes life sustainable. This system with its complex cybernetic mechanisms has been named GAIA by Lovelock. Man has always interfered with it on a more or less limited scale. This interference is now reaching global proportions such as climate modifications resulting from CO and trace gas 2 accumulation in the atmosphere or the destruction of stratospheric ozone, not to speak of global radioactive contamination. GAIA will probably prevail as a living system but it probably does not give much importance to man's survival as such, and it is man that has to take care of his own survival. In the ecosystem of Planet Earth, soils are the thin interface between lithosphere and atmosphere which constitutes the essential substrate for the terrestrial biosphere, the productivity of which far exceeds that of the oceans, even though the latter cover a much larger area than the continents. Soils themselves are complex systems. They develop through weathering of minerals, are colonised by living organisms which in turn modify their substrate making it suitable for other organisms. This induces a primary ecological succession which eventually reaches a climax, in equilibrium between climate, soil and the biological communities.

Nitrogen turnover in the soil-crop system; comparison of fourteen simulation models.- NQuantitative aspects of nitrogen nutrition in crops.- Modelling of the nitrogen cycle in farm land areas.- Nitrate leaching and soil moisture prediction with the LEACHM model.- Nitrate leaching and soil moisture prediction with the LEACHM model.- Some results of nitrogen simulations with the model ANIMO.- The distribution of water and nitrogen in the soil-crop system: a simulation study with validation from a winter wheat field trial.- Modelling water flow, nitrogen transport and root uptake including physical non-equilibrium and optimization of the root water potential.- Modelling water flow, nitrogen transport and root uptake including physical non-equilibrium and optimization of the root water potential.- Simulation of nitrogen dynamics and biomass production in winter wheat using the Danish simulation model DAISY.- Simulation of the nitrogen balance in the soil and a winter wheat crop.- Modelling nitrogen dynamics in a plant-soil system with a simple model for advisory purposes.- Simulation of nitrogen in soil and winter wheat crops: modelling nitrogen turnover through organic matter.- Simulation of nitrogen in soil and winter wheat crops: modelling nitrogen turnover through organic matter.- Simulation of nitrogen in soil and winter wheat crops: a management model that makes the best use of limited information.- Modelling water flow, nitrogen uptake and production for wheat.- WHNSIM - a soil nitrogen simulation model for Southern Germany.- A comparison of the performance of N simulation models in the prediction of Nmin on farmers' fields in the spring.- Response of wheat to nitrogen fertilization, a data set to validate simulation models for nitrogen dynamics in crop and soil.- List of participants.

"Reviews of Environmental Contamination and Toxicology" contains timely review articles concerned with all aspects of chemical contaminants (including pesticides) in the total environment, including toxicological considerations and consequences. It attempts to provide concise, critical reviews of advances, philosophy, and significant areas of accomplished or needed endeavor in the total field of residues of these and other foreign chemicals in any segment of the environment, as well as toxicological implications.

Soil is formed from the physical and chemical weathering of rocks-processes described historically becau'se they involve eons of time-by glaciation and by wind and water transport of soil materials, which are later deposited in deltas and loessial planes. Soil undergoes further transformations over time and provides a habitat for biological life and a base for the development of civilizations. Soil is dynamic-always changing as a result of the forces of nature and particularly by the influences of man. Soil has been studied as long as history has been documented. Numerous references to soil are found in historical writings such as Aristotle (384-322 Be), Theophrastus (372-286 Be), Cato the E1der (234-149 Be), and Varro (116-27 Be). Some of the earliest historical references have to do with the erosional forces of wind and water. The study of soils today has taken on increased importance because a rapidly expanding population is placing demands never before experienced on the soil. This has led to an increase in land degradation. Land degradation is one of the most severe problems facing mankind. Volume 11 of Advances in Soil Science was devoted entirely to this critical area of soil science. This series, Advances in Soil Science, was established to provide a forum for leading scientists to analyze and summarize the available scientific information on a subject, assessing its importance and identifying additional research needs.

The use of organic residues as a means of maintaining and increasing soil fertility is of long-standing. This tradition has been somewhat neglected since the introduc tion of mineral fertilizers at low cost. More and more farmers and scientists are now showing renewed interest in the proper and effective use of org~tnic residues, composts and other recycled organic additives. The role and function of organic amendments in modern agricultural systems have become topics of major interest in the scientific and agricultural communities. Research work on residue disposal has provided new concepts on the interaction between organic components and soils as well as new handling technologies (e. g. pelletizing of organic residues). The trend to conserve energy has led scientists to study the minimal tillage system, to find ways of replacing conventional inorganic fertilizers with natural organic prod ucts or microbial preparations, and to develop new composting methods. The drive to achieve higher yields in commercial greenhouse farming has led to a search for optimum substrates as growth media and for improved management techniques. This has led to the introduction of organic substitutes for peat, nota bly those originating from agricultural wastes. Another important aspect is the current interest in organic farming, where use of synthetic chemicals is avoided or prohibited. An increasing percentage of the population in highly developed countries is willing to pay premium prices for food produced on soils where inorganic fertilizers and other agricultural chemicals have not been used.

