ALBERT

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: Cellular growth is an important crystal growth process and offers an interesting example of natural pattern formation. The present work has been undertaken to study cellular growth, especially its pattern formation, both experimentally and numerically. In situ observations of faceted cellular growth clearly revealed cellular interactions in the array of cells. Cell tip splitting and loss of cells were observed to be the two main mechanisms for the adjustment of cell spacings during growth. For the first time, the true time-dependent faceted cellular growth has been modelled properly. The time evolution of faceted cellular growth has demonstrated the dynamical features of cellular growth processes. It was shown that the pattern formation was determined by cellular interactions in the array, either transient or persistent depending on the growth condition. The cellular structures were irregular when persistent interactions occurred, whereas relatively regular structures could be formed once the transient interactions had stopped. As a result of cellular interactions, a finite range of stable cell spacings was found under a given growth condition. Numerical experiments were carried out for k 〉 1 and k 〈 1 (where k is the solute partition coefficient), under a number of different growth conditions. It was found that these two cases were not symmetric as far as solute distribution is concerned; however the pattern formation behaviours were similar. For k 〉 1 shallow cells were retained, while for k 〈 1, the formation of liquid grooves along the cell boundary depended on the growth condition. The solute effect plays an important role in the cellular interactions in the array. The results were compared with experimental observations in thin film silicon single crystals. It is felt that a general behaviour of pattern formation is found and should be expected for other processes such as non-faceted cellular or eutectic growth. In addition, the solute flow in steady state cellular array growth was studied using the point source technique. Preliminary work was carried out to measure steady state non-faceted cell shapes. Heat flow in zone melting was studied numerically.

Description / Table of Contents: Biolaminated deposits, produced by microbial communities, were studied in modern peritidal environments and in the rock record. The term microbial, mat refers to modern, the term stromatolite to ancient analogs. The term biolaminated deposits was used to encompass both microbial mats and stromatolites. Microbial mat environments studied are the Gavish Sabkha, the Solar Lake, both hypersaline back-barrier systems at the Gulf of Aqaba, Sinai Peninsula, and the "Farbstreifen-Sandwatt" (versicolored sandy tidal flats) on Mellum, an island in the estuary embayment of the southern North Sea coast. Three facies-relevant categories were distinguished: (i) the mat-forming microbiota, (2) environmental conditions controlling mat types and lithology, (3) bioturbation and grazing. Cyanobacteria account for biogenic sediment accretion in all cases studied. Three major groups occur: filamentous cyanobacteria, coccoid unicells with binary fission and those with multiple fission. In the presence of these groups the following mat types evolve: (i) continuously flat (stratiform) L~-laminae (occur in all environments studied); (2) translucent, vertically extended Lv-laminae (only Gavish Sabkha and Solar Lake); (3) nodular granules (only Gavish Sabkha). Basically, the development of mats is controlled by moisture. Thus high-lying parts where the groundwater table runs more than 40 cm below surface are bare of mats. These are: The circular slope and elevated center of the Gavish Sabkha, the shorelines of the Solar Lake and the episodically flooded upper supratidal zone of Mellum Island. The following situations of water supply were found to stimulate mat growth: (i) Capillary movement of groundwater to exposed surfaces, (2) shallowest calm water, both realized in the Gavish Sabkha and the Solar Lake. On Mellum Island, mats form in the lower supratidal zone, which is flooded in the spring tide cycle and wetted during low tide by capillary groundwater. Salinity is almost that of normal seawater, whereas in the Solar Lake, it ranges from 45 °/oo to 180 °/oo and in the Gavish Sabkha, it reaches more than 300 °/oo. Salinity increase is correlated with rising concentrations of magnesium and sulfate ions. In the Gavish Sabkha, episodic sheetfloods cause high-rate sedimentation which is accidental to the living mats. Episodic low-rate sedimentation stimulates the mats to grow through the freshly deposited sediment layer. This occurs predominantly on Mellum Island due to eolian transport. Within