4. Geomorphic processes:
All the processes including physical and
chemical changes which effect or modify the
earth’s sufficial form are called Geomorphic
processes.
5. Geomorphic Agents:
“A geomorphic agent is any medium,
which is enable of securing and
transporting earth materials”.
Thus running water including both
concentrated and unconcentrated run-off,
groundwater, glaciers, wind and movements
within bodies of standing water including
waves, currents, and tides fall in this group.
6.
Most of the geomorphic agents originate within the
earth’s atmosphere. And are also directed by the force
of gravity. Gravity is not a geomorphic agent because it
cannot secure and carry away materials. It is better
thought of as a directional force.
7. 1
2
3
• Epigene or exogenetic process
• Hypogene or endogenetic process
• Extraterrestial
8. Exogenetic processes are those processes which
originate and modify the earth’s crust from the outside
but within the atmosphere.
This process functioned by Gradation.
Gradation:
The process by which the earth's surface irregularities are
removed and a level surface is created, is known as
gradation. All gradation-processes are directed by
gravity. The processes of gradation are divisible into
two major categories Degradation and Aggradation.
9. Degradation :
is the process in which material from the high lands are
removed by the geomorphic agents as a result of which
the altitude of the highlands are reduced. Degradation
of the earth's surface is mainly carried out through :
(a) Weathering,
(b) Mass-wasting
(c) Erosion and Transportation
12.
Various Geomorphic Agents, associated Processes,
and resulting Erosional Features
1.Fluvial Process or features made by river:
Perennial streams and entrenched channels
V-shape valleys
Rapids
potholes
waterfalls
plunge pools
Alluvial terraces
meandering streams
bank erosion
Oxbow lakes
Delta etc.
14. 3.Erosional features made by Wind:
Mashroom rock
Earth piller
deflation hollows
Zeugen
Yardang
Inselberg
Desert pavement
Inkanter & driekanter
15. Aggradation:
is the process of deposition of sediments. As we
know, under favourable conditions, when the
transporting agents lose their carrying power, the
transported materials get deposited, sometimes in the
sea, sometimes on the land.
Thus the low lying tracts are gradually filled up
through deposition of sediments by running
water, ground
water, wind, glaciers, wave, currents, tides in
seas, oceans etc.
18.
These are also known as hypogene processes. These are
the processes of internal origin. In other words, a
process which originates within the earth's crust is
termed endogenetic process.
Endogenetic processes can consist of anything from
plate tectonics, earth quakes, and volcanic activities.
Endogenetic processes occurs so slowly that it is very
rare to find an unmodified landform.
20. Volcanism/ Volcanicity :
It is the phenomenon in which matter is transferred from
the earth's interior and erupted onto its surface. It is one
of the important manifestations of the dynamic nature of
the earth. The process of effusion of magmatic material
on to the surface of the earth, thus forming various
volcanic structures and flowing over the surface, is called
volcanism.
Magma beneath the crust is under very great pressure. When
folding and faulting occur, cracks or fractures which are lines
of weakness. When these lines of weakness develop
downward in the crust and reach the magma, they will release
the pressure in the magma.
This allows magma to rise up along the lines of weakness and
intrude into the crust. Some magma may even reach the earth's
surface.
21. There are two types of volcanic activities according to
their mode of occurrence.
Intrusive volcanism
Extrusive volcanism
Intrusive volcanism:
When magma solidifies below the earth’s surface it
produces igneous rock. If this rock is pushed upward
into the crust either before or after solidification, it is
called “igneous intrusion”. The intrusive process is
usually a disturbing one for Pre-existing rock.
22. The most common types of intrusive volcanoes are:
Batholith
Laccolith
Lopolith
Sill
Dike
23.
Molten magma extruded on to the surface of the
earth, where it cools and solidifies is known as “lava".
The ejection of lava into the open air is sometimes
volcanic and explosive,devasting the area for miles
around. In other cases, it is gentle and quite, affecting
the landscape more gradually.
The extrusive volcanism is primarily associated with
two major landform:
Volcanoes
Lava flows
24. There are three types of volcanoes by activity
Active or Live volcanoes
Dormant volcanoes
Extinct volcanoes
25.
An active volcano is one that has erupted in recorded
history and they’re probably going to erupt again soon.
Throughout the world there are 500 to 800 active
volcanoes, lie mostly along cirum-pacific belt or
commonly known as the “Ring of Fire.”
26. S.no
Name
Country
Year of Activity
1
Kilauea
Hawaii
1823, 1987
2
Stromboli
Italy
1768, 1952
3
Mt.St.helens
USA
1800,1887,1980
4
Volcano
Italy
1890
5
Karakatua
Sumatra,
Indonesia
1680,1969
6
Mauna Loa
Hawaii
1859, 1950
7
Mayon
philiphines
1616, 1984
8
vesuvius
Italy
1979,1906
9
Hekla
Iceland
1693, 1970
27.
