This book, first published in 1985, is a dramatic revision of Dr. Allen’s earlier book. Completely restructured, more comprehensive and more concerned with fundamental physical principles. It is intended for the senior undergraduate and beginning postgraduate student in Earth Science. It covers general physic in order to understand the small scale mechanically formed features of detrital sediments. The coverage is very thorough and the ideas are presented in a lively text written in an interrogative style which constantly poses questions to the reader and suggests lines of enquiry. The text is widely illustrated. Highlights include the exceptionally thorough introduction to the basic physical principles of sedimentation and the lively and varied accounts of flow in meandering channels and turbulence. Terra Cognita I was unable to read more than a few pages without encountering some new and stimulating idea. Does not resemble any other sedimentology textbook. The great strength of this book, as of much of Allen’s other work, is in applying physical reasoning and simplified mathematical modelling to sedimentologic problems. Allen here reminds me of Bagnold: Both have performed highly original and seminal analyses. Sedimentology