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Geotectonics has a special place among the geological dis ciplines. In addition to ideas based on firmly established facts that constitute lasting scientific values, geotectonics, as a generalizing branch of geology, embraces broad con structions that link the planet's deep interior with its sur face and are largely of a hypothetical character. The inter pretation of the most general matters of the structure and evolution of the globe varies not only from one generation of geologists to another, but even within one generation. The interpretation depends not only, and not so much, on the state of geological knowledge, as on the progress of the related sciences of geophysics and geochemistry. In trying to discover the deep-lying causes of tectonic processes, geotectonics has to unite the results of all the Earth sci ences, converting itself to some extent from a purely geologi cal science into a general physical geographic or geonomic science. The fluidity of the general ideas and the need for joint consideration of the geological, geophysical, and geochemi cal data to substantiate these ideas are the main difficulties facing the author of a textbook on geotectonics. There is undoubtedly, however, a need for a manual of this kind, particularly now when the literature on the various problems of geotectonics has grown so great and so varied in content that it is very difficult for the experienced researcher, let alone the student, to find his way.

Within the last decade, the high and continuing demand for gold has prompted a global gold rush on a scale never before seen, not even in the heady days of Ballarat, California and the Yukon. Gold is being sought on every continent and, with very few exceptions, in every country around the world. Such interest and fierce competition has demanded considerable innovation and improvement in exploration techniques paralleled by a rapid expansion of the geological database and consequent genetic modelling for the many different types of gold deposits now recognized. This proliferation of data has swamped the literature and left explorationist and academic alike unable to sift more than a small proportion of the accumulating information. This new book represents an attempt to address this major problem by providing succinct syntheses ofall major aspects ofgold metallogeny and exploration, ranging from the chemical distribution of gold in the Earth's crust, and the hydrothermal chemistry of gold, to Archaean and Phanerozoic lode deposits, epithermal environments, chemical sediments, and placer deposits, and culminates in chapters devoted to geochemical and geophysical exploration, and the economics of gold deposits. Each chapter is written by geoscientists who are acknowledged internationally in their respective fields, thus guaranteeing a broad yet up-to-date coverage. In addition, each chapter is accompanied by reference lists which provide readers with access to the most pertinent and useful publications.

Designed for geologists and engineers engaged specifically in the search for gold deposits of all types and as a reference for academics in higher schools of learning, Handbook of gold exploration and evaluation provides principles and detailed explanations that underpin the correct interpretation of day-to-day experience in the field. Problems are addressed with regard to the analysis, interpretation and understanding of the general framework within which both primary and secondary gold resources are explored, developed and exploited.Handbook of gold exploration and evaluation covers a comprehensive range of topics including the nature and history of gold, geology of gold ore deposits, gold deposition in the weathering environment, sedimentation and detrital gold, gold exploration, lateritic and placer gold sampling, mine planning and practise for shallow deposits, metallurgical processes and design, and evaluation, risk and feasibility. - Covers the nature and history of gold - Addresses problems with regard to the framework in which gold resources are explored, developed and exploited - Discusses topics including the geology of gold ore deposits, metallurgical processes and design, evaluation, risk and feasibility

This volume summarizes our current understanding of biological soil crusts (biocrusts), which are omnipresent in dryland regions. Since they cover the soil surface, they influence, or even control, all surface exchange processes. Being one of the oldest terrestrial communities, biocrusts comprise a high diversity of cyanobacteria, algae, lichens and bryophytes together with uncounted bacteria, and fungi. The authors show that biocrusts are an integral part of dryland ecosystems, stabilizing soils, influencing plant germination and growth, and playing a key role in carbon, nitrogen and water cycling. Initial attempts have been made to use biocrusts as models in ecological theory. On the other hand, biocrusts are endangered by local disruptions and global change, highlighting the need for enhanced recovery methods. This book offers a comprehensive overview of the fascinating field of biocrust research, making it indispensable not only for scientists in this area, but also for land managers, policy makers, and anyone interested in the environment.