The history of the earth includes among many things an account of its structure and form at successive times, of the processes by which changes in its structure and form have been produced, and of the causes of these processes. Geography is according to ordinary definition allowed of all this only an account of the present form of the earth, while geology takes all the rest, and it is too generally the case that even the present form of the earth is insufficiently examined by geographers. Geographic morphology, or topography, is not yet developed into a science. Some writers seem to think it a division of geology, while geologists are as a rule too much occupied with other matters to give it the attention it deserves. It is not worth while to embarrass one's study by too much definition of its subdivisions, but it is clearly advisable in this case to take such steps as shall hasten a critical and minute examination of the form of the earth's surface by geographers, and to this end it may serve a useful purpose to enlarge the limited definition of geography, as given above, and insist that it shall include not only a descriptive and statistical account of the present surface of the earth, but also a systematic classification of the features of the earth's surface, viewed as the results of certain processes, acting for various periods, at different ages, on divers structures. As Mackinder of Oxford has recently expressed it, geography is the study of the present in the light of the past. When thus conceived it forms a fitting complement to geology, which, as defined by the same author, is the study of the past in the light of the present. The studies are inseparable and up to a certain point, their physical aspects may be well followed together, under such a name as physiography. Specialization may then lead the student more to one subject than to the other.
An illustration from human history, where the study of the past and present has a single name, may serve to make my meaning clear in regard to the relation of the two parts of terrestrial history, which have different names. A descriptive and statistical account of a people as at present existing, such as that which our statistical atlas of the last Census gives in outline, corresponds to geography in its ordinary limitation. A reasonable extension of such an account, introducing a consideration of antecedent conditions and events, for the purpose of throwing light on existing relations, represents an expanded conception of geography. The minute study of the rise and present condition of any single industry would correspond to the monographic account of the development of any simple group of geographic forms. On the other hand, history taken in its more general aspects, including an inquiry into the causes and processes of the rise and fall of ancient nations, answers to geology; and an account of some brief past stage of history is the equivalent of paleography, a subject at present very little studied and seemingly destined always to escape sharp determination. It is manifest that geology and geography thus defined are parts of a single great subject, and must not be considered independently.