Lester Charles King's Models of landscape evolution and slope development

1. KING’S MODEL OF LANSCAPE
EVOLUTION AND SLOPE
DEVELOPMENT
BY: Charu Jaiswal

2. Geomorphogenesis ("land" + "form" + "origin") is controlled in many way by many different
factors. Some of the processes operate at the Earth's surface, others work in the subsurface.
 Most surficial processes (except sediment deposition) degrade the landscape (i.e. wear it
down) whereas most internal processes contribute in some way to building up (aggrades) the
surface.
 So in a sense, external forces battle internal forces for control of the appearance of the
Earth!!!
The end result is a landform.

3. INTRODUCTION
 The larger task of endogenetic forces is to create irregularities on the
surface of the Earth by volcanism, mountain building, etc. As soon as
these end forms are exposed on the, the various processes of
weathering start working on them. Soon these are weathered, and in
due course of time, the weathered products are transported by Various
agents. The whole period, during which erosion processes erode the
new surface to sea level is one cycle and since erosion plays an
important part in it, it is called the cycle of erosion.
 The significance of the cycle concept is that it explains the sequential
development of Landforms in a temporal framework.
 There are three views on the cycle of erosion. These are of Davis,
Penck and King.
 These views relate to the sequential development of landforms in an
orderly fashion during which the slope also evolves in a variety of
ways. Thus, these cycles, while describing the development of
landforms, also give information about the evolution of slopes.

4. LESTER CHARLES KING
Lester Charles King (1907 – 1989) was an English
geologist and geomorphologist known for his theories
on scarp retreat.
Kings ideas are contained in his 2 books:-
1) Morphology of the earth (published in 1960 )
2)Cannons of landscape evolution (1953)
Kings received his training from C.A Cotton in Davision
morphology ,T.J.D Fair for the ideas of slope and Alex L.
Du Toit for ideas on tectonics.
Kings ideas are influenced by his observations in
southern Africa.
His ideas included some components from the model of
davis and penck. He rejected some of these and
introduced some completely new ideas.

5. • He rejected the relationship between uplift and slope formed by
penck.He accepted the idea of structure- process and slope given
by Davis but he changed the sequence in which process was
placed first.
• Process for king meant the semi-arid enviornment.The semi-arid
environment was suggested by king because in this type different
types of river mass wasting and weathering process are
important in addition to the work of river.
• His ideas represent a combination of Process, structure ,crustal
movement and mass wasting.
Kings idea can be understood in terms of 3
components:
1) Slope element
2)Development of Hill slope
3)Epigene cycle of erosion

6. SLOPE ELEMENTS
King used four slope elements which
were initially proposed by ‘wood'. Each
element is semi-independent. Any one
of the elements can be completely
absent on a given slope. This is
particularly true for free face.
1) Waxing slope: It is a convex segment
at he crest of the slope. It is covered by
weathered material. Transportation on
the surface is dominated by soil creep.
2) Free face: It is similar to cliff
proposed by Penck.It is a bedrock out
creep which retreats parallel to itself
under the influence of weathering
processes and uniform removal of
material. However areas which do not
have enough large relative relief ,free
face may not develop.

7. 3)Debris slope: Its
development is
dependent upon free
face. If free face is
there, debris slope will
be there and vice-versa.
4)Waning slope: It has
a gentle concave
profile. There may be
bedrock or transported
material covering
eroded bed rock
surface, when the
eroded transported
debris cover such a
surface it is known as
pediment.

9. WHAT IS PARALEL RETREAT ?
Each of the upper parts of the slope retreats by the same amount and maintain the
same angle .
Therefore, the convexity, free face and debris slope all retain the same length.
The concavity extends in length and becomes slightly gentler in angle. This is called
pediment
This type of evolution is called a parallel retreat.

10. WHAT IS PEDIPLANATION ?
• He envisaged the parallel retreat of a single free face
slope unit, leaving a broad, concave pediments
sloping at an angle of 6-7 degree or less at its base.
Gradually over time, pediments coalesce to form
pediplains and this mode of landscape development,
is therefore called pediplanation.

