1. Landform:
A landform is an individual topographic feature, of whatever size; thus the
term could refer to something as minor as a cliff or a sand dune, as well as to
something as major as a peninsula or a mountain range. The plural-landforms-is
less restrictive and is generally considered synonymous with topography.
2. Topography:
The surface features of the Earth’s surface, including the relief, the terrain, the
vegetation, the soils and all the features created in the landscape by human
endeavour. It is not synonymous merely with relief.
3.Uniformitarianism:
Fundamental to understanding topographic development is familiarity with
the doctrine called uniformitarianism, which holds that ‘the present is the key to
past’. This means that the processes that formed the topography of the past are the
same ones that have shaped contemporary topography; these processes are still
functioning in the same fashion and, barring unforeseen cataclysm, will be
responsible for the topography of the future. The processes involved are not
temporary and, with only a few exception, not abrupt. They are mostly permanent
and slow acting. The development of landforms is a virtually endless event, with
2
the topography at any given time simply representing a temporary balance in a
continuum of change.
4. Geomorphic process:
Process considers the actions that have combined to produce the landform. A
variety of forces – usually geologic, hydrologic, atmospheric and biotic – are
always at work shaping the feature of the lithospheric surface, and their interaction
is critical to the formation of the feature(s).
5. Geological structure:
Structure refers to the nature, arrangement, and orientation of the materials
making up the feature being studied. Structure is essentially the geologic
underpinning of the landform. It is a dominant control factor in the evolution of
landforms. It is the overall relationship between rocks together with their large
scale arrangements and dispositions. Structure includes faults, folds, rock
massiveness, rock harness, constituent minerals, permeability or impermeability
and the like. According to W.M.Davis “Landforms are a function of structure,
process and stage”.
6. Relief:
It is the character of the land surface of the earth. It comprises a wide variety
of landforms, which can be grouped into different types of terrain. (Terrain is the
physical characteristics of the natural features of and area, i.e. its landforms,
vegetation and soils.)
7. Geomorphic stage:
a)A Davisian idea , b) The point to which a landform has evolved during a
cycle of erosion ,c) As a result of the different processes the landforms pass
through different stages – a series of orderly and sequential changes.
8. Drainage:
Drainage refers to the movement of water (from rainfall and snowmelt)
either over Earth’s surface or down into the soil and bedrock. Although moving
3
water is an outstanding force under the ‘process’ heading, the ramifications of
slope wash, stream flow, stream patterns, and other aspects of drainage are so
significant that generally the topic or drainage is considered a basic element in
landform analysis.
9. Slope:
An inclined surface, the gradient of which is determined by the amount of
the inclination from the horizontal, and the length of which is determined by the
inclined distance between its crest and its foot. A slope may be concave, straight or
convex when seen in profile.
10. Complexity:
Usually, most of the topographic details have been produced during the
current cycle of erosion, but there may exist within an area remnants of features
produced during prior cycles, and, although thee are many individual landforms
which can be said to be the product of some single geomorphic process. Horberg
(1952) classified landforms into five major categories:
1. simple
2. compound
3. monocyclic
4. multicyclic, and
5. exhumed or resurrected landscapes.
• Simple landscapes are the product of a single dominant geomorphic process,
• Compound landscapes are those in which two or more geomorphic processes
have played major roles in the development of the existing topography.
• Monocyclic landscapes have been produced during more than one cycle of
erosion. Monocyclic landscapes are less common than multicyclic and are in
general restricted to such newly created land surfaces as a recently uplifted
portion of the ocean floor, the surface of a volcanic cone, lava plain or
plateau, or areas buried beneath a cover of Pleistocene glacial deposits.
4
• Polyclimatic landscapes it has become evident in recent years that many
landscapes have evolved under more than one set of climatic conditions with
accompanying variation in the dominant geomorphic processes. Many of
these varying climatic conditions were associated with the fluctuating
climates of Pleistocene time, but are some areas certain aspects of the
topography reflect climatic conditions that existed during Tertiary times.
• Exhumed or resurrected landscapes are those which were formed during
some past period of geologic time, then buried beneath a cover 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 the Pleistocene.
