Landforms and Their Evolution
Landforms and Their Evolution: Landforms are mainly created by endogenic or exogenic forces. For example landforms are created by running water, wind action, glacier, volcanism etc. Landforms are the results of erosional or depositional processes.
- Cirque, moraine, arete, ‘U’ shape valley, drumlin, esker, outwash plain etc. are the glacier made landforms.
- ‘V’ shape valley, waterfall, alluvial cone, meander, ox-bow lake, cliff, slip of slope, and shoal etc. river made landforms.
- Mushroom rock, pediment, sand dunes, barchan, etc. are wind action made landforms.
- There are basically two types of running water actions are responsible for the creation of different landforms. Surface flow and flow through the particular channel.
- Basically main erosional landforms are created by vigorous and youthful river channel.
- There three stages of the river creating different types of landforms. like, Young stage, mature stage and old stage.
- ‘V’ shape valley is the main landform created in the young stage due to the steep slope and vertical erosional process of the river.
- Due to the structural reason, means due to the location of hard rock on the way of the river, some times waterfall may be formed in the young stage.
- Erosion is the main characteristics of the young stage.
- In the mature stage ‘V’ shape valley may present, but gradually start to flattened due to lateral erosion.
- In the mature stage meandering river flow is common features.
- Waterfall or rapids are gradually disappear in this stage.
Braided channels are common in old stage.
- All erosional activities are disappeared in old stage. Here all landforms are depositional in old stage.
- Delta formation at the region of mouth of the river come under this old stage.
- Pothole means circular shape depression created by abrasion of rock fragments.
- Plungepools means a large and deep holes formation at the base of the waterfall.
- Incised or entrenched meander mainly forms due to the rejuvenation of the river. Due to the upliftment of the upper course of the river or suddenly depression in the lower course of the river rejuvenation occurred.
- Due to the rejuvenation of the river, when river again start to erode the meandering part of the river, the depth of the river on the meandering part increase. The newly landforms creates ‘valley in valley’ in the meandering part which means entrenched meander.
- River terraces are mainly created by the process of rejuvenation of the river.
- Alluvial fan: forms due to the deposition of erosional materials on the breaking point of the slope. 62