Landforms and their Evolution

Landscapes (large tracts of the earth’s surface) are made by several related landforms together. Every landform has its particular physic, size, shape, and materials. A landform is formed as an outcome of the action of specific geomorphic processes and agents.

Every landform has a beginning, and through time, its shape and composition change. Landforms alter shape as a result of changes in climate and vertical and horizontal movement. Each landform goes through three stages: youth, maturity, and elderly. The science of landforms is known as geomorphology. Various geomorphic forces, including flowing water, moving ice, wind glaciers, subsurface water, and waves, affect landscapes via erosion and deposition.

Each geomorphological agent generates its unique set of landforms. The majority of geomorphological processes are undetectable. The study of landforms demonstrates that the stage structure and process of landforms are both important. They are responsible for erosional and depositional characteristics.

 Landforms

• It is a small to medium-sized part of the surface of the earth
• Geomorphic processes and agents may change the shape, size, and nature of landforms, either slowly or quickly
• Either the intensity of processes or the processes themselves might change due to climatic conditions and vertical or horizontal movements of landmasses. It leads to new modifications in the landforms
• Every landform has an initial phase and passes through a few stages of development, e.g., youth, mature and old age
  

• Erosional Landforms: Several erosional landforms, made by running water, are interconnected with energetic and juvenile rivers that flow over steep gradients. The stream channels over steep gradients turn gentle with time due to erosion and lose their velocity while allowing active deposition. 
• Depositional Landforms: The term is related to the streams flowing over lofty slopes. As compared to those interconnected with rivers flowing over medium to gentle slopes, this phenomenon will be on a small scale. The deposition will be greater in the more gentle river in gradient or slope.

The gentleness in stream beds due to continued erosion increased lateral erosion of banks. Downward cutting became less dominant. Subsequently, the hills and valleys were reduced to plains.

• The minor or significant quantities of materials from the surface of the land are removed due to shear friction of the column of flowing water in the flow direction, and gradually small and narrow rills are formed.
• These rills will gradually develop into long and wide gullies, which will further deepen, widen, lengthen, and unite to give a network of valleys.
• In the early stages, downcutting dominates, and irregularities such as waterfalls and cascades will be formed in that period.
• In the middle stages, lateral erosion of valley sides becomes severe, and their beds will be cut slowly by streams.
• Monad nocks are formed from some low resistant remnants with a faint lowland relief which is left behind from divides between drainage basins which are let down till the time it is completely flattened. The formation of this type of plain, as an outcome of stream erosion, is called a Peneplain (an almost plain).

Youth Stage

• In the Youth stage, few streams with poor integration flow over original slopes show shallow V-shaped valleys with no floodplains, or they come with very narrow floodplains
• Streams divide into broad and flat with marshes, swamps, and lakes
• Meanders, if present, develop over broad upland surfaces and may entrench into uplands
• Wherever local hard rock bodies are exposed, rapids, and waterfalls may exist.

Mature Stage

• At this stage, streams are plenty with better concatenation
• Valleys are V in shape with deep streams. The wide trunks have wider floodplains. Through these floodplains, streams can easily flow towards the zigzag confined within the valley
• At this stage, flat and wide areas meet the streams and wetlands of the youth disappear, and the division of streams becomes sharp
• Waterfalls and rapids disappear

Old Stage

• The smaller tributaries during the ageing period have a softer gradient
• Streams zigzag freely over the wide floodplains showing natural levees, oxbow lakes, etc
• Divides are wide and level with lakes, swamps, and marshes
• Most of the landscape is at sea level or marginally above sea level
• Valleys are V in shape. They have deep streams. The wide trunks have wider floodplains. Through these floodplains, streams can easily flow towards the valley while crossing the blocked road.

Conclusion

Geomorphic agents cause landscapes to alter after they have weathered. Landforms are small to medium-sized reactions or chunks of the earth’s surface. Landscape refers to a collection of landforms. Each landform is unique in terms of shape, size, and materials. Geomorphological processes are sluggish in the short run, but important in the long run.