This book is primarily intended to assist candidates studying geology for the Ordinary Level of G.c.E., and examinations of comparable standard, but it should also be found useful by the reader requiring a rapid conspectus of the geological history of Britain, and as forming a basis for more advanced work. The scope of the subject matter necessitated a narrow and slippery path be tween over-simplification and excessive detail, but the balance adopted is based upon the experience of many years of teaching at all levels, and of examining for the London G.C.E. Board. The maps, combining outcrop dis tribution with palaeogeography, presented some difficulty, especially for periods of continuously changing geography, such as the Cretaceous. It was necessary in these cases to make an arbitrary choice of one small part of the period, the geography of which could be illustrated. Candidates are advised not to spend time learning every detail of the outcrop patterns, but to con centrate upon the main areas of outcrop. I am indebted to Mrs. Jean Fyffe for the cartographic work.