11. Appreciation of world climates:
Climate 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 cove. The direct controls
are such obvious ones as the amount and kind of precipitation, its intensity, the
relation between precipitation and evaporation daily range of temperature, whether
and how frequently the temperature falls below freezing point, depth of frost
penetration, and wind velocities and directions.
12. Pleistocene climate:
There is indisputable evidence that many regions that are today arid or
semiarid had humid climates during the glacial ages. Freshwater lakes existed in
many areas which today have internal drainage. We know also that many regions
now temperate experienced during the glacial ages temperatures such as are found
now in the sub arctic portions of North America and Eurasia, where there exists
permanently frozen ground or what has come to be called permafrost conditions.
World sea levels were also affected. Withdrawal of large quantities of water from
5
the oceans to form great ice sheets produced a lowering of sea level of t least 300
feet and perhaps as much as 500 feet.
13. Internal and external Geomorphic processes:
The topography of Earth has infinite variety, apparently being much more
diverse than on any other known planet. This variety reflects the complexity of
interaction between process and structure – the multiplicity of shapes and forms
that result as the geomorphic processes exert their inexorable effects.
These processes are relatively few in number but extremely varied in nature
and operation. Basically they are either internal or external. The internal processes
operate from within Earth, energized by internal heat that generates extremely
strong forces that apparently operate outside of any surface or atmospheric
influences. These forces result in crustal movements of various kinds. In general,
they are constructive, uplifting, building forces that tend to increase the relief of
the land surface.
14. Historical extension:
Geomorphology concerns itself primarily with the origins of the present
landscape but in most landscapes there are present forms that date back to previous
geologic epochs or periods. A geomorphologist is thus forced to adopt an historical
approach if he is to – interpret properly the geomorphic history of a region.
Application of the principle of uniformitarianism makes this approach possible an
historical approaches if he is to interpret properly the geomorphic history of a
region. Application of the principle of uniformitarianism makes this approach
possible, an historical approach if he is to interpret properly the geomorphic history
of a region. Application of the principle of uniformitarianism makes this approach
possible.
15. Pursuit of Pattern:
A prime goal of any geographic study is to detect patterns in the areal
distribution of phenomena. If features have a disordered and apparently haphazard
6
distribution, it is more difficult to comprehend the processes that formed them and
the relationships that exist among them. If there is some perceptible pattern to their
distribution, it becomes simpler for us to understand both the reasons for the
distribution pattern and the interrelationships that pertain.
16. Scale:
In any systematic study of geomorphic processes, two general, topics should
be kept in mind-scale and pattern. The question of scale is fundamental in
geography. Regardless of the subject of geographic inquiry, recognizable features
and associations are likely to vary considerably depending on the scale of
observation. This simply means that the aspects of the landscape one observes in a
close up view are different from those observed from a more distant view.
At lest five orders of relief can be recognized on the surface of
lithosphere.
1.First-order relief represent the small-scale end of the spectrum, which means that
the features are the largest that can be recognized continental platform and ocean
basins. Although the shoreline at sea level appears as a conspicuous demarcation
between land and water, it is not the accepted boundary between platform and
basins, each continent has a margin that is submerged, called the continental shelf.
At its outer edge, the slope pitches more steeply and abruptly into the ocean basins.
2. Second-order relief consists of major mountain systems and other extensive
surface formation of sub continental extent(such as the Mississippi lowland or the
Amazon basin) Second- order relief features (like those of all other orders) may be
found in ocean basins as well as on continental platforms, most conspicuously in
the form of the great undersea mountain ranges usage referred to as ridges.
3. Third-order relief encompasses specific landform complexes of lesser extent and
generally of smaller size than those of the second order, with no precise separation
7
between the two. Typical third-order features include discrete mountain ranges,
groups of hills, and large river valleys.
4.Fourth-order relief comprises the sculptural details of the third-order features,
including such individual landforms as a mountain, mesa, or hill.
5.Fifth-order relief consists of small individual features that may be part of the
fourth-order relief such as sandbar, cliff, or waterfall.