the Gavish Sabkha, mineralogy of sediments, community structures, standing crops, redox potentials and pH are highly correlative to the increasing evenness in moisture supply which is realized by the inclination of the system below mean sea level. These conditions bring about a lateral sequence of facies types which include (I) siliciclastic biolaminites at the coastal bar base, (2) nodular to biolaminoid carbonates at saline mud flats, (3) regularly stratified stromatolitic carbonates with ooids and oncoids within the hypersaline lagoon, (4) biolaminated sulfate towardthe elevated center. High-magnesium calcite in facies type 3 precipitates around decaying organic matter and forms also the ooids and oncoids. These occur predominantly within hydroplastic Lv-laminae which provide numerous nucleation centers. Within the Solar Lake, facies type 3 (stromatolitic carbonates with ooids and oncoids) is most important, and grows to extraordinary thickness at the lake's shelf. The regular alternation of dark and light laminae results from seasonally oscillating water depths. These conditions couple back over changing light and salinity intensities to changing dominance structures of mat-building communities. Increasing salinity correlates with decreasing water depth and accounts for the relative abundance of coccoid unicells and diatoms, both active producers of extracellular slimes (Lv-laminae). Water depths locally or temporarily increased favor surface colonization by Mic~ocoleu8 chthonoplastes (Lh-laminae). The biolaminated deposits of the versicolored tidal flats on Mellum Island are similar to facies type 1 of the Gavish Sabkha (siliciclastic biolaminites). Differences exist in the lithology: Sediments upon or through which the mats on Mellum Island grow are made up of clean sand. The grains originate predominantly from re-worked glacial sediments and are rounded to well rounded. By contrast, the strong angularity of siliciclastic grains in the Gavish Sabkha clearly shows their status as primary weathering products. In all environments studied, insects play a significant role. Mainly salt beetles contribute to the lebensspuren spectrum. There is no indication that burrowing and grazing beetles and dipterans are detrimental to the growing mat systems. According to the marine fauna, two distributional barriers exist: (i) physical and (2) biogeochemical factors. Physical barriers are (a) hypersalinity and barrier-closing, which restrict the marine fauna in the Gavish Sabkha and the Solar Lake to a few species, mainly meiofaunal elements such as ostracods and copepods. Only in the Gavish Sabkha, one marine gastropod species occurs which colonizes mud flats of lower salinity. A salinity barrier of about 70 °/oo separates the gastropod habitats from the zones of growing mats. Under reduced salinity, the snails are able to destroy the microbial mats completely. (b) Decreasing regularity of flooding in the microbial mat environment of Mellum Island excludes intertidal deformative burrowers such as cockles and lugworms. However, locally the mats are pierced by numerous dwelling traces. These stem from small polychaetes and amphipod crustaceans which are able to spread over the intertidal-supratidal boundary and settle up to the MHWS-Ievel. Biogeochemical barriers are oxygen depletion within the sediments, high ammonia and sulfide contents, which generate through bacterial break-down of organic matter. Within the highly productive mats of Mic~ocoleu8 chthonoplastes on Mellum Island, dwelling traces of marine polychaetes and amphipod crustaceans disappear due to these conditions. The name of the mat-forming species, Microcoleus chthonoplastes, indicates its capacity to form "soils" (Greek chthonos). While lithology is not altered, the presence of Mic~ocoleu8 mats leads to a habitat change which excludes trace-making "arenophile" invertebrate species and favors "chthonophile" species which do not leave traces. Stromatolitic microstructures studied in rock specimens were interpreted using modern analogs: Microcolumnar buildups in Precambrian stromatolites, ooids and oncoids were compared with those of modern microbial mats. The nodular to biolaminoid facies type found in the Gavish Sabkha was suggested to be an analog to the Plattendolomite facies of Permian Zechstein, North Poland. Studies of the Lower Jurassic ironstone of Lorraine clearly indicate that fungi have been involved in the formation of stromatolites, ooids and oncoids. In conclusion, the comparative study of microstructures in microbial mats and stromatolites reveals a better understanding in both fields. In many cases, it was geology which first revealed the similarity of recent forms to those ancient ones and consequently encouraged research into them.

