Deposition of sediments on either side of the river valleys leads to the formation of natural levees.The old stage is characterized by further decrease in channel gradient, almost total absence of valley deepening, decrease in the number of tributary streams and flattening of valleys.
In this article we will discuss about the meaning and stages of ‘normal cycle of erosion’.The cycle of erosion by fluvial processes (running waters or rivers) is called normal cycle of erosion because of the fact that fluvial processes are most widespread (covering most parts of the globe) and most significant geomorphic agent. Even water also plays important roles in glacial, and arid regions. The interruptions caused by negative changes in base level (lowering of base level-maximum limit of vertical erosion by rivers) due to fall in sea level (because of the subsidence of the oceanic floors) and upliftment of landmass are called rejuvenation, which means renewed vigour of erosive capacity of the rivers.Rejuvenated rivers are again engaged in valley deepening at much faster rate and thus the cycle of erosion is driven back to youthful (juvenile) stage. Thus, the smooth functioning and completion of normal cycle of erosion is very often disturbed due to tectonic events and also due to climatic changes.The disturbance in the cycle of erosion is called interruption of normal cycle of erosion which is caused by changes in sea level (either due to upliftment or subsidence of oceanic bottoms or due to glaciation and deglaciation during great ice ages, like Carboniferous glaciation of the Gondwanaland during Carboniferous period and Pleistocene glaciation of the northern hemisphere during Pleistocene period), upliftment or subsidence of land areas, volcanic eruptions and climatic changes.The interruption of normal cycle of erosion by volcanic eruptions or climatic changes is called ‘accident’. The slopes are dominated by numerous rills and gullies rather than big streams.These rills and gullies lengthen their longitudinal profiles (increase their lengths) through headward erosion. Tributary streams also attain the base level of erosion and are graded. The major river erodes down to its base level (sea level) and becomes ‘graded’.Thus, the longitudinal profile of the master river becomes the profile of equilibrium wherein there is balance between available energy and the work to be done i.e., balance between the transporting capacity and total sediment load to be transported. Valleys become broad and flat characterized by concave slopes of valley sides.Downcutting of the valleys is totally absent. The bed and banks can be eroded making it wider, deeper and longer.Headward erosion makes a river longer.
Rivers deposit and form extensive deltas at their mouths if other environmental conditions remain favourable for delta formation.The entire landscape is converted into extensive flat plain of undulating surface except a few residual convexo-concave hills which project above the general flat surface and thus break the monotony of reliefless flat plain, called as peneplain. The landmass may, at some later time, be rejuvenated and the cycle begins again and remnants of the earlier cycle of erosion are preserved at new and higher levels.In a normal cycle three stages have been recognized as: youth stage, mature stage and old stage.
The rate of uplift in the beginning far exceeds the rate of erosion with the result absolute relief (absolute altitude from sea level) and relative relief register increase.After some time upliftment of the land stops and erosion becomes more active. Davis’ Stages in the fluvial cycle of erosion published in 1909 defined a young, mature, and old sequence in the development of river valleys and the landscape the rivers were eroding. As the land rises, the rivers are originated and their erosional work starts.
New Air Force One Design, Jason Peters Stats, Wipeout Season 3 Episode 15, Danish Restaurants Near Me, Nj American Water Login, Oregon Unemployment Department Phone Number, Monster Prom 2 Trailer, Bulbulay Season 2 Episode 45, Tyler, The Creator Funny Quotes, Irwin Tool Kit, San Jose Online News, Kobe Bryant Attributes, Ex On The Beach: Peak Of Love 123movies, School Border Template, Blue Water Font, Kd Number 1 Prabhakar, How Does Wind Move, Serendipity 3 $1,000 Sundae, Mahesh Thakur Parents, Commentary Words List, Jefferson College Soccer, Very Resistant Synonym, Peyton Williams Instagram, Coh Share Price,