A landform is an individual topographic feature, of whatever size; thus the
term could refer to something as minor as a cliff or a sand dune, as well as to
something as major as a peninsula or a mountain range. The plural-landforms-is
less restrictive and is generally considered synonymous with topography.
2. Topography:
The surface features of the Earth’s surface, including the relief, the terrain, the
vegetation, the soils and all the features created in the landscape by human
endeavour. It is not synonymous merely with relief.
3.Uniformitarianism:
Fundamental to understanding topographic development is familiarity with
the doctrine called uniformitarianism, which holds that ‘the present is the key to
past’. This means that the processes that formed the topography of the past are the
same ones that have shaped contemporary topography; these processes are still
functioning in the same fashion and, barring unforeseen cataclysm, will be
responsible for the topography of the future. The processes involved are not
temporary and, with only a few exception, not abrupt. They are mostly permanent
and slow acting. The development of landforms is a virtually endless event, with
2
the topography at any given time simply representing a temporary balance in a
continuum of change.
4. Geomorphic process:
Process considers the actions that have combined to produce the landform. A
variety of forces – usually geologic, hydrologic, atmospheric and biotic – are
always at work shaping the feature of the lithospheric surface, and their interaction
is critical to the formation of the feature(s).
5. Geological structure:
Structure refers to the nature, arrangement, and orientation of the materials
making up the feature being studied. Structure is essentially the geologic
underpinning of the landform. It is a dominant control factor in the evolution of
landforms. It is the overall relationship between rocks together with their large
scale arrangements and dispositions. Structure includes faults, folds, rock
massiveness, rock harness, constituent minerals, permeability or impermeability
and the like. According to W.M.Davis “Landforms are a function of structure,
process and stage”.
6. Relief:
It is the character of the land surface of the earth. It comprises a wide variety
of landforms, which can be grouped into different types of terrain. (Terrain is the
physical characteristics of the natural features of and area, i.e. its landforms,
vegetation and soils.)
7. Geomorphic stage:
a)A Davisian idea , b) The point to which a landform has evolved during a
cycle of erosion ,c) As a result of the different processes the landforms pass
through different stages – a series of orderly and sequential changes.
8. Drainage:
Drainage refers to the movement of water (from rainfall and snowmelt)
either over Earth’s surface or down into the soil and bedrock. Although moving
3
water is an outstanding force under the ‘process’ heading, the ramifications of
slope wash, stream flow, stream patterns, and other aspects of drainage are so
significant that generally the topic or drainage is considered a basic element in
landform analysis.
9. Slope:
An inclined surface, the gradient of which is determined by the amount of
the inclination from the horizontal, and the length of which is determined by the
inclined distance between its crest and its foot. A slope may be concave, straight or
convex when seen in profile.
10. Complexity:
Usually, most of the topographic details have been produced during the
current cycle of erosion, but there may exist within an area remnants of features
produced during prior cycles, and, although thee are many individual landforms
which can be said to be the product of some single geomorphic process. Horberg
(1952) classified landforms into five major categories:
1. simple
2. compound
3. monocyclic
4. multicyclic, and
5. exhumed or resurrected landscapes.
• Simple landscapes are the product of a single dominant geomorphic process,
• Compound landscapes are those in which two or more geomorphic processes
have played major roles in the development of the existing topography.
• Monocyclic landscapes have been produced during more than one cycle of
erosion. Monocyclic landscapes are less common than multicyclic and are in
general restricted to such newly created land surfaces as a recently uplifted
portion of the ocean floor, the surface of a volcanic cone, lava plain or
plateau, or areas buried beneath a cover of Pleistocene glacial deposits.
4
• Polyclimatic landscapes it has become evident in recent years that many
landscapes have evolved under more than one set of climatic conditions with
accompanying variation in the dominant geomorphic processes. Many of
these varying climatic conditions were associated with the fluctuating
climates of Pleistocene time, but are some areas certain aspects of the
topography reflect climatic conditions that existed during Tertiary times.
• Exhumed or resurrected landscapes are those which were formed during
some past period of geologic time, then buried beneath a cover 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 the Pleistocene.