Description / Table of Contents: PREFACE There are problems, when applying statistical inference to the analysis of data, which are not readily solved by the inferential methods of the standard statistical techniques. One example is the computation of confidence intervals for variance components or for functions of variance components. Another example is the statistical inference on the random parameters of the mixed model of the standard statistical techniques or the inference on parameters of nonlinear models. Bayesian analysis gives answers to these problems. The advantage of the Bayesian approach is its conceptual simplicity. It is based on Bayes' theorem only. In general, the posterior distribution for the unknown parameters following from Bayes' theorem can be readily written down. The statistical inference is then solved by this distribution. Often the posterior distribution cannot be integrated analytically. However, this is not a serious drawback, since efficient methods exist for the numerical integration. The results of the standard statistical techniques concerning the linear models can also be derived by the Bayesian inference. These techniques may therefore be considered as special cases of the Bayesian analysis. Thus, the Bayesian inference is more general. Linear models and models closely related to linear models will be assumed for the analysis of the observations which contain the information on the unknown parameters of the models. The models, which are presented, are well suited for a variety of tasks connected with the evaluation of data. When applications are considered, data will be analyzed which have been taken to solve problems of surveying engineering. This does not mean, of course, that the applications are restricted to geodesy. Bayesian statistics may be applied wherever data need to be evaluated, for instance in geophysics. After an introduction the basic concepts of Bayesian inference are presented in Chapter 2. Bayes' theorem is derived and the introduction of prior information for the unknown parameters is discussed. Estimates of the unknown parameters, of confidence regions and the testing of hypotheses are derived and the predictive analysis is treated. Finally techniques for the numerical integration of the integrals are presented which have to be solved for the statistical inference. Chapter 3 introduces models to analyze data for the statistical inference on the unknown parameters and deals with special applications. First the linear model is presented with noninformative and informative priors for the unknown parameters. The agreement with the results of the standard statistical techniques is pointed out. Furthermore, the prediction of data and the linear model not of full rank are discussed. A method for identifying a model is presented and a less sensitive hypothesis test for the standard statistical techniques is derived. The Kalman-Bucy filter for estimating unknown parameters of linear dynamic systems is also given. Nonlinear models are introduced and as an example the fit of a straight line is treated. The resulting posterior distribution for the unknown parameters is analytically not tractable, so that numerical methods have to be applied for the statistical inference. In contrast to the standard statistical techniques, the Bayesian analysis for mixed models does not discriminate between fixed and random parameters, it distinguishes the parameters according to their prior information. The Bayesian inference on the parameters, which correspond to the random parameters of the mixed model of the standard statistical techniques, is therefore readily accomplished. Noninformafive priors of the variance and covariance components are derived for the linear model with unknown variance and covariance components. In addition, informative priors are given. Again, the resulting posterior distributions are analytically not tractable, so that numerical methods have to be applied for the Bayesian inference. The problem of classification is solved by applying the Bayes rule, i.e. the posterior expected loss computed by the predictive density function of the observations is minimized. Robust estimates of the standard statistical techniques, which are maximum likelihood type estimates, the so-called M-estimates, may also be derived by Bayesian inference. But this approach not only leads to the M-estimates, but also any inferential problem for the parameters may be solved. Finally, the reconstruction of digital images is discussed. Numerous methods exist for the analysis of digital images. The Bayesian approach unites some of them and gives them a common theoretical foundation. This is due to the flexibility by which prior information for the unknown parameters can be introduced. It is assumed that the reader has a basic knowledge of the standard statistical techniques. Whenever these results are needed, for easy reference the appropriate page of the book "Parameter Estimation and Hypothesis Testing in Linear Models" by the author (Koch 1988a) is cited. Of course, any other textbook on statistical techniques can serve this purpose. To easily recognize the end of an example or a proof, it is marked by a A or a t~, respectively. I want to thank all colleagues and students who contributed to this book. In particular, I thank Mr. Andreas Busch, Dipl.-Ing., for his suggestions. I also convey my thanks to Mrs. Karin Bauer, who prepared the copy of the book. The assistance of the Springer- Verlag in checking the English text is gratefully acknowledged. The responsibility of errors, of course, remains with the author.

