Meeting of international specialists to compare and discuss data on ore deposits.

Sediment-hosted deposits are the main source of zinc and lead. In this volume, the reader will find the most recent developments in research including: - Fluid migration leading to formation of Zn-Pb ores in sedimentary basins. Relationships to orogenic events and to geothermic anomalies - Transport of metals and precipitation mechanisms. The role played by fluid mixing, fluid-rock reaction, organic matter, and thiosulfates - Paleomagnetic dating of ore deposits - The association of Mississippi Valley-type ore deposits to diapiric salt structures - Geochemical investigations applied to exploration for sediment-hosted Zn-Pb deposits - Economic aspects. The broad geographical coverage is an additional aspect which will interest both researchers and explorationists.

In 1963 the first Symposium on "Ores in Sediments" took place as part of an Inter national Sedimentological Congress. At the end of that first Symposium. the group then assembled adopted a resolution printed in the book which resulted from it (AM STUTZ. 1964, p. 7). and points (3). (4) and (5) read as follows: (3) The group considers the integration of sedimentology in any study of ore deposits in sediments essential to a correct interpretation. A study of the role of sedi mentary processes, including diagenesis, is an important field in pure as well as in applied research on the genesis of mineral deposits. (4) In particular. the group also considers the knowledge of sedimentary rocks and processes (in regard to both. the fabric and the geochemical detail) a prerequi site for the understanding of subsequent metamorphic processes and their pos sible role in the deformation and reconstitution of mineral deposits and host rocks. (5) The group suggests that similar symposia could with advantage be held at future Congresses of the International Association of Sedimentologists. The Editors wish to thank the International Association of Sedimentology for includ ing another Symposium on ore minerals in its Congress program.

reader who wishes to study economic mineral deposits. I have in mind that it they do include references to the source material. Full bibliographies are in could be the basic descriptive part of a university course on the subject. many cases unnecessary because of the monumental work of Ridge (Ridge, Many teachers of economic and mining geology prefer to lecture on the 1972 and 1976). formative geological processes and origin of mineral deposits, and most of The Scope, Purpose and Layout of the Book Terminology. This is a persistent problem in geology. What I have tried to the existing textbooks do likewise. The Atlas is intended to be a compen Air, sea, surface water and soil support life, from which comes our food; the dium of descriptive material on which a more analytical series of lectures, or do is use a consistent, and internationally acceptable set of terms, making as much use as possible of the recent attempts by international organizations to fossil remains of life, that is: coal, oil and gas, together with solar and course of reading, could be based.