28.
A dormant volcano has been quite for sometimes, but
can be erupted within recorded history, and is consider
to be potentially active.
Such dormant volcano shows evidence of recent
history.
29.
A volcano that has not been known to erupt at any
time, since its discovery is considered to be extinct.
Some old volcanoes notably California’s Mount Shasta
and Washington’s mount baker have not erupted in
recorded time and are considered extinct volcanoes.
30. Diastrophism :
“Deformation of the earth’s crust due to folding and
faulting.”
Diastrophic forces elevate or build up portion of earth’s
crust.
Diastrophic processes:
There are two types of Diastrophic processes:
Orogenic
Eperogenic
31. Orogenic Processes:
Mountain building processes that occur from
compressional forces that are generated by continued
subduction or the trapping and deformation of sediment
and crust between two colliding plates.
32. Epeirogenic Processes:
Processes that cause uplift or depression on a regional
scale and proceed without internal disruption of
original rock surfaces. It occurs in response to driving
forces.
33. Orogenic Processes
It makes Mountains
Local movement
They are small scale
They are episodic
Epeirogenic Processes
It makes plateau
Regional Movements
They are large scale
They occur at once
34. Folding:
Folding is one of the endogenetic processes. When two forces
push towards each other from opposite sides, the rock layers will
bend into folds. The process by which folds are formed are due
to compressional forces known as folding.
There are large-scale and small-scale folds. Large-scale folds are
found mainly along destructive plate boundaries.
There are three types of folds:
Monocline
Syncline
Anticline
35. Monoclines:
Are the simplest types of
folds. Monoclines occur
when horizontal strata
are bent upward so that
the two limbs of the
fold are still horizontal
In monocline Pressure
exert from one side
36. Anticlines Folds:
Anticlines are folds where the
originally horizontal strata has
been folded upward, and the
two limbs of the fold dip away
from the hinge of the fold.
Fold mountains are formed when
the crust is pushed up as
tectonic plates collide. When
formed, these mountains are
usually enormous like the
newly formed Rocky
Mountains in Western Canada
and the United States
37. Syncline:
A syncline is similar to an anticline,
in that it is formed by the
compression of a tectonic plate.
However, a syncline occurs when
the plate bends in a downward
motion.
The lowest part of the syncline is
known as the trough.
Synclines are formed when pressure
exert from both sides.
Synclines and anticlines usually
occur together such that the limb
of a syncline is also the limb of an
anticline. The lowest part of the
syncline is known as the trough.
38. Faulting:
A fault is when tension and compression associated
with plate movement is so great that blocks of rock
fracture or break apart. This process can occur very
rapidly, in the form of earthquakes. The damage
caused by this event can be very destructive and cause
severe changes to the earths surface.
39. Faults can be divided into several
different types depending on the
direction of relative displacement.
There are three types of fault which are
caused by different endogenetic
forces:
Normal fault
strike slip fault
Oblique slip fault
Faulting forms two major landforms block mountains and rift valleys.
40.
This occurs when rocks move
away from each other due to
the land moving apart.
When the rocks move apart,
the side with the less stable
tectonic plate drops below the
side with the more stable plate.
41.
Are faults where the relative
motion on the fault has taken
place along a horizontal direction.
Such faults result from shear
stresses acting in the crust. Strike
slip faults can be of two
varieties, depending on the sense
of displacement. To an observer
standing on one side of the fault
and looking across the fault, if the
block on the other side has moved
to the left, we say that the fault is
a left-lateral strike-slip fault. If
the block on the other side has
moved to the right, we say that
the fault is a right-lateral strikeslip fault.
42.
When the hanging wall
motion is neither
dominantly vertical nor
horizontal, the motion is
called oblique-slip.
Although oblique
faulting isn't unusual, it
is less common than the
normal and strike-slip
movement.
43.
The processes which are acting away from the surface of
the Earth are called Extraterrestrial processes.
Extraterrestrial processes include Meteorides.
The topographic effect of the impact of meteorites(piece of rock or
metal that has reached the earth’s surface from outer space) do not
fall within either of the above classes and are termed
extraterrestrial, which mean from beyond the limits of the earth’s
domain.
In October 2011, scientists reported that one form of extraterrestrial
material is cosmic dust which contains complex organic matter that
could be created naturally, and rapidly, by stars.
44.
A meteorite is a meteoroid (a solid piece of debris from such
sources as asteroids or comets) originating in outer space that
survives impact with the Earth's surface. A meteorite's size can
range from small to extremely large. Most meteorites derive
from small astronomical objects called meteoroids, but they
are also sometimes produced by impacts of asteroids.
When a meteoroid enters the atmosphere, frictional, pressure,
and chemical interactions with the atmospheric gasses cause
the body to heat up and emit light, thus forming a fireball, also
known as a shooting/falling star.
More generally, