Radiocarbon After Four Decades: An Interdisciplinary Perspective commemorates the 40th anniversary of radiocarbon dating. The volume presents discussions of every aspect of this dating technique, as well as chronicles of its development and views of future advancements and applications. All of the 64 authors played major roles in establishment, development or application of this revolutionary scientific tool. The 35 chapters provide a solid foundation in the essential topics of radiocarbon dating: Historical Perspectives; The Natural Carbon Cycle; Instrumentation and Sample Preparation; Hydrology; Old World Archaeology; New World Archaeology; Earth Sciences; and Biomedical Applications.

This book is written as a practical field manual to effective. Each geolOgist has to develop his/her be used by geologists engaged in mineral explo own techniques and will ultimately be judged on ration. It is also hoped that it will serve as a text results, not the process by which these results and reference for students in Applied Geology were reached. In mineral exploration, the only courses of universities and colleges. The book 'right' way of doing anything is the way that aims to outline some of the practical skills that locates ore in the quickest and most cost-effective turn the graduate geologist into an explo manner. It is preferable, however, for an individ rationist: . It is intended as a practical 'how to' ual to develop his/her own method of operation book, rather than as a text on geological or ore after having tried, and become aware of, those deposit theory. procedures which experience has shown to work An explorationist is a professional who search well and which are generally accepted in indus try as good exploration practice. es for ore bodies in a scientific and structured way. Although an awkward and artificial term, The chapters of the book approximately fol this is the only available word to describe the low the steps which a typical exploration pro totality of the skills which are needed to locate gramme would go through. In Chapter 1, the and define economic mineralization."

Research on base metal sulfide deposits is among the oldest and best-documented subjects of economic geologists worldwide, c- sidering that copper was first mined about 3000 years ago on the island of Cyprus. During the past 10 years, after the exciting discovery of active sulfide formation on the modem ocean floor, a considerable flow of new ideas has stimulated and influenced the discussion of o- forming processes for copper-zinc-Iead sulfides in sedimentary and volcanic environments. The development of new genetic concepts consequently led to reinterpretation of some apparently well-est- lished formation models. This Proceedings Volume contains a collection of carefully selected papers on current research on the geology and metallogeny of base metal sulfide deposits presented as oral or poster contri- tions at the DMG (Deutsche Mineralogische Gesellschaft) - GDMB (Gesellschaft Deutscher Metallhiitten- und Bergleute - Fachsektion Lagerstiittenforschung) - SGA (Society of Geology Applied to Mineral Deposits) Joint Meeting on Ore Deposits in Aachen, Federal Republic of Germany, September 16-19, 1985. Base metal sulfide deposits with different ore compositions occur in a wide variety of geological and lithological settings of almost any age. This has been taken into account in organizing this volume along the lines of classical host-rock classification. The first group of contributions focuses on sediment-hosted base metal sulfide deposits including examples of Kupferschiefer and Copperbelt-type, as well as lead-zinc mineralization in car- nate host rocks.

The Thirteenth International Conference on Basement Tectonics was held on the campus of Virginia Polytechnic Institute and State University in Blacksburg, Virginia from June 2 -6, 1997. The oral presentations and discussions over three days covered a wide range of topics, and provided the international audience with a perspective on scientific efforts underway around the world. The conference participants were able to attend two separate field trips: (I) a pre-conference trip guided by Professor Robert Hatcher of the University of Tennessee, Knoxville, examined the Basement rocks in the North Carolina -Tennessee region of the Appalachian Mountains, and (2) a mid-conference field trip guided by A.K. Sinha, convener of the conference, allowed participants to examine the complex rock associations and structures of the> 1000 m.y. old basement rocks in Virginia. Both the field trip guidebooks and abstract volumes were published for the conference. The meeting brought together scientists from more than 14 countries. Their participation, and the fiscal success of the meeting would not have been possible without the support of the Department of Geological Sciences, the College of Arts and Sciences (VPI&SU) and the Basement Tectonics Association. Their support is gratefully acknowledged. As Chairman of the Organizing Committee, I would like to thank Margie Sentelle, Jay Thomas, Peter Welch, and Barry Robinson for the smooth operation of the conference.

