Intended as a supplement to undergraduate college geography courses, this resource paper describes the science of geomorphology, the study of landforms. The general aim of this paper is to review the developments which have made geomorphology what it is today, to indicate its present character and status, to demonstrate its increasingly close linkages with other types of study, and to suggest ways in which it is likely to develop further in the near future. This survey describes the various theories and concepts of geomorphology which have been prevalent in the twentieth century. Climatic factors are related to the distinctive arrays of geomorphological processes and resulting landforms. The continental drift hypothesis is discussed in relation to the process known as sea-floor spreading, the expansion of the ocean floors under the influence of convection currents in the earth's interior. Also described are the new developments in statistical geomorphology, which depend on probability analysis and produce probability models. The increased use of quantification, statistical analysis, and mathematization is seen as a promise to unify geomorphology with the rest of the natural and physical sciences. (Author/MLH)