Advances in Organic Geochemistry 1968, Volume 31 contains the proceedings of the 4th International Meeting on Organic Geochemistry, held in Amsterdam, Netherlands, on September 16-18, 1968. The papers explore advances in several fields of organic geochemistry, including organic compounds found in sediments, geochemistry of coal and petroleum, and organic geochemistry of the oceans. This book is comprised of 39 chapters and begins with a discussion on the distribution of hydrocarbons and fatty acids in living organisms and in sediments, paying particular attention to biological markers and the carbon skeleton concept. The reader is methodically introduced to the mechanisms of formation of petroleum from sediment organic matter; dissolved organic matter in the oceans; the fatty acid content of tasmanites; and identification of steranes and triterpanes from a geological source using capillary gas liquid chromatography and mass spectrometry. The chemistry of coal and crude oil metamorphism is also considered, along with the racemization of amino acids on silicates. The final chapter focuses on carbon polytypism in meteorites. This volume will be useful to organic chemists, geochemists, and all those interested in the field of organic geochemistry.