a)A Davisian idea
b) The point to which a landform has evolved during a cycle of erosion
c) As a result of the different processes the land forms pass through different stages – a series of orderly and sequential changes.
Drainage refers to the movement of water (from rainfall and snowmelt) either over Earth’s surface or down into the soil and bedrock.
Although moving water is an outstanding force under the ‘process’ heading, the ramifications of slope wash, stream flow, stream patterns, and other aspects of drainage are so significant that generally the topic or drainage is considered a basic element in landform analysis.
An inclined surface, the gradient of which is determined by the amount of the inclination from the horizontal, and the length of which is determined by the inclined distance between its crest and its foot. A slope may be concave, straight or convex when seen in profile.
Usually, most of the topographic details have been produced during the current cycle of erosion, but there may exist within an area remnants of features produced during prior cycles, and, although thee are many individual landforms which can be said to be the product of some single geomorphic process.
Horberg (1952) classified landforms into five major categories:
5. exhumed or resurrected landscapes
Simple landscapes are the product of a single dominant geomorphic process.
Compound landscapes are those in which two or more geomorphic processes have played major roles in the development of the existing topography.
Monocyclic landscapes have been produced during more than one cycle of erosion. Monocyclic landscapes are less common than multicyclic and are in general restricted to such newly created land surfaces as a recently uplifted portion of the ocean floor, the surface of a volcanic cone, lava plain or plateau, or areas buried beneath a cover of Pleistocene glacial deposits.
It has become evident in recent years that many landscapes have evolved under more than one set of climatic conditions with accompanying variation in the dominant geomorphic processes. Many of these varying climatic conditions were associated with the fluctuating climates of Pleistocene time, but are some areas certain aspects of the topography reflect climatic conditions that existed during Tertiary times.
Exhumed or resurrected landscapes
are those which were formed during some past period of geologic time, then buried beneath a cover of igneous or sedimentary origin, then still later exposed through removal of the cover. Topographic features now being exhumed may date back as far as the Precambrian or they may be as recent as the Pleistocene.