The collection of papers in this volume is a direct result of the Society of Economic Paleontologists and Mineralogists Research Symposium on "Thermal History of Sedimentary Basins: Methods and Case Histories" held as part of the American Association of Petroleum Geologists Annual Convention in New Orleans in March 1985. The original goal of the sym posium was to provide a forum where specialists from a variety of dis ciplines could present their views of methods that can be used to study the thermal history of a sedimentary basin or an important portion of a basin. An explicit part of that goal was to illustrate each method by presentation of a case history application. The original goal is addressed by the chapters in this volume, each of which emphasizes a somewhat different approach and gives field data in one way or another to illustrate the practical useful ness ofthe method. The significance of our relative ignorance of the thermal conductivities of sedimentary rocks, especially shales, in efforts to understand or model sedimentary basin thermal histories and maturation levels is a major thrust of the chapter by Blackwell and Steele. Creaney focuses on variations in kerogen composition in source rocks of different depositional environments and the degree to which these chem- . ically distinct kerogens respond differently to progressive burial heating."

***e FACHGEBIET*** Mathematical Geology, Computer Applications, Artificial Intelligence, Urban Economics and Regional Economics ***INTERESSENTENGRUPPE*** Of interest to Urban and Regional planners, civil engineers, geographers; computer scientists; operations researchers; landscape architects; and advanced students in the above disciplines.- Level: Technical Book, Monograph ***URHEBER*** T.J. Kim, University of Illinois, Champaign, IL; L.L. Wiggins, Massachusetts Institute of Technology, Cambridge, MA; J.R. Wright, Purdue University, Lafayette, IN (Eds.) ***TITEL*** Expert Systems: Applications to Urban Planning ***BIBLIOGRAPHISCHE-ANGABEN*** 1990. XIV, 268 pp. 48 figs. Hardcover DM 78, - ISBN 3-540-97171-8 ***LANGTEXT*** While expert systems have become a popular topic in the computing, medical and engineering fields, the expert system is still a new technology in urban planning. This book introduces expert systems for problem solving in urban planning and describes the way in which heuristic knowledge and rules of thumb of expert planners can be represented through computer programs. The book presents practical applications of expert systems for solving many important urban planning problems, particularly those issues that many practicing planners face in their daily operations. Problems and issues discussed are grouped in the following categories: - Land Use Planning - Transportation Planning - Site Selection and Analysis - Environmental Planning - Conflict Mediation and Legal Disputes - Future Developments and Directions Expert Systems: Applications to Urban Planning will benefit both urban planners who wish to learn how this new technology might be applied to their daily work as well as researchers in expert systems seeking new ideas for systems design.

The West African Sahel is the transition zone between the Saharadesert in the north of Africa and the more humid Sudanian zones in the south. Although diverse in many ways, the Sahelian countries have the common problem of a fragile agricultural sector. This predicament is mainly caused by low inherent soil fertility, limited and unpredictable rainfall, frequent droughts, and wind erosion that accelerates soil degradation and desertification, compounded by To assure food production in the future, means rapidly growing populations. of declining soil fertility and increasing must be found to offset the trends soil degradation through wind erosion. This is a challenge for agricultural research. Since 1985, the Special Research Program 308 'Adapted Farming in West Africa' at the UniversityofHohenheimin collaboration with the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) in Niger, has pursued the developmentof agricultural innovations for smallholder farmers in one of the most ecologically fragile regions of the world. The prevention of soil degradation, the restoration and maintenance of soil fertility, and the increase of land and labor productivity are key objectives of this multidisci plinary research program. From the beginning, a major focus of research has been wind erosion.

Biotechnology for Waste Management and Site Restoration covers: waste management - solid, gaseous, liquid; site restoration - radioactivity, organics, toxic metals; educational, economic, social and business aspects; and international collaboration. International collaboration is growing apace and many concrete projects have been started. The body of knowledge is growing. Over the long term, it is envisaged that this international collaboration will result in a long-term scientific and technological strategy, new technologies and alternative solutions, and practical implementations of biotechnology for the nuclear and industrial sectors of the economy.

