Cycle of Erosion By L.C. King
L.C.King or Lester Charles King was a South African Geomorphologist. He explained the evolution of south African landscape through a cycle of erosion. He stared his study over the arid, semi arid and savana region of south Africa. This region is characterised by extensive plain area along with some uplifted landscape, scarp and eroded place, which he has given name as Pediplanation.
Pediplanation refers to the remarkable surfaces of planation, surrounded by isolated hills and piles of boulders. Thus, L.C.King proposed an entirely new theory as cyclic model of pediplanation in the year of 1948.
King’s observation: After extensive study of south African landscape he came to this point that African landscape comprises of three elements.
- Rock pediments, flanking river valley and having concave slope with varying angle from 1.5 degree to 7 degree.
- Scarps having steep slope of varying angle from 15 degree to 30 degree.
- The steep sided residual hills known as Inselberge or bornhardts with varying shape and size.
The cycle of pediplanation of L.C.King performed by twin processes i.e scrape retreat and pedimentation. The cycle of pediplanation passes through three stages – youth, mature and old stage.
Youth stage: This stage is characterised by upliftment of the landscape. Thus, the river started rapid down cutting that also given birth lots of gorge and canyons. Knick point is another remarkable sfeature in this stage cause by changes of slope gradient. But with the march of time down cutting goes slow down and small pediments will begin to appear at the bottom of the valley.
Mature stage: This stage is characterised by active lateral erosion, downcutting or vertical erosion totally stop. Due to lateral erosion the interfluve area become narrowed down, after some time it turn into a steep sided rounded top like feature, called as Inselberge. Active lateral erosion is also cause for valley retreating. Thus, valley sides are distanced from the channel, but significant change in slope can not found. Many of inselberges are losing its height due to lateral erosion and weathering, thus it turns into castle koppies. After sometime these castle koppies also started to disappear due to extension of pediment. These pediments also coalesce with othe pediments to form extensive flat plain, called as pediplain. These pediplain is charactyerised by undulated surface with low relief, concave slope and few remnants of inselberge and castle koppies.
Old stage: This stage is characterised by disappearance of residual hills. The entire landscape became a flat extensive low angled pediments.
Evaluation: king’s geomorphic theory could not received as much support that he deserved because of some assumptions of his model was controversial. Another reason was, at that time most of the geomorphologists were least interested about geomorphic theories as they were busy in quantifying landforms, data obtained through field instruments, laboratory experiments which take vary short time and smaller spatial scales.
Please read Cycle of Erosion By Penck – https://smoothknowledge.com/2019/06/14/cycle-of-erosion-by-penck/