The molecular mechanisms underlying the fact that a crystal can take a variety of external forms is something we have come to understand only in the last few decades. This is due to recent developments in theoretical and experimental investigations of crystal growth mechanisms.
Morphology of Crystals is divided into three separately available volumes. Part A contains chapters on roughening transition; equilibrium form; step pattern theory; modern PBC; and surface microtopography. This part provides essentially theoretical treatments of the problem, particularly the solid-liquid interface. Part B contains chapters on ultra-fine particles; minerals; transition from polyhedral to dendrite; theory of dendrite; and snow crystals. All chapters are written by world leaders in their respective areas, and some can be seen as representing the essence of a life's work. This is the first English-language work which covers all aspects of the morphology of crystals - a topic which has attracted top scientific minds for centuries. As such, it is indispensable for anyone seeking an answer to a question relating to this fascinating problem: mineralogists, petrologists, crystallographers, materials scientists, workers in solid-state physics and chemistry, etc.
In Parts A: Fundamentals and B: Fine Particles, Minerals and Snow equilibrium and kinetic properties of crystals are generally approached from an atomistic' point of view. In contrast, Part C: The Geometry of Crystal Growth follows the alternative and complementary geometrical' description, where bulk phases are considered as continuous media and their interfaces as mathematical surfaces with orientation-dependent properties. Equations of motion for a crystal surface are expressed in terms of vector and tensor operators working on surface free energy and growth rate, both expressed as functions of surface orientation and driving force, or affinity' for growth. This approach emphasizes the interrelation between equilibrium and kinetic behavior. Part 1 establishes the theoretical framework. Part 2 gives a construction toolbox for explicit (analytic) functions. An extra chapter is devoted to experimental techniques for measuring such functions: a new approach to sphere growth experiments. The emphasis throughout is on principles and new concepts.
Audience: Advanced readers familiar with traditional aspects of crystal growth theory. Can be used as the basis for an advanced course, provided supplementation is provided in the areas of atomistic models of the advancing surface, diffusion fields, etc.

All existing introductory reviews of mineralogy are written accord ing to the same algorithm, sometimes called the "Dana System of Mineralogy." Even modern advanced handbooks, which are cer tainly necessary, include basic data on minerals and are essentially descriptive. When basic information on the chemistry, structure, optical and physical properties, distinguished features and para genesis of 200-400 minerals is presented, then there is practically no further space available to include new ideas and concepts based on recent mineral studies. A possible solution to this dilemma would be to present a book beginning where introductory textbooks end for those already famil iar with the elementary concepts. Such a volume would be tailored to specialists in all fields of science and industry, interested in the most recent results in mineralogy. This approach may be called Advanced Mineralogy. Here, an attempt has been made to survey the current possibilities and aims in mineral mater investigations, including the main characteristics of all the methods, the most important problems and topics of mineralogy, and related studies. The individual volumes are composed of short, condensed chap ters. Each chapter presents in a complete, albeit condensed, form specific problems, methods, theories, and directions of investigations, and estimates their importance and strategic position in science and industry."

reviewers, and reported by users of the earlier This third edition (or issue) of the Quantitative Data File for ore minerals (QDF) of the Commission on editions. The result is that 510 species and 125 are Mineralogy of the International Mineralogical compositional or structural variants, or varieties, of Association (COM-IMA) is published, with the species, are represented in QDF3. A large number of support of the Natural History Museum, London, by the entries include data collected from the type Chapman & Hall. It has been greatly revised and specimen of a mineral: these include data extracted enlarged and now includes graphs of the reflectance from the published literature. In this respect, QDF3 spectra for all of its entries. These have been differs from earlier editions. included in response to requests from users of the We have also revised and simplified the notes earlier editions. Also included, for those users concerning X-ray data: no longer are the strongest unfamiliar with the application of such spectra to lines in the powder diffraction pattern quoted, nor mineral identification, are introductory notes, are cell dimensions generally given. Instead, it was illustrated with examples of R spectra. decided to refer to data from the original description, The 635 data sets, which are arranged or to data in the PDF of the JCPDS.

Although some handbooks on the microscopic identi In Part I the concept of heavy mineral analysis is fication of heavy mineral grains are available, a introduced and the relative significance of factors comprehensive manual illustrated in colour has not affecting heavy mineral assemblages is discussed. There been published until now. Because the appearance of are brief references to the commonly used laboratory minerals in grain mounts differs considerably from methods and auxiliary techniques. It concludes with those seen in a thin section, a different approach is some examples of the application of heavy mineral necessary for the identification of detrital grains. studies. Coloured photomicrographs, showing their colour Part II contains the descriptions of 61 transparent shades, pleochroism and interference tints, provide heavy mineral species, including those which are an excellent means of assisting recognition. As a commonly authigenic in sediments. Positive identi number of mineral grains have similar optical proper fication of authigenic minerals is important to avoid ties and morphology, it is equally important to confusion and to help recognition of diagenetic describe them verbally in detail, pointing out events. In the mineral descriptions considerable characteristic features and differences. emphasis is placed upon detrital morphology and This book is intended primarily as a manual that diagnostic features. Optical properties and character describes and illustrates the transparent heavy min istics are detailed, together with information on host erals most commonly found in sediments. It is hoped rocks.