Description / Table of Contents: INTRODUCTION Sediments are increasingly recognized as both a carrier and a possible source of contaminants in aquatic systems, and these materials may also affect groundwater quality and agricultural products when disposed on land. Contaminants are not necessarily fixed permanently by the sediment, but may be recycled via biological and chemical agents both within the sedimentary compartment and the water column. Bioaccumulation and food chain transfer may be strongly affected by sediment-associated proportions of pollutants. Benthic organisms, in particular, have direct contact with sediment, and the contaminant level in the sediment may have greater impact on their survival than do aqueous concentrations. Following the findings of positive correlations between liver lesions in English Sole and concentrations of certain aromatic hydrocarbons in Puget Sound (Washington) sediment, it can be suspected that such substrates may also be responsible for a host of other serious and presently unrecognized changes at both the organismal and ecosystem levels (Malins et al., 1984). Modern research on particle-bound contaminants probably originated with the idea that sediments reflect the biological, chemical and physical conditions in a water body (Züllig, 1956). Based on this concept the historical evolution of limnological parameters could be traced back from the study of vertical sediment profiles. In fact, already early in this century Nipkow (1920) suggested that the alternative sequence of layers in a sediment core from Lake Zürich might be related to variations in the trophic status of the lake system. During the following decades of limnological research on eutrophication problems sediment aspects were playing only a marginal role, until it was recognized that recycling from bottom deposits can be a significant factor in the nutrient budget of an aquatic system. Similarly, in the next global environmental issue, the acidification of inland waters sediment-related research only became gradually involved. Here too, it is now accepted that particle-interactions can affect aquatic ecosystems, e.g. by enhancing the mobility of toxic metals. In contrast to the eutrophication and acidification problems, research on toxic chemicals has included sediments aspects from its beginning: Artificial radionuclides in the Columbia and Clinch Rivers in the early sixties (Sayre et al., 1963); in the late sixties heavy metals in the Rhine River system (De Groot, 1966) and methyl mercury (Jensen & Jerne- 16v, 1967) at Minamata Bay in Japan, in Swedish lakes, in Alpine Lakes, Laurentian Great Lakes and in the Wabigoon River system in Canada; organochlorine insecticides and PCBs in Lakes St. Clair and Erie during the seventies (Frank et al., 1977); chlorobenzenes and TCDDs in the Niagara River system and Lake Ontario in the early eighties (Oliver & Nicol, 1982; Smith et al., 1983). In the present lecture notes, following the description of priority pollutants related to sedimentary phases (Chapter 2), four aspects will be covered, which in an overlapping succession also reflect the development of knowledge in particle-associated pollutants during the past twenty-five years: - the identification, surveillance, monitoring and control of sources and distribution of pollutants (Chapter 3); - the evaluation of solid/solution relations of contaminants in surface waters (Chapter 4); - the study of in-situ processes and mechanisms in pollutant transfer in various compartments of the aquatic ecosystems (Chapter 5);- The assessment of the envlroD-mental impact of particle-bound contaminants, i.e. the development of sediment quality criteria (Chapter 6). A final chapter will focus on practical aspects with contaminated sediments. Available technologies will be described as well as future perspectives for the management of dredged materials. Here too, validity of remedial measures can only be assessed by integrated, multidisciplinary research. In the view of the growing information on the present subject and owing to the limitations in the framework of this monography, the reader is referred to additional selected bibliography, which is attached at the end of this Chapter i. Additional information on the more recent publications on contaminated sediments is given in the annual review volume of the Journal of the Water Pollution Control Federation, June edition.

Description / Table of Contents: The present interest in sediments which are rich in organic matter results not only from their economic significance as potential oil and gas source rocks, but also from the fact that their deposition is the result of special environments. Subtle changes in the environmental conditions may result in great variations in the geochemical and petrographical characteristics of the organic matter. Therefore, the study of organic matter-rich sediments can provide a key to past sedimentary conditions. In addition, the elucidation of the depositional controls is of importance for oil and gas exploration strategies, for which the knowledge of source rock distribution and quality is critical. Furthermore, organic matter reacts extremely sensitive to changes in temperature during burial. The result of this sensitivity is the generation of volatile products such as carbon dioxide, water, nitrogen, oil and gas and a reorganization of the solid organic residue. Some of these changes are quantified as maturity parameters which can be used as calibration tools in basin modelling, i.e., in the modelling of temperature histories of sedimentary basins. The use of maturity parameters and other organic matter characteristics as indicators for diagenetic conditions and depositional processes is, however, restricted, if analyses are performed on outcrop samples, because weathering also affects organic matter.

