Studies of the Jurassic period are greatly helped by the high degree of stratigraphic control provided by the ubiquitous ammonites. Although this work, originally publisjed in 1975, is not a study of stratigraphy as such, a short chapter on this topic is included to provide a framework for environmental interpretation. The main goal of this book is to review in detail the advances which existed at the time in the interpretation of Jurassic facies in the classical European and American deposits and to then apply this knowledge to illuminate more general topics such as the fluctuation in land/sea distribution and the nature of the Jurassic climate and biogeography. There is also an account of plate tectonics and igneous activity during the period. A comprehensive bibliography is provided, which includes the important stratigraphic literature published from 1956 to 1975.