DEFINITION AND PRINCIPLES OF GEOMORPHOLOGY PRESENTATION.pptx

DEFINITION AND PRINCIPLES
OF GEOMORPHOLOGY
GROUP MEMBERS:
 Aashi Rastogi (2023/26)
 Aditi (2023/1655)
 Aditi Tripathy (2023/51)
 Amisha Kumari (2023/79)
 Ankita Garg (2023/141)

DEFINITION OF GEOMORPHOLOGY
Geomorphology is a significant branch of Physical Geography. It is derived from the
Greek words i.e., ‘geo’ meaning Earth, ‘morphe’ meaning form and ‘logos’ meaning study.
Geomorphology is thus defined as the science of description of various landforms
present on the surface of the Earth.
A.L. Bloom defined Geomorphology as the systematic description and analysis of
landscapes and the processes that change them.
The subject matter of geomorphology can be organised on the basis of 1)dimension and
scale of relief features 2)processes that shape the landforms and 3)approaches to the
geomorphic studies.

PRINCIPLES OF GEOMORPHOLOGY
CONCEPT 1
‘The same physical processes and laws that operate today, operated throughout the
geologic time, although not necessarily with the same intensity as now.’
This is the underlying principle of modern geology and is known as the principle
of uniformitarianism.
It was first enunciated by Hutton in 1785, beautifully reinstated by Playfair in1802
and popularised by Lyell in his numerous editions of ‘Principles of Geology’.
Hutton taught that ‘the present is the key to the past’ but applied this principle too
rigidly and argued that geologic processes operated at the same intensity
throughout the geologic time.

CONCEPT 2
Concept 2 says -"Geologic structure is a dominant control factor in the
evolution of landforms and is reflected among them."- Structure here
includes the phenomena related to rock like rock passiveness, permeability
of rocks etc.
Examples-1. The increasing application
of geomorphic interpretation of aerial
photographs are done by the help of
this concept .

CONCEPT 3
It says-"Geomorphic processes leave their distinctive imprint upon
landforms and each geomorphic process develops it's own
characteristic assemblage of landforms."- It applies to both endogenic
as well as exogenic processes.
Endogenic includes volcanism and earthquake . Exogenic ones
include weathering , mass wasting and erosion.
Example-Landforms are classified on the genetic classification.
It also emphasis the genetic relationships of landform assemblages.

As the different erosional agents act upon the earth's surface there is produced an
orderly sequence of land forms. The land forms possess distinctive characteristics
depending upon the stage of their development. This idea was most stressed by W.
M. Davis and out of this idea grew his concept of geomorphic cycle and its
concomitant stages of youth, maturity, and old age culminating in a topographic
surface of low relief called peneplain. Use of the term geomorphic cycle will carry
with it implication of orderly and sequential development but there will be no
implication that designation of the topography to a certain area as youthful, mature
or old means that the topography of another region in the same stage of
development has fully comparable characteristics. .
As the different erosional agencies act upon the earth's sur-
face there is produced a sequence of land forms having distinctive characteristics
at the successive stages of their development.
Concept 4

Under varying conditions of geology, structure, and climate land form characteristics may
vary greatly even though the geomorphic processes may have been acting for comparable
periods of time. Partial cycles are more likely to occur than completed ones, for much of
the earth's crust is restive and subject to intermittent and differential uplifts.

CONCEPT 5
Complexity of geomorphic evolution is more common than
simplicity.
COMPLEXITY OF GEOMORPHIC EVOLUTION IS MORE COMMON THAN SIMPLICITY.
USUALLY MOST OF THE TOPOGRAPHIC DETAILS HAVE BEEN PRODUCED DURING
THE CURRENT CYCLE OF EROSION, BUT THERE MAY EXIST WITHIN AS AREA
REMNANTS OF FEATURES PRODUCED DURING PRIOR CYCLES. COMMONLY WE
ARE ABLE TO RECOGNISE THE DOMINANCE OF ONE CYCLE. HORBERG (1952)
DIVIDED THE LANDSCAPES INTO FIVE MAJOR CATEGORIES:
(1) simple, (2) compound, (3) monocyclic, (4) multicyclic and (5) exhumed.

Simple landscapes are those which are the product of a
single dominant geomorphic process, compound
landscapes are those in which more than one
geomorphic processes have played major role in the
development of existing topography. Monocyclic
landscapes are those that bear the imprint of only one
cycle of erosion; multicyclic landscapes have been
produced during more than one cycle of erosion. Much of
the earth's topography bears the imprints of more than
one period of erosion. Exhumed or resurrected
landscapes are those which were formed during some
past period of geological time, then buried beneath a
cover mass of igneous or sedimentary origin, then still
later exposed through removal of the cover. Topographic
features now being exhumed may date back as far as the
Precambrian or they may be as recent as Pleistocene.

Little of the earth's topography is older than tertiary and most of
it no older than Pleistocene".
Concept 6
The geologic structures are in general much older than topographic features
developed upon them except in area of late Pleistocene and recent diastrophism.
Most of the details of our present topography probably do not date back of the
Pleistocene, and certainly little of it existed as surface topography back of the
tertiary.

CONCEPT 7
Pleistocene have had far-reaching effects upon present-day
topography. Glaciation directly affected many million square
miles, perhaps as much as 10,000,000 square miles, but its effects
extended far beyond the areas actually glaciated.
Glacial outwash and windblown materials of glacial origin
extended into areas not glaciated, and climatic effects were
probably worldwide in extent.
Proper interpretation of present-day landscape is impossible without
a full appreciation of the manifold influences of the geologic and
climatic changes during the Pleistocene".

CONCEPT8
An appreciation of world climate is necessary to a proper
understanding of the varying importance of the different
geomorphic processes".
Climatic variations may affect the operation of geomorphic processes either
indirectly or directly.The indirect influences are largely related to how climate
affects the amount, kind, and distribution of the vegetal cover.The direct
controls are such as the amount and kind of precipitation, its intensity, the
relation between precipitation and evaporation and daily range of
temperature, whether and how frequently the temperature falls below.
3

The climatic factors especially precipitation and temperatures influence the
operation of the geomorphic processes

CONCEPT 9:
The concept stresses on the need to extend the geomorphologic studies of
landforms back in geological time to delineate geomorphic evolution.
Geomorphology concerns itself primarily with the origins of the present
landscape but in most landscapes there are present forms that date back to
previous geological epochs or periods. Geomorphic studies should not be
limited or confined to identification and documentation of landforms. The
full significance of geomorphic studies is realised only by interpreting the
past geologic history of the landforms and landscapes.
“Geomorphology, although concerned primarily with
present-day landscapes, attains its maximum usefulness
by historical extension”.

The full significance of geomorphic studies is realised only by
interpreting the past geologic history of the landforms and landscapes. A
geomorphologist is thus forced to adopt an historical approach if he is to
interpret properly the geomorphic history of a region. The paleo-
geomorphology covers the identification of ancient erosion surfaces and
study of ancient topographies.
This is an important aspect of geomorphology as the landscapes
continue to be modified and evolved over a period of time. By doing so, a
full history of the development of landscapes can be delineated and
understood.

The concept attributes to large variations of relief of the Earth’s
surface to different rates at which the geomorphic processes
operate. As a result, the area where rate is erosion is faster
, will
attain lower elevation in comparatively shorter period of time
while area with slower erosion will attain the same relief over a
longer period of time. Consequently, at a given point of time, both
areas will be at different elevations.

CONCEPT 10: “To a large degree the Earth's surface possesses relief
because the geomorphic processes operate at differential
rates”.
The earth’s surface is not even. The rocks of the earth's crust vary in their
lithology and structure and hence offer varying degrees of resistance to the
gradational processes. Differences in rock composition and structures are
reflected not only in regional geomorphic variability but in the local
topography as well. The extent of Earth’s relief variations is reflected by high
peaks of mountain ranges and depths of oceans.The local intensity of
particular processes may change notably in response to differences in such
factors as temperature, moisture, altitude, exposure, topographic
configuration, and the amount and type of vegetal cover.

Conclusion
8
Thornbury's "Concepts of Geomorphology"
serves as a foundational text in the field,
providing a framework for understanding the
complexities of landscape evolution. His
insights into dynamic equilibrium,
evolutionary perspectives, spatial and
temporal scales, interdisciplinary approaches,
and human impacts continue to shape
geomorphological research and guide efforts
to address pressing environmental challenges.

DEFINITION AND PRINCIPLES OF GEOMORPHOLOGY PRESENTATION.pptx

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