11. Appreciation of world climates:
Climate 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 cove. The direct controls
are such obvious ones as the amount and kind of precipitation, its intensity, the
relation between precipitation and evaporation daily range of temperature, whether
and how frequently the temperature falls below freezing point, depth of frost
penetration, and wind velocities and directions.
12. Pleistocene climate:
There is indisputable evidence that many regions that are today arid or
semiarid had humid climates during the glacial ages. Freshwater lakes existed in
many areas which today have internal drainage. We know also that many regions
now temperate experienced during the glacial ages temperatures such as are found
now in the sub arctic portions of North America and Eurasia, where there exists
permanently frozen ground or what has come to be called permafrost conditions.
World sea levels were also affected. Withdrawal of large quantities of water from
5
the oceans to form great ice sheets produced a lowering of sea level of t least 300
feet and perhaps as much as 500 feet.
13. Internal and external Geomorphic processes:
The topography of Earth has infinite variety, apparently being much more
diverse than on any other known planet. This variety reflects the complexity of
interaction between process and structure – the multiplicity of shapes and forms
that result as the geomorphic processes exert their inexorable effects.
These processes are relatively few in number but extremely varied in nature
and operation. Basically they are either internal or external. The internal processes
operate from within Earth, energized by internal heat that generates extremely
strong forces that apparently operate outside of any surface or atmospheric
influences. These forces result in crustal movements of various kinds. In general,
they are constructive, uplifting, building forces that tend to increase the relief of
the land surface.
14. Historical extension:
Geomorphology concerns itself primarily with the origins of the present
landscape but in most landscapes there are present forms that date back to previous
geologic epochs or periods. A geomorphologist is thus forced to adopt an historical
approach if he is to – interpret properly the geomorphic history of a region.
Application of the principle of uniformitarianism makes this approach possible an
historical approaches if he is to interpret properly the geomorphic history of a
region. Application of the principle of uniformitarianism makes this approach
possible, an historical approach if he is to interpret properly the geomorphic history
of a region. Application of the principle of uniformitarianism makes this approach
possible.
15. Pursuit of Pattern:
A prime goal of any geographic study is to detect patterns in the areal
distribution of phenomena. If features have a disordered and apparently haphazard
6
distribution, it is more difficult to comprehend the processes that formed them and
the relationships that exist among them. If there is some perceptible pattern to their
distribution, it becomes simpler for us to understand both the reasons for the
distribution pattern and the interrelationships that pertain.
16. Scale:
In any systematic study of geomorphic processes, two general, topics should
be kept in mind-scale and pattern. The question of scale is fundamental in
geography. Regardless of the subject of geographic inquiry, recognizable features
and associations are likely to vary considerably depending on the scale of
observation. This simply means that the aspects of the landscape one observes in a
close up view are different from those observed from a more distant view.
At lest five orders of relief can be recognized on the surface of
lithosphere.
1.First-order relief represent the small-scale end of the spectrum, which means that
the features are the largest that can be recognized continental platform and ocean
basins. Although the shoreline at sea level appears as a conspicuous demarcation
between land and water, it is not the accepted boundary between platform and
basins, each continent has a margin that is submerged, called the continental shelf.
At its outer edge, the slope pitches more steeply and abruptly into the ocean basins.
2. Second-order relief consists of major mountain systems and other extensive
surface formation of sub continental extent(such as the Mississippi lowland or the
Amazon basin) Second- order relief features (like those of all other orders) may be
found in ocean basins as well as on continental platforms, most conspicuously in
the form of the great undersea mountain ranges usage referred to as ridges.
3. Third-order relief encompasses specific landform complexes of lesser extent and
generally of smaller size than those of the second order, with no precise separation
7
between the two. Typical third-order features include discrete mountain ranges,
groups of hills, and large river valleys.
4.Fourth-order relief comprises the sculptural details of the third-order features,
including such individual landforms as a mountain, mesa, or hill.
5.Fifth-order relief consists of small individual features that may be part of the
fourth-order relief such as sandbar, cliff, or waterfall.
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