This is the second edition of the author's account of celebrated controversies in geology that embrace many of the most important ideas that have emerged since the birth of the subject. Two new chapters have been added. One reviews the emergence of stratigraphy in the nineteenth century, focusing on two major controversies concerning the Cambrian-Silurian and the Devonian. The second new chapter deals with the mass extinctions controversy, which has not yet been resolved. The existing chapters have been revised in the light of recent publications. The book will be of interest to professional geologists, geology students, and amateur geologists as well as to geographers and historians of science.