ALBERT

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: 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: Pages 1-13 / Maars of the Westeifel, Germany / G. Büchel --- Pages 15-60 / Syn- and post-eruptive mechanism of the Alaskan Ukinrek Maars in 1977 / G. Büchel, V. Lorenz --- Pages 61-80 / Maars and maar lakes of the Westeifel Volcanic Field / Jörg F. W. Negendank, Bernd Zolitschka --- Pages 81-94 / Maars of northern Auvergne (Massif Central, France): State of knowledge / E. Juvigné, G. Camus, A. de Goër de Herve --- Pages 95-107 / Palaeoenvironmental investigations on long sediment cores from volcanic lakes of Lazio (central Italy)—An overview / Maria Follieri, Donatella Magri, Biancamaria Narcisi --- Pages 109-116 / Geophysical mapping of organic sediments / Stefan Wende, Reinhard Kirsch --- Pages 117-118 / Preliminary uniboom survey of the Monticchio Lakes (southern Italy) / A. Stefanon --- Pages 119-128 / Sonar investigations in the Laghi di Monticchio (Mt. Vúlture, Italy) / Ralph B. Hansen --- Pages 129-148 / Climatic and tectonic effects on sedimentation in central Italian volcano lakes (Latium)—Implications from high resolution seismic profiles / F. Niessen, A. Lami, P. Guilizzoni --- Pages 149-161 / Sediments and basin analysis of Lake Schalkenmehrener Maar / T. Heinz, B. Rein, J. F. W. Negendank --- Pages 163-171 / Organic carbon contents of sediments from Lake Schalkenmehrener Maar: A paleoclimate indicator / B. Rein, J. F. W. Negendank --- Pages 173-194 / Basin analysis for selected time-frames using sedimentation rates in Lake Meerfelder Maar (Westeifel FRG) / F. Wegner, J. F. W. Negendank --- Pages 195-208 / Turbidites in the sediments of Lake Meerfelder Maar (Germany) and the explanation of suspension sediments / D. Drohmann, J. F. W. Negendank --- Pages 209-222 / Paleoclimate reconstruction at the Pleistocene/Holocene transition—A varve dated microstratigraphic record from Lake Meerfelder Maar (Westeifel, Germany) / D. Poth, J. F. W. Negendank --- Pages 223-235 / Paleoenvironmental reconstruction of the Late- and Postglacial sedimentary record of Lake Weinfelder Maar / A. Brauer, J. F. W. Negendank --- Pages 237-275 / Sedimentology and paleoenvironment from the Maar Lac du Bouchet for the last climatic cycle, 0-120,000 years (Massif Central, France) / Elisabeth Truze, Kerry Kelts --- Pages 277-288 / Lago Grande di Monticchio (southern Italy) a high resolution sedimentary record of the last 70,000 years / Bernd Zolitschka, Jörg F. W. Negendank --- Pages 289-304 / A multidisciplinary study of the Vico Maar sequence (Latium, Italy): Part of the last cycle in the Mediterranean area. Preliminary results / P. Francus, S. Leroy, I. Mergeai, G. Seret, G. Wansard --- Pages 305-316 / Environmental geology and geochemistry of lake sediments (Holzmaar, Eifwl, Germany) / B. G. Lottermoser, R. Oberhänsli, B. Zolitschka, J. F. W. Negendank, U. Schütz… --- Pages 317-332 / Geochemistry of Lago Grande di Monticchio, S. Italy / C. Robinson, G. B. Shimmield, K. M. Creer --- Pages 333-348 / Tephrochronology of core C from Lago Grande di Monticchio / Anthony J. Newton, Andrew J. Dugmore --- Pages 349-365 / A palaeomagnetic study of maar-lake sediments from the Westeifel / B. Haverkamp, Th. Beuker --- Pages 367-376 / Preliminary 50m palaeomagnetic records from Lac du Bouchet, Haute Loire, France / T. Williams, K. M. Creer, N. Thouveny --- Pages 377-392 / Palaeomagnetic investigations of Lago Grande di Monticchio, southern Italy / Ian Turton --- Pages 393-420 / Late-Glacial/Holocene changes of the climatic and trophic conditions in three Eifel maar lakes, as indicated by faunal remains. I. Cladocera / Wolfgang Hofmann --- Pages 421-433 / Late-glacial/Holocene changes of the climatic and trophic conditions in three Eifel maar lakes, as indicated by faunal remains. II. Chironomidae (Diptera) / Wolfgang Hofmann --- Pages 435-439 / Ostracoda (Crustacea) and trichoptera (Insecta) from Late-and Postglacial sediments of some European maar lakes / Burkhard W. Scharf --- Pages 441-446 / Oligocence dinoflagellate-cysts in Quaternary freshwater sediments of Eifel maars / H. Weiler --- Pages 447-465 / Tertiary maars of the Hocheifel Volcanic Field, Germany / G. Büchel, M. Pirrung --- Pages 467-476 / Some aspects of Cenozoic maar sediments in Europe: the source-rock potential and their exceptionally good fossil preservation / W. Zimmerle --- Pages 477-484 / Palaeoecological implications from the sedimentary record of a subtropical maar lake (Eocene Eckfelder Maar; Germany) / Bernd Zolitschka --- Pages 485-489 / Arthropods from the Eocene Eckfelder Maar (Eifel, Germany) as a source for paleoecological information / H. Lutz --- Pages 491-497 / Flowers from the Middle Eocene of Eckfeld (Eifel, Germany)— First results / H. Frankenhäuser, V. Wilde --- Pages 499-503 / Initial results on the importance of a flora from the Middle Eocene of Eckfeld (Eifel, W.-Germany) / V. Wilde, H. Frankenhäuser --- Pages 505-509 / International Maar Deep Drilling Project (MDDP) a challenge for earth sciences? / Jörg F. W. Negendank, Bernd Zolitschka

Description / Table of Contents: PREFACE Turbidity currents have been comprehensively studied in the past although much remains unknown about both their flow characteristics and resultant sedimentary deposits. Much of this uncertainty arises from the catastrophic nature of their formation which makes them difficult to study in the environment, and has resulted in the majority of studies being experimental or theoretical. Experiments have shown that reversals in the flow of density currents can be associated with the generation of internal solitary waves. This is in contrast to the belief held by many workers that the reversal of a turbidity current simply generates an identical flow travelling in the opposite direction. This book arose from the need for a detailed experimental study to examine the effects and to consider the consequences of density current reversals from a variety of obstructions to their flow. The first part of this book comprises a detailed review of literature covering the fluid dynamics and sedimentology relevant to the experimental study (chapter one). Chapter two presents the results from the comprehensive experimental programme which are discussed and compared with appropiate theoretical hypotheses. This permits the synthesis of a model for the general features of flows that result from the incidence of density currents upon obstructions to the flow. The application of this model to both modern and ancient turbidite systems is then discussed in chapter three. This book is suitable for earth scientists with an interest in the dynamics of turbidity currents. In addition, workers from other fields such as applied maths, meteorology and engineering who have an interest in density currents and bores in practical situations may find it useful...