11. DEVELOPMENT OF HILL SLOPES
• King rejected the climatic basis of landscape development and
suggested that all landscapes are basically similar.
• He featured semi-arid climate as normal climate because acc.to
him high proportion of earth surface have this type of climate and
it has been dominant climate throughout the geological history of
the earth.
• He accepted the division of tectonics movements by penck i.e.
orogeny, epeirogeny and cymatogeny.
• Pedimentation was proposed as a basic process in hill slope
development by king.
• Parallel retreat of slope results in emergence and expansion of a
pediment which have a concave form.
• At an advanced stage of development these pediment on both
sides of land mass join together .On this type of surface there are
isolated erosional remnants. These are the Inselbergs ,Bornhardt
and are called Monadnocks.

12. Inselberg
Bornhardt
Monadnocks

13. • He theorized that once pediment surfaces
have been formed, they persist with
little change until the next phase of
surface uplift promotes a new cycle of
river incision and escarpment retreat,
which consumes existing pediplains and
creates new ones.
• Like Davis, King envisioned impulsive
uplift and long response times of
landscape adjustment. He never
accepted the Davisian concave-convex
slope; he favored Penck’s view of
concave hill slopes and slope
replacement. On the basis of Penck's
model he conclude that the landscape
assumes the form of a series of nested,
retreated escarpments.

14. EPIGENE CYCLE OF EROSION
• The term epigene refers to the surface. Therefore the epigene
cycle of erosion is related to water and wind. In addition to
weathering, mass wasting. It doesn’t include Glacial ,marine,
volcanic and karst processes.
• King accepted the concept of stages ( i.e. at continental scale ,
there are massive erosional surfaces forming large staircase) and
rejected the concept of crustal movements for creating of slope
for cycle.
• The initiation of landscape depends upon the mode of
development of hill sides.
• There are 2 different modes of development of hill sides:-
1 .(a) Valley formation through stream incision.
(b)Formation of valley sides due to tectonic forces.
2 . Gentle lifting towards the sea. Acc. to him development of
landscape depends upon mode of stream incision.

15. Development of landscape by stream incision
• In this case valley sides are very steep because of uplift. The
longitudinal profile of the river is broken by the
development of knick points. The breaks in rivers beds form
knick points.
• The river tries to remove or erode these knick points which
recede in the upstream direction.
• River incision become important and youthful v-shaped
valleys are formed. At this stage there can 2 variations.
1) A surface can be developed into a highly dissected
plateau. For e.g. The Appalachian plateau around
Pittsburg.
2) The type of structure in a surface can provide different
types of drainage pattern.

16. Land development on tectonic forms
• His ideas on this aspect are based on his observation in coastal south Africa
particularly Drakensberg mountains. The monoclinal warping resulting in
continental scarps. These scarps are at right angle to the drainage lines.
• The drainage line are the major agent for the removal of material created
through the progress of a particular cycle. The erosional processes results in the
retreat of these continental scarp. The removal of the material results in the
parallel retreat of the scarps. Between two scarps is a cyclic landscape surface.
Different epigene cycle produce different cyclic surfaces.
• At the base of each scarp there is a knick points. The knick point and scarp
retreat at the same time. Two types of scarp can develop :-
1) Uniform wall like erosional scarp.
2) A scarp marked by dissection. The dissected part is generally located at
upper elevation.
• In such cases the land is broken into a no. of hill slope segments. This is similar
to the youthful stage after the youthful stage is over the slope experience
parallel retreat .Due to this the areas of Interfluvial divide is reduced or eroded.

17. Evaluation of King’s Concept
• Lester C King's model of landscape evolution is similar to Davis’ in
that uplift is episodic and rapid in comparison with rates of
denudation, and that the overall
morphology of a landscape at any point in time is diagnostic of its
evolutionary stages of development.
The difference: mode of slope development.
King emphasized the role of erosion alone in the formation of
pediment whereas Davis has emphasized both erosion and
deposition in the formation of pediplains.
His model is very comprehensive .
His ideas of cymatogeny is basically outside the scope of
geomorphology. It is more related to plate tectonics and geo-physics.
In most cases it has been rejected.
A fine evaluation of kings ideas is yet to be made because Acc.to
Young, the value of king’s work in providing a no. of hypothesis for
testing ,these have not yet been proved.

18. THANK YOU