As we enter the last decades of the twentieth century, many persistent and perplexing problems continue to afflict humankind. Thus it is appropriate to address, in a new group of books, two of the monumental issues that haunt people throughout the world. Soils and the Environment by Professor Gerald W. Olson is the first book in this new publish ing program on Environment, Energy, and Society. The purpose of all these books will be to explore the many interrelated facets of these topics and to provide guidance for dealing with problems and offering ideas for their solutions. Environment and energy are twin problems that occupy what many believe to be opposite sides of a two-headed coin. They are often viewed as being antithetical and incompatible. The various books in this program will try to place in perspective the options that are available to those who design policy and plan and manage societal matters. Typical of books being developed currently are ones on coal resources, environmental geoscience, environmental pollution, land-use planning, nuclear energy, mineral resources, and water resources. However, because soils are at the very heart of civilization and provide the building block for human sustenance, it is fitting to inaugurate this series with Dr. Olson's timely analysis of soils. Unfortu nately, these most vital resources seem to have low priority in many farming enterprises, urbanization projects, deforestation schemes, and mining and developmental terrain changes.

With the use of high-level soil management technology, Africa could feed several billion people, yet food production has generally stagnated since the 1960s. No matter how powerful the seed technology, the seedling emerging from it can flourish only in a healthy soil. Accordingly, crop yields in Africa, South Asia, and the Caribbean could be doubled or tripled through adoption of technologies based on laws of sustainable soil management. Principles of Sustainable Soil Management in Agroecosystems describes the application of these laws to enhance ecosystem services while restoring degraded soils and promoting sustainable use. With chapters contributed by world-class soil scientists, ecologists, and social scientists, this book outlines critical changes in management of agricultural soils necessary to achieve food security and meet the food demands of the present and projected future population. These changes include conversion to no-till and conservation agriculture; adoption of strategies of integrated nutrient management, water harvesting, and use of drip sub-irrigation; complex cropping/farming systems such as cover cropping and agroforestry; and use of nano-enhanced fertilizers. The book is based on the premise that it is not possible to extract more from a soil than what is put into it without degrading its quality. The strategy is to replace what is removed, respond wisely to what is changed, and be pro-active to what may happen because of natural and anthropogenic perturbations. The chapters, which exemplify these ideas, cover a range of topics including organic farming, soil fertility, crop-symbiotic soil microbiota, human-driven soil degradation, soil degradation and restoration, carbon sink capacity of soils, soil renewal and sustainability, and the marginality principle.

Soil is one of our most precious natural resources, providing a range of ecosystem functions and services, while supporting huge biodiversity. In this new book, the focus is on soil management for agriculture and the environment. Changing land-use practices and the role of soil biological diversity has been a major focus of soil science research over the past couple of decades, a trend that is likely to continue. The information presented in this book point to a holistic approach to soil management. The first part of the book looks at the land use effects on soil carbon storage, which considers how a range of factors include carbon sequestration in soils. The second part of the book presents research investigating the interactions between soil properties, plant species, and the soil biota.Soil Science Management highlights some of the most important contemporary issues concerning land management, nutrient cycling, and soil carbon and leads to more holistic approaches to sustainable land management in the future.

Drawing from a decade-long collaboration between Japan and Russia, this important volume presents the first major synthesis of current knowledge on the ecophysiology of the coniferous forests growing on permafrost at high latitudes. It presents ecological data for a region long inaccessible to most scientists, and raises important questions about the global carbon balance as these systems are affected by the changing climate.

Making up around 20% of the entire boreal forests of the northern hemisphere, these permafrost forest ecosystems are subject to particular constraints in terms of temperature, nutrient availability, and root space, creating exceptional ecosystem characteristics not known elsewhere. This authoritative text explores their diversity, structure, dynamics and physiology. It provides a comparison of these forests in relation to boreal forests elsewhere, and concludes with an assessment of the potential responses of this unique biome to climate change.

The book will be invaluable to advanced students and researchers interested in boreal vegetation, forest ecology, silviculture and forest soils, as well as to researchers into climate change and the global carbon balance. "

In the field of sedimentary research, ever increasing emphasis has been put on the investigations of carbonates and carbonate rocks during the past 30 years. It is thus quite natural that in Central Europe - where c1assical carbonate in vestigations have already been carried out 100 years ago - numerous scholars turned to the study of this sediment type. On the occasion of a visiting professorship of G. M. FRIEDMAN at the Labora torium fur Sedimentforschung, Heidelberg University, a seminar on "Recent Developments of Carbonate Sedimentology in Central Europe" was held in July 1967. 90 persons involved in carbonate investigations participated, and 35 lectures were held. The present volume contains 30 papers summarizing the different subjects of the seminar. Of course these contributions only represent a small part of the work actually performed in the field of carbonate research in Central Europe. We believe, however, that they give a general survey of the work and the working methods employed in the different sectors of carbonate investigations. One of the purposes of the present symposium is to acquaint the English speaking countries with our recent results which usually - due to the language barrier - are not accessible to them.

