This Special Publication combines results obtained by interdisciplinary groups from numerous academic institutions working on Paleoproterozoic formations to decipher the origins of the main mineralization resources in the West African Craton (WAC) and their impacts on African economic development. Structural, geophysical, sedimentological, stratigraphical, geochemical, petrophysical and mineralogical analyses have been used to highlight the complexities involved in mineralization emplacement and its origin and evolution within the WAC. Fourteen articles contribute to new knowledge in mineral research. They show that the geodynamic evolution of the WAC is complex from one area to another: it involves subduction, collision and obduction during several deformation phases ranging from Birimian (2.3–2.0 Ga) to Pan-African (650–450 Ma) events. Various modelling techniques, when integrated, help in understanding the mechanisms of mineralization emplacement, some of which are still a matter of debate. The challenge for further studies is mitigation for sustainable development that can be appropriately used to minimize such damage.

Attention to the problems posed by natural hazards in West and Central Africa was brought into sharp focus by the deaths of an estimated 1700 people in the valleys to the north of Lake Nyos in 1986. Prior to that the only, well documented, major natural catastrophe was the 1983 earthquake which killed at least 275 people in northwestern Guinea. Though we would not wish to appear to suggest that the 1939 Accra earthquake, which killed 16 people, or the Lake Monoun disaster, which killed 37 people in 1984, were not significant events for the areas concerned. The full horror of the Lake Nyos gas disaster was exacerbated, as far as the outside world was concerned, by initial uncertainty concerning its cause. During the first phase of the investigation there were considerable disagreements between some of the participating groups of scientists. Many of these disagreements have now been resolved and it is to be hoped that the contributions in this volume will further help to resolve some of the outstanding uncertainties. However, although it is important to understand what happened at Lake Nyos in 1986, and why it happened, it is more important for the future of that area that further similar disasters should be avoided. We can only hope that this volume will help to establish a solid foundation for future research into ways of removing excess gas from the lake.

Morocco is one of the most fascinating lands in the world from the point of view of its geological structure and evolution. Our knowledge on the geology of the country has been greatly improved during the last decades, based on numerous seismic profiles and boreholes, seismological analysis of focal mechanisms, seismic tomography, gravimetric/geodetic modelling and, on the other hand, based on a big National Program of Geological Mapping including modern geochemical analyses (trace elements) and reliable isotopic datings (39Ar-40Ar, U-Pb zircon, Sm-Nd, etc). Moreover, a number of academic studies have been performed in relation with the increasing number of Moroccan universities. Accordingly, there was an utmost urgency to undertake a new treatise of Moroccan geology which could substitute for the classical Eléments de géologie marocaine, published in 1976 by A. Michard in the Notes et Mémoires du Service géologique du Maroc (re-edited twice since 1976, with more than 6000 copies sold, and... translated in Japanese for engineers!). A new treatise has been prepared between April 2006 and July 2007 under the coordination of A. Michard, assisted by O. Saddiqi, and A. Chalouan, by a wide panel of authors from Morocco, France or Belgium among the best connoisseurs of the country. In order to emphasize the general interest of the book, we finally retain the following title: Continental Evolution: The Geology of Morocco. Structure, Stratigraphy, and Tectonics of the Africa-Atlantic-Mediterranean Triple junction. The editing and production of this book was supported by the following organisations: The Geological Society of France (SGF) The National Office of Hydrocarbons and Mines of Morocco (ONHYM) The International Lithosphere Program (ILP)

T is atlas is intended primarily for anybody who is in-some background for the arrangement of how the terested in basic geology of Africa. Its originality lies atlas was done. T e second chapter is devoted to the in the fact that the regional geology of each African history of geological mapping in Africa, necessary nation or territory is reviewed country-wise by maps for a fuller appreciation of why this work in Africa is and text, a view normally not presented in textbooks worth doing. Chapter 3 provides an executive s- of regional geology. It is my belief, that there has long mary on the stratigraphy and tectonics of Africa as a been a need in universities and geological surveys, whole, i. e. in the context of no political boundaries. both in Africa and in the developed world, for sum- T e main part of the atlas lies in Chapter 4, where in marizing geological maps and an accompanying basic alphabetical order each African country or territory text utilising the enormous fund of knowledge that is presented by a digitized geological overview map has been accumulated since the beginning of geologi- and an accompanying text on its respective strat- th cal research in Africa in the mid-19 century. I hope raphy, tectonics, economic geology, geohazards and that, in part, the present atlas may satisfy this need. geosites. A short list of relevant references is also a- ed.

In this text, attention is focused mainly on those literature is accessible, however, it is to be expected countries in western Africa lying south of the Sahara, that teachers and lecturers will know of it and will be that is, between about SON and 15°N, and westward able to acquaint their students with it, where neces of about 15°E. Parts of the region as far north as sary. about 200N are considered from time to time, for A glossary of terms is provided at the end of the purposes of correlation and cQntinuity. The map on volume, and there is a summary at the beginning of p. xiii indicates the approximate extent of the cover each chapter. age. This book is dedicated to the many colleagues and The principal aim is to provide a broad view of students with whom we have worked in West Africa West African geology as a whole, for undergraduates and who have stimulated and encouraged our teach who are studying for honours degrees in geology and ing and research in various ways. We hope also that it may help the work of international organizations who already have an understanding of basic geologi cal principles. It is increasingly important that such as AGID, CIFEG and UNESCO to encourage the growing trend towards geological co-operation geologists working in this region should see it as made up of geological 'provinces' which transcend and correlation between different countries in West national boundaries. Africa.

Africa is highly vulnerable to the impacts of climate change. In particular shortage of fresh water is expected to be the dominant water problem for West and Northwest Africa of the 21th century. In order to solve present and projected future problems concerning fresh water supply, a highly interdisciplinary approach is used in the book. Strategies are offered for a sustainable and future-oriented water management. Based on different scenarios, a range of management options is suggested with the aid of Information Systems and Spatial Decision Support Systems for two river catchments in Northwest and West Africa: the wadi Drâa in south-eastern Morocco and the Ouémé basin in Benin. The selected catchments are representative in the sense: "what can be learnt from these catchments for other similar catchments?