Sedimentology has neither been adequately popularized nor This book begins with a consideration of the complex end commonly taught as an interdisciplinary subject, and many product of processes and materials, the sedimentary environ workers in the areas of modem environment studies have very ment. It then proceeds to discuss the processes and materials limited knowledge of sedimentology. Practical Sedimentol themselves. The emphasis is on geological interpretations of ogy (henceforth PS) is designed to provide an introduction and ancient deposits, but most discussions are also relevant to review of principles and interpretations related to sedimentary modem sediments and can be used to predict environmental processes, environments, and deposits. Its companion volume, changes. A basic knowledge of geological jargon is antici Analytical Sedimentology (henceforth AS), provides "cook pated for users of this book; we try to define most of the more book recipes" for common analytical procedures dealing with esoteric terms in context, but if there are additional incom sediments, and an introduction to the principles and reference prehensible terms, refer to Bates and Jackson's Glossary of sources for procedures that generally would be performed by Geology (AGI, 1987). specialist consultants or commercial laboratories. Specialist sedimentologists will find in them useful reviews, whereas sci ACKNOWLEDGMENTS entists from other disciplines will find in them concepts and procedures that may contribute to an expanded knowledge of Many chapter drafts ofPS were critically reviewed by Dr. M.

The 12thInternational BasementTectonicsConferencewas hostedbythe Schoolof Geologyand Geophysics and theOklahoma Geological Survey inthe SarkeysEnergy Centeronthe campusoftheUniversityofOklahoma, Norman, Oklahoma, U. S. A. , from May 21stthroughMay 26th, 1995. Atotal of52 individualswere in attendance, 9 ofwhichwereattendingfrom 6differentforeign countries. Fourdaysoforal and posterpresentationswere divided intofour technical sessions withthefollowing themes: I)FractureDevelopment, Reactivation, andMineralization, organizedbyM. 1. Bartholomewand S. Marshak; 2)EvolutionoftheBasementofthe North American Plate (with special emphasison its southern margin), organizedby R E. Denisonand E. G. Lidiak; 3)ProbingofBasement: Geophysical and Geochemical Methods,organizedbyR A. Youngand G. R Keller; and 4)ResponseofCoverRocks toBasementDeformation, organized by P. Berendsenand M. P. Carlson. Seventy-five presentationswere made during thecourseofthe meeting, which wasorganizedby Program Chairman M. Charles Gilbertandprofessionally managedbySaraMoody. Precedingthe meeting wasatwo dayfield trip toexaminethe modeand kinematics ofterraneaccretion duringclosureofan oceanbasin, as preserved in thePrecambrian geologyoftheeasternLlano Uplift, Texas, U. S. A. Thefield trip leaders Sharon Mosher, MarkHelper, Don Barker, and Robert Reed providedan excellentand comprehensive guidebook, and shared theirconsiderable expertise in manydiscussions at one spectacularexposures afteranother. All registrants participatedinthe mid-conferencefield tripguidedby R E. Denison, E. G. Lidiak, M. C. Gilbert, and John P. Hogan to examinethePrecambrianand Cambrianbasementterranesexposed in the ArbuckleMountainsupliftin southernOklahoma, U. S. A. Evidencefor apossible continental arc settingfor the southern margin ofthe-1. 4 Ga Granite-Rhyolite Terrane, theopeningofthe Cambrian Southern Oklahoma Aulacogenasevidencedby aspectacularexposureofadiabasedike swarm, and the roleofearliertectonicfabrics in thedevelopmentofyoungerstructureswere someofthe topicsofdiscussion. Thetwo day postconferencefield trip to the WichitaMountains uplift, southwestern Oklahoma, U. S. A. was ledby M. Charles Gilbert, and John P. Hogan. Thistrip highlightedthe Cambrian SouthernOklahoma Aulacogen.

