This is the English translation (and German facsimile) of Wladimir Köppen and Alfred Wegener (1924): The Climates of the Geological Past (Die Klimate der geologischen Vorzeit), a landmark text of early paleoclimatological research, actually a textbook of paleoclimatology. Wegener is best known for his theory of continental drift (The Origin of the Continents and Oceans, 1915). Less widely known, but equally important, are the studies he conducted on the climates of the past (with his colleague and father-in-law, Wladimir Köppen), which they jointly published (this book). Only one edition of the book was published, but unfortunately, all - save a few private copies - were destroyed during the second World War, rendering the book essentially unavailable. This English translation makes Köppen and Wegener's landmark text accessible to the international climate research community. It also includes the Supplements and Corrections by ­Wladimir Köppen to this book, published in 1940, shortly before his death and a decade after Alfred Wegener's untimely death on Greenland. The translation (and the facsimile) have both been enhanced by subject indices, which the original book was lacking. The discussion of the course and causal relationship of climates and climate change in the geological past are of principal scientific interest. Important elements of the discussions herein stem from the close collaboration with Milutin Milankovitch (who contributed entire sections of text, but is not named as an author). Building on the principles of the Milankovitch frequencies allowed Köppen and Wegener for the first time, early in the last century to establish a precise time scale of Late Cenozoic glacial-inter­glacial cycles. More recently, the orbital parameters originally calculated by Milankovitch were refined using time series data from deep-sea sediments and ice cores. Furthermore, Milankovitch's cycles may be extrapolated into the future to predict climate change. This very book, in which Köppen and Wegener roll out their theory, is therefore an important publication which has early on shaped our understanding of how climate has evolved and continuously evolves in the course of time. This translation affords non-German-speaking scientists and laypersons alike access to the full and compelling arguments of climate change, carefully and readably laid out and argued. It is a must-read for anybody interested in climate change, be it from a historic or present point of view.