Geomorphy

Geological doctrine of modern origin, whose fundamental principle emphasizes the action of rivers and streams in shaping the earth's surface. It teaches that river erosion, immediately on the emergence of the land, begins the proce of again degrading it to sea-level, and that this proce continues, unle interrupted by re-elevation, until the whole surface is reduced to the sea-level. On this principle physical geography recognizes the youthful period of a river when it flows in a canyon, the middle-aged period when the canyon has become an open valley, and the senile period when the country has become almost flat and the river has nearly ceased to flow. The relief of the surface thus supplies a clew to its age: the study of this relief as it exists at present, and the investigation of its past history and the important consequent changes of drainage, are some of the problems pre sented. Geomori. Rural nobles of A then i an empire. Geomydæ. See MYOMORPHA.