Key Points

Geomorphic processes are the endogenic (internal) and exogenic (external) forces that cause physical stresses and chemical actions on earth materials, leading to changes in the surface configuration.

Endogenic forces originate from within the earth, building up the crust (e.g., volcanism), while exogenic forces originate from the atmosphere, wearing down the surface (e.g., erosion).

Diastrophism is an endogenic process that moves, elevates, or builds up portions of the crust. It includes orogeny (mountain building) and epeirogeny (continent building).

Exogenic processes derive their energy from the sun and are collectively known as denudation, which means to strip off or uncover. This includes weathering, mass wasting, erosion, and transportation.

Weathering is the in-situ (on-site) mechanical disintegration and chemical decomposition of rocks by elements of weather and climate. It involves very little or no movement of the resulting material.

Weathering is categorized into three types: chemical (decomposition by reactions), physical or mechanical (disintegration by applied forces like temperature change), and biological (actions of organisms).

Weathering is crucial as it breaks down rocks, preparing the way for soil formation and aiding mass movements and erosion. It also helps in the enrichment of valuable mineral ores.

Mass movements involve the transfer of rock debris down slopes under the direct influence of gravity. Unlike erosion, geomorphic agents like water or ice do not carry the debris.

Landslides are rapid and perceptible mass movements of relatively dry materials. Common types include slump (with backward rotation), debris slide, rockslide, and rockfall.

Erosion is the acquisition and transportation of rock debris by geomorphic agents like running water, groundwater, glaciers, wind, and waves. It is a degradational process that wears down the landscape.

Deposition is the settling of materials carried by erosional agents. It occurs when the agent loses energy, typically on gentler slopes, and results in the filling of depressions.

Soil formation, or pedogenesis, is the process of soil development that begins with the weathering of parent material. This weathered mantle is then colonized by organisms, leading to the accumulation of humus and the formation of a mature soil profile.

The formation of soils is controlled by five key factors acting in union: parent material, topography, climate, biological activity, and time.

Parent material (the rock debris) and topography (the shape of the land) are considered passive control factors. They determine the texture of soil and influence drainage and soil thickness.

Climate is an important active factor, where precipitation provides moisture for chemical and biological activities, and temperature influences the rate of these activities.

Biological activity is another active factor where plants provide humus (organic matter) and organisms like bacteria help in nitrogen fixation. Burrowing animals also mix and aerate the soil.