This 1962 book is a concise study of one of the most important and complex parts of the geological succession, the middle part of the Tertiary Era, in which sediments of great economic importance (especially for the petroleum and related industries) were deposited. The authors have examined the relevant stratigraphy of New Zealand, Australasia, Oceania, Indonesia, South East Asia, the Indian subcontinent, Middle East, East Africa, North Africa and the Mediterranean, the classical successions of Europe and the detailed successions of the Central American region, incorporating the expert opinion of other geologists and including much previously unpublished work by themselves and their colleagues; in particular, Dr L. R. Cox has contributed a section on the Oligocene and Aquitanian marine molluscan faunas of parts of Europe. Much of the information is presented graphically and a comprehensive description of the true Oligocene plantonic stratigraphical index foraminifera is given.