Day 84 – Q 3. With the help of suitable examples, explain the correlation between landform evolution and geophysical phenomena.

3. With the help of suitable examples, explain the correlation between landform evolution and geophysical phenomena.  

उपयुक्त उदाहरणों की मदद से, भूनिर्माण विकास और भूभौतिकीय घटना के बीच संबंध को समझाएं।

Introduction:

Landform evolution is an important aspect of earth sciences and involves complicated interaction among different physical processes and environmental factors, such as underlying rock structures, tectonics, rock types, climate and climatic changes, and human activities, all occurring over a wide range of spatial and temporal scales.  

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Correlation between landform evolution and geophysical phenomena 

• One of the most commonly observed patterns of river systems is the branching pattern of dendritic drainage network (from the Greek dendrites). It ranges from the small scale of rill (formed by erosion on a newly exposed surface) to the continental scale drainages that evolved over long geological times (e.g., the Mississippi, the Amazon, the Congo, and the Yellow).
• Climatic variables play a key role in drainage form, slope form and process, and in the evolution of a drainage basin through time. Annual variations in temperature, precipitation, and seasonality of precipitation work together to influence the degree of chemical and physical weathering of slope materials, the depth of weathered materials or soils that develop, and perhaps most importantly, to determine the vegetation type and percentage of cover across a landscape. 
• Vegetation covers in turn controls slope form and mass movement process and therefore the resultant drainage basin attributes.
• In temperate regions, the rates of chemical and/or physical weathering are sufficiently high to produce thicker sequences of weathered materials or soils that often bury rock outcrops in their own weathering products. 
• Vegetation cover is high, protecting the surface from rain splash and the root mass is sufficient to stabilize the materials on the slope. When overland flow does occur it is often ineffective at eroding the surface because of the protective vegetation, and infiltrating waters moving downslope as “throughflow” are prevented from eroding the soil because of the binding effects of plant roots.
• In the temperate climate landscape, downslope movement of materials to the fluvial channel occurs primarily by the slow mass movement process of either continuous or seasonal creep. Longitudinal profiles for these “creep dominated slopes” assume a smooth convex/concave form from the drainage divide downward to the stream channel.
• The wind is the main geomorphic agent in the hot deserts. The landforms which are created by erosional and depositional activities of wind are called as Aeolian Landforms.
• Volcanic eruptions result in the formation of landforms- intrusive and extrusive landforms. 
• Glaciers have played an important role in the moulding of landscapes in the mid and high latitudes of alpine environments. The major depositional landforms made by glaciers are – Esker; Outwash plains; Drumlins.

Conclusion

The geophysical phenomena keep changing the landforms with varying degree.