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 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: PREFACE It is increasingly necessary to develop industrial and hydraulic engineering constructions under unfavourable geological or geotechnical conditions. Furthermore, it becomes more and more important to build effectively and economically and to find optimal solutions for a long-term steady function of the constructions. This emphatically demands exhaustive information on the structural situations and engineering parameters of local site assessments by areal investigations of the sites and the petrophysical parameters in situ. This requires, however, the use of geophysical techniques. During the last two or three decades international applied geophysics has systematically developed new possibilities for site investigations for the determination of petrophysical parameters in situ as well as for observation of the system building and site. As in "New techniques in engineering", geophysical methods make it possible to develop areal models of subsurface conditions of building sites, to quantify relevant engineering parameters in situ, as well as to analyze the longterm behaviour of the buildings, which are influenced by internal or external factors. With regard to the broad spectrum of applied geophysics, there are few methods, that especially favour application in engineering and groundwater studies. These methods are distinguished by a relatively simple measuring technique and good measuring progress, e.g. the geoelectrical self-potential method, the geoelectrical resistivity method as well as a newly developed devices for geothermic measurements. There exist numerous publications, broadly scattered in the technical literature, concerning the theoretical bases and applications of these methods, but until now, there have been only a few meetings to exchange experience and results on an international level. This was the aim of the symposium "Detection of Subsurface Flow Phenomena by Self-Potential/Geoelectrical and Thermometric Methods", held in Karlsruhe from 14-18 March 1988. An outstanding part of the symposioum was represented by the results of a research project, coordinated by the University of Karlsruhe (Department of Geology and Institute of Soil and Rock Mechanics) and the Federal Waterway Engineering and Research Institute (BAW), Karlsruhe. Regarding the subject "Experiments to ascertain the relations between hydraulic potentials in the underground and the geoelectrical and thermic potentials set off by these", the research work took four years. The project was sponsered by the Volkswagen Foundation/Hannover. The goal was to develop and test objective techniques for detecting leakages in dams, locating, demarcating and designating quantitatively inhomogeneous spheres in dams with the aim of detecting damage and subsurface flow phenomena as soon as possible. The symposium consisted of a three-day lecture meeting with about 40 papers and a summarizing respectively closing roundtable discussion, a visit to the laboratories and to the in situ constructions within the area of BAW developed in the frame of the research project. This included a technical excursion to the Rhine-Staustufe Iffezheim with its very impressive waterway constructions and an excursion to the Geophysical Observatory near Schiltach (Black Forest). The Observatory belongs to the Universities of Karlsruhe and Stuttgart. Approximately 80 scientists from 15 countries participated the symposium. They were welcomed by the Rector of the University, Professor Dr. A. Kunle and the representative of the Federal Ministry of Traffic, Dr. G. Schröder. Professor Dr. H. Hötzl elucidated the scientific problems and the economical importance of the project as a speaker of the research group. The following papers dealt with the fundamental aspects of geoelectrical and thermometric measurements, with the theory of these methods, the state and developing ter~dencies concerning devices, data acquisition, processing and interpretation as well as noise effects. It became clear that the solution of the complex scientific-technical problems of waterway constructions and environmental protection requires broad, interdisciplinary cooperation and international collaboration. Thus it would be possible to minimize the personnel, temporal and economic efforts. The intended cooperation of geoscientists, engineering geologists, building engineers and representatives of other disciplines make it possible, not only to exchange experiences and results relating to international problems unsolved until now, but also to determine new guidelines with regard to the scientific organization of further investigations. Thus in order to inform all interested parties of the main topics of the symposium and to advance international cooperation in the future, the present review includes a part of the papers and reports of the excursions recommended by the participants of the meeting, which have been divided into the following topics: - Introduction to engineering-geophysical problems and attempts at their solution; - Geoelectrical self-potential measurements; - Geoelectrical resistivity measurements; - Geothermic measurements; - Case histories; - Some topics of the roundtable discussion; - Reports concerning the excursions. The editors wish to thank very much all those, who contributed to the success of the symposium and to the publication of the present report. Finally they venture the note, that the authors theirselves are responsible for the content of their papers.