TO THE MODEL EVALUATION 1. MODELLING SOIL EROSION BY WATER l 2 John Boardman and David Favis-Mortlock 1 School of Geography and Environmental Change Unit Mansfield Road University of Oxford Oxford OX1 3TB UK 2 Environmental Change Unit University of Oxford 5 South Parks Road Oxford OX1 3UB UK Introduction This volume is the Proceedings of the NATO Advanced Research Workshop 'Global Change: Modelling Soil Erosion by Water', which was held on II-14th September 1995, at the University of Oxford, UK. The meeting was also one of a series organised by the IGBP 1 GCTE Soil Erosion Network, which is a component of GCTE's Land Degradation Task (3.3.2) (Ingram et aI., 1996; Valentin, this volume). One aim of the GCTE Soil Erosion Network is to evaluate the suitability of existing soil erosion models for predicting the possible impacts of global change upon soil erosion. Due to the wide range of erosion models currently, in use or under development, it was decided to evaluate models in the following sequence Favis-Mortlock et al., 1996): * field-scale water erosion models * catchmenr-scale water erosion models * wind erosion models * models with a landscape-scale and larger focus. As part of this strategy, the first stage of the GCTE validation of field-scale erosion models was carried out at the Oxford NATO-ARW. I A list of Acronyms fonns Appendix A.

At the dawn of the 21st century, biotechnology is emerging as a key enabling technology for sustainable environmental protection and stewardship. Biotechnology for the Environment: Strategy and Fundamentals captures the dynamism of environmental biotechnology as it addresses the molecular functioning of microorganisms as cleanup agents, their communal interactions in natural and polluted ecosystems, and the foundations of practical bioremediation processes. Chapters on biological pollution control in the chemical industry, biodegradation of persistent molecules (halogenated compounds, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, pesticides, detergents, etc.), microbial diversity with impact on global change, bioaugmentation strategies, and sensors for ecotoxicological monitoring, will be of value to environmental scientists, engineers, and decision-makers involved in the development, evaluation, or implementation of biological treatment systems.

For information on Soil Remediation, see Focus on Biotechnology volume 3B, and for information on Waste Water and Waste Gas Handling, see Focus on Biotechnology volume 3C.

For a long time microbial ecology has been developed as a distinct field with in Ecology. In spite of the important role of microorganisms in the environ ment, this group of 'invisible' organisms remained unaccessable to other ecologists. Detection and identification of microorganisms remain largely dependent on isolation techniques and characterisation of pure cultures. We now realise that only a minor fraction of the microbial community can be cultivated. As a result of the introduction of molecular methods, microbes can now be detected and identified at the DNA/RNA level in their natural environment. This has opened a new field in ecology: Molecular Microbial Ecology. In the present manual we aim to introduce the microbial ecologist to a selected number of current molecular techniques that are relevant in micro bial ecology. The first edition of the manual contains 33 chapters and an equal number of additional chapters will be added this year. Since the field of molecular ecology is in a continuous progress, we aim to update and extend the Manual regularly and will invite anyone to deposit their new protocols in full detail in the next edition of this Manual.

Precambrian stromatolites have received in depth, consideration from geologists and paleontologists; they were indeed searching for biosedimentary structures that were sufficiently characteristic and widely distributed to be considered as useful tools for stratigraphic correlation. Silicified stromatolites are also of interest as they contain preserved traces of ancient life. Calcareous Phanerozoic stromatolites have not received very much attention from geologists. Logan's too schematic morphological classification of 1964, was not so helpful to the knowledge of Phanerozoic stromatolites because neither their morphology nor their microstructure were studied in the same detail in which Proterozoic stromatolites have now been described. We therefore know little about the Phanerozoic stromatolites which, do, however, show an interesting range of diversification. A major questions stiII remaining to be answered include the history of stromatolite development and wether their morphology has "evolved" in addition to detailed information concerning Cenozoic nonmarine stromatolites which precipitate carbonate and the Recent giant stromatolites which trap particles. For these reasons Claude Monty, in 1981, launched the first volume of what was going to be a series on "Phanerozoic stromatolites" in order to describe their morphology, microstructure and paleoecology and to present them in their stratigraphic context.