GEOMORPHOLOGICAL EVENTS AND LANDFORM CHANGE - THE CENTENARY LECTURE TO THE DEPARTMENT OF GEOGRAPHY, UNIVERSITY-OF-HEIDELBERG

'':The true science of geomorphology did not begin until revolution wa s replaced by gradual development or evolution, consisting not of migh ty, unknown natural events but of the summation of processes daily ope rating before our eyes. Precursors of this actualist approach are the two Frenchmen, GUETTARD and DEMAREST, the Scots, HUTTON and PLAYFAIR, and the Thuringians, HEIM and VON HOFF. But CHARLES LYELL first brough t it into general currency, and for this reason he has considerable im portance for geomorphology, even though he exaggerated the effect of t he sea, and underestimated valley formation to an inhibiting degree. T ruly scientific approaches and theories are possible only on the basis of actualistic and evolutionary theory.:''