Landforms Flashcards
Endogenic Forces
The forces which act in the
interior of the Earth
Exogenic Forces
the forces that work on the
surface of the Earth
2 subgroups of endogenetic forces on the basis of intensity
a) Sudden Endogenetic forces – The main forces in this sub-group are volcanic eruption or Earthquake. Landscape undergoes disintegration suddenly. For example, production of deep fissures in plain areas, the sudden changes in the routes of river, the formation of small hills, etc; are some of the effects of these forces.
b) Diastrophic forces – These forces act very slowly. Their effect becomes discernable after thousands of years. For example, the coast of the Baltic Sea rises
by 1.3 metres in a century.
Landforms created by Endogenetic forces. Explain
a) Crustal bending – Diastrophic forces raise an area at a place. Broad domes are created in this process. The
process of dome-formation is known as warping.
When the endogenetic forces, instead of raising the area force it down, the rocks become concave and a broad basin is formed.
Geanticlines
These basins are thus formed by a process which
is opposite to dome formation. These basins are filled in by sediment. If contraction
process takes place over a broad area, sedimentary rocks hundreds of meters deep are
warped up. The sedimentary area thus warped up is known as Geanticlines.
Geosynclines
If warping makes a broad sedimentary area to subside down, the subsided area of the sedimentary
rocks is known as Geosync-line.
Fold
Fold – When compression takes place on the crust due to endogenetic forces, a part of
the crust is raised up in the form of folds. The area is contracted in this process. Due to
the forces acting upon it, the crust takes a wave like form.
Anticline
The up-fold part
Syncline
The down fold part between 2 anticlines
Limbs
Two sides of the fold
Fold Axis
Passes between the limbs through the highest or lowest part
Axis Of Anticline
Fold axis passing through anticline
Axis Of Syncline
Fold axis passing through syncline
Axis Plane
The imaginary plane which stands in the middle of the fold and passes through the fold axis
Fault
If the blocks along the surface of fracture have significant movement, the feature is called Fault.
Fault Plane
The surface of fracture where movement takes place
Slickenside
When the Fault plane becomes smooth on account of movement of blocks
Fault Strike
If the movement of blocks produces scratches on the fault plane,
the scratches are known as Fault strike.
Fault Breccia and Gouge
Rock waste is produced by the movement of blocks. If the rock waste has rough fragments, it is known as Fault Breccia but if it has fine particles it is
called Gouge.
Plain
Flat surface or gently rolling with elevation not more than 200m
Plateau
Elevated flat or rolling land standing above from the surrounding area
Mountain
Land surface with broad base and narrow summit
Denudation
the process of leveling of the Earth surface by cutting form higher regions and depositing the sediments in depressions.
Weathering
the process of decomposing and disintegrating of Earth surface (rocks) due to exposure at or near the Earth surface. It changes hard rock into fine fragments
and soft residual masses.
Mass Wasting
Earth and rock movement due to sliding, rolling, flowing or creeping down from slopes under the influence of gravity.
Erosion
the wearing away of the top layer of the Earth’s surface by different agents of denudation e.g.; running water, blowing wind, moving glacier; etc.
Deposition
the process of settling down of sediments.
Factors Influencing Weathering
Rock Structure,Climate,Topography and Vegetation
Types Of Weathering. Define also
Weathering process can be divided into two large groups as Physical Weathering or
Mechanical weathering and Chemical weathering.
Physical weathering is the process of disintegration of rocks into fine particles from
massive rock by the exertion of stresses sufficient to fracture the rock, but do not change
its chemical composition.
Chemical weathering is the decomposition of soil and rock (change in composition) by
chemical processes.
Explain types of physical weathering.
Granular disintegration – It is process in which rocks are disintegrated into small particles due to alternate expansion and contraction during day and night.
Exfoliation: In this process rocks get disintegrated in the form of layer from top
to bottom.
Block disintegration: When rocks are disintegrated in the form of blocks, it is called as block disintegration.
Shattering: it is a type of disintegration in which rocks are broken into small pieces with angle and sharp corners edges.
Organic: plants and trees sometimes put pressure on the surface of the rock and
that break it into small pieces.
Chief chemical weathering processes
Hydration,hydrolysis,oxidation,carbonation and Solution
Three Main activities involved in landform creation. Explain
There are mainly three activities involved in Landform creation namely
Erosion, Transportation and Deposition.
Erosion by a stream is the progressive removal of mineral material from the sides
and floor of the river channel.
Transportation consists of movement of the eroded particles by dragging along
the bed by suspension in the water.
Deposition is accumulation of transported particles on the floor of stagnant
water body into which the rivers drain their water.
Corrasion
The mechanical and vertical erosion by which the river erodes the surroundings to ease its path downhill
How do streams carry their loads?
Streams carry its loads in three principle form i.e.;
Dissolved matter is transported invisibly in the form of chemical ions.
Suspended load are those particles that remain hanging and flow in turbulent eddies in the stream.
Bed load are those heavy particles that settle down on the river bed and they roll or slide on the river bed.