Modern approaches to the theoretical computation and experimental determination of NMR shielding tensors are described in twenty-nine papers based on lectures presented at the NATO ARW. All of the most popular computational methods are reviewed and recent progress is described in their application to chemical, biochemical, geochemical and materials science problems. Experimental studies on NMR shieldings in gases, liquids and solids are also included, with special emphasis placed upon the relationship between NMR shielding and geometric structure and upon tests of the accuracy of the various computational methods. Qualitative MO schemes and semiempirical approaches are also considered in light of the computational results. This is a valuable book for anyone interested in how the NMR shielding tensor can be used to determine the geometric and electronic structures of molecules and solids. (abstract) Modern methods for computing and measuring nuclear magnetic resonance shielding tensors are described in papers by a great number of leaders in the field. The most popular methods for quantum mechanically calculating NMR shielding tensors are reviewed and many applications of these methods are described to problems in chemistry, biochemistry, geochemistry and materials science. The focus of the papers is on the relationship of the NMR shielding tensor to the geometric and electronic structure of molecules or solids.

As a method of structure analysis, electron diffraction has its own spe cial possibilities and advantages in comparison to the X -ray method for the study of finely dispersed minerals with layer or pseudolayer structures. How ever, possibly because of the prior existence of the X-ray method, which found universal application in different fields and attracted the main efforts of spe cialists, electron diffraction has been unevenly disseminated and developed in different countries. In particular, the oblique texture method, which gives very complete and detailed structural information, has been mainly used in the Soviet Union, where electron-diffraction cameras specially suited to the method have been constructed. In other countries, studies have been made of micro-single crystals, because these studies could be carried out with existing electron microscopes. It should be recognized that the scale of distribution and use attained by electron-diffraction methods, at present limited by exist ing experimental conditions. is more than justified by the value of the results which may be obtained by their aid. The author hopes that the present book will give the reader a fuller idea of the valuable advantages of the method, and of the structural crystallography picture which has been built up for clay minerals, and layer silicates in general, from electron-diffraction data. The time between the appearance of this book and that of the Russian edition has been comparatively short."

of a Roman numeral, an alphabetic character and an Arabic numeral. This designation constitutes the classification symbol based on the system in Mineralogische Tabellen by Hugo Strunz (a summary is shown in Appendix A). The Roman numeral and alphabetical character divide the minerals into broad groups based mainly on chemistry, with the silicate subdivision based on silicate polymerization. The Arabic numeral specifies the group to which a particular mineral belongs; a group is defined mainly on the basis of crystallographic similarities, but minerals with similar chemical compositions are sometimes included in the group even though they do not exhibit crystallographic affinities with other members of the class. The next entry gives the name of the author of the mineral and the date of its introduction into the literature. In some cases where a mineral has been redescribed or the name has been changed from the original, this entry will reflect the person and time when this was done. This is followed by a reference to what we have tried to make the latest, or most authoritative, literature report. We have attempted to include at least one reference for each species. If there is a second reference following the first, it will be a reference to the determination of the crystal structure. The abbreviations used in the references are given in Appendix B. The final entry, when present, gives the names of similar or related minerals and is preceded by the deSignation "See also" .

More than seventeen years have passed now since Glauco Gottardi and Ermano Galli 1 have published their remarkable book on "NATURAL ZEOLITES" where properties and features of naturally occuring phases then available have been compiled. Several new natural zeolites have been found since then, but also natural counterparts ofzeolites which have only been known as synthesis products. The natural formation conditions of zeolites could only be deduced and estimated from their geological environment at the time when NATURAL ZEOLITES has been published, as zeolite synthesis was mainly focused on procedures at low pressures such as those introduced by Barrer and co workers'. Natural zeolites, however, had only been obtained "occasionally" and systematic study to reconstruct these formation conditions has not been performed ever since. This book is focused on the synthesis of natural zeolites by simulating the natural synthesis conditions in the laboratory which are essentially different in means and results from those obtained by conventional synthesis methods. Although the synthesis in the laboratory has undoubtly a great number of advantages over nature such as the employment of proper precursors or the choice of pressure and temperature in a wide range, the synthesis time is very limited in respect to natural conditions: synthesis times ofyears or even tens ofyears which would be necessary to obtain synthesis results for some zeolites- e.g. at 4 DegreesC (deep sea conditions) are rather unrealistic.

Volcanic eruptions are fascinating manifestations of the Earth's dynamic inte rior which has been cooling for the past several billion years. The planets of the solar system originated some 4.5 billion years ago from the same gas and dust cloud created by the big bang. Some of the gas collapsed by the gravitational force to form the Sun at the center, while the whirling disk of gas and dust around the Sun subsequently cooled and lumped together to form larger and larger lumps of materials or planetesimals. These planetesimals collided fre quently and violently and in the process liberated heat that melted the material in them. With time this material gradually cooled and formed the planets of the solar system. During the second half of the twentieth century the theory of plate tectonics of the Earth became established and demonstrated that our planet is covered with six large and many small plates of the lithosphere. These plates move over a highly viscous lower part of the Earth's upper mantle and contain the continental and oceanic crusts. The lower mantle extends below the upper mantle until it meets the core that is more than half the diameter of the entire globe (12,740 km). The inner core consists mostly of iron and its temperature is about 5000 kelvin, whereas the liquid outer core is turbulent, rotates faster than the mantle, consists primarily of iron, and is the source of the Earth's magnetic field."

The triennial International Alloy Conferences (lACs) aim at the identification and promotion of the common elements developed in the study, either experimental, phenomenological, or theoretical and computational, of materials properties across materials types, from metals to minerals. To accomplish this goal, the lACs bring together scientists from a wide spectrum of materials science including experiment, theory, modeling, and computation, incorporating a broad range of materials properties. The first lAC, lAC-I, took place in Athens, Greece, June 16-21, 1996. The present volume of proceedings contains the papers presented at IAC-2, that took place in Davos, Switzerland, August 8-13, 1999. The topics in this book fall into several themes, which suggest a number of different classification schemes. We have chosen a scheme that classifies the papers in the volume into the categories Microstructural Properties; Ordering, Kinetics and Diffusion; Magnetic Properties and Elastic Properties. We have juxtaposed apparently disparate of revealing the dynamic character approaches to similar physical processes, in the hope of the processes under consideration. We hope this will invigorate new kinds of discussion and reveal challenges and new avenues to the description and prediction of properties of materials in the solid state and the conditions that produce them.

Feldspar minerals make up 60% of the crust of the Earth. They are stable in the upper mantle, and are so abundant in the crust that they form the basis of the classification of igneous rocks. At the surface, feldspars weather to form clay minerals which are the most important mineral constituent of soils. The articles in this book review the chemical reactions of feldspars over the whole sweep of pressure and temperature regimes in the outer Earth, and describe the fundamental aspects of crystal structure which underlie their properties. The book covers intracrystalline reactions, such as order-disorder transformations and exsolution, and transfer of stable and radiogenic isotopes, which can be interpreted to provide insights into the thermal history of rocks. It is suitable for final year undergraduates or research workers.

This book introduces the concept of crystallographic non- rigidity and asymmetry of the transition elements as central atoms organometallic compounds. This intrinsic behavior of central atoms in condensed matter is quantified by applying statistical approach. Averaging of extrinsic factors in crystal structures is tested by using variance analysis. Introductionof the above mentioned concept and applications of variance analysis as an approximation for considering factors influencing properties of central atomin the crystal is original and new.

Modeling and simulation were introduced to the earth sciences about four decades ago. Modeling has proven its worth and now it is an accepted procedure for analyzing and solving geological problems. The papers in this collection are focused on modeling sediment deposition and sedimentary sequences and have a decidedly practical flavor. Some of the leading simulation packages, such as CORRELATOR, SEDFLUX, SEDpak, SEDSIM, STRATA, and STRATSIM are applied to problems in hydrocarbon exploration, oil production, groundwater development, coal-bed appraisal, geothermics, and environmental diagnosis. All of these subjects fall under the broad heading of sedimentary basin analysis. The fifteen papers in this volume are written by internationally recognized experts from academia and industry. The contributions represent the status of geologic modeling and simulation at the start of the 21st century, and will give the reader an insight into current research problems and their possible solutions.

This book gives an account of a method of determining the type composition of sandy deposits from the air by the nature of their reflection of radiant energy. The measured spectral luminance of a rock outcrop rela ti ve to the luminance of a standard is the basic property considered in this method. The spectral luminance factors p\ are measured by means of special instruments - a universal photometer, cinespectrograph, spectro visors, and other spectrometers. The measured values of P" of the investigated rocks are interpreted geologically with the aid of some methods of mathematical statistics so that a means of lithological mapping of sandy deposits from the air can be found. The importance of developing a method of determining the type composition of rocks, primarily sandy de posits, from the air stems from the extensive occurrence of deserts on the earth's surface. Sandy deserts occupy vast areas in the southern latitudes of the USSR and occur in western and central China, Pakistan, Iran, India, and other states. In these deserts there are numerous deposits of petroleum and gas, and a search for water is continuously in progress. Successful prospecting for the above minerals depends on a determination of the material composition of the sandy deposits in these deserts and the solution of several questions of recent tec tonics, paleogeography, and quaternary geology, the answers to which might also be given by a study of the dis tribution of lithological types of sands.

This book presents the third volume of a complete development of the new structural classification of minerals, which is based on the internal crystal structure, and is therefore its natural classification. Because of the large domain of the mineral kingdom, this work is divided in three volumes, in which the minerals are ordered from the structurally simple to the more complex.

Audience: This work will be of particular interest to teachers and research workers of in mineralogy, and in inorganic crystal structures in academia.

Microbial defacement and degradation of artistic or historic artifacts is a worldwide problem affecting all countries regardless of their history, geographical location, or economic conditions. This is the first comprehensive study of the role of microbial colonization on the degradation of different cultural artifacts (from buildings to books, wall paintings, textiles, sculptures and glass) and of the investigations into the compounds utilized to control microbial invasion. The book focuses on three main areas: the identification of the microorganisms which cause structural damage; methods to reduce or prevent microbial colonization and damage; and the use of microorganisms for the protection and bioremediation of cultural artifacts.

Partial melting occurs in a variety of geological environments, from granitic partial melts in the continental crust, to basaltic or carbonate partial melts in the upper mantle. Partial melting is the first stage of magmatism and therefore plays a role of primary importance in the chemical differentiation of the Earth and in the transport of heat to the Earth surface. This special volume contains contributions presented at the symposium `Physics and Chemistry of Partially Molten Systems' of the EUG 9 meeting, held in Strasbourg, France, on March 23-27, 1997. It is intended to provide a current understanding of the physics of partial melting and melt segregation and covers topics such as the rheology of partially molten systems, the topology of partial melts, modelling of partial melting processes, and field observations of partial melts. Audience: This book is intended for a broad readership, including graduate students, specializing in petrology and geodynamics. The volume may be recommended as a textbook for graduate courses on petrology, geomaterial sciences and geophysics.

Basalt is the most voluminous of all the igneous rocks. Extensive field, experimental, petrographic and geochemical studies of basalt have provided us with a considerable understanding of igneous petrogenesis, plate tectonics, and crust-mantle interaction and exchange. One important aspect of geology that has developed over the last few decades is the study of oceanic basalts. The ocean basins cover about two thirds of the earth's surface and are floored by a basement of oceanic basalt that is continuously undergoing generation at spreading centres and destruction at subduction zones, a process which throughout geological time is recognized as the principal means of generating new crust. The study of oceanic basalts enables us to understand better the generation and recycling of crustal materials (including the continental crust), and the exchange between oceanic crust and seawater via hydrothermal activity. Compositional variations displayed by oceanic basalts provide windows into the mantle, and the identification of isotopically-distinct mantle reservoirs demonstrates that the source of oceanic basalts is heterogeneous and is controlled by convection and reservoir interactions within the mantle.

This volume illustrates some of the significant aspects of magmatic activity from Devonian (408 million years ago) to early Permian (270 million years ago) times in SW England. This period covers the progressive development of the Variscan mountain-building episode, from initial basin formation to final deformation and the subsequent development of a fold mountain belt - the Variscan Orogen. Both extrusive (volcanic) and intrusive (plutonic) rocks are found in the orogen, and chart the various stages of its magmatic development. The sites described in this volume are key localities selected for conservation because they are representative of the magmatic history of the orogen from initiation to stabilization. Some of the earliest volcanic activity in the Devonian is represented by submarine basaltic and rhyolitic lavas developed in subsiding basins, caused by the attenuation of the existing continental crust. In some cases, extensive rifting and attendant magmatism produced narrow zones of true oceanic crust, whereas elsewhere basaltic volcanism is related to fractures in the continental crust at the margins of the basins. After the filling of the sedimentary basins, and their deformation caused by crustal shortening (late Carboniferous Period), further activity is manifested by the emplacement of the Cornubian granites and later minor basaltic volcanism in the early Permian. Accounts of the constituent parts of this history have enriched geological literature from the nineteenth century onwards, and have contributed to the advancement and understanding of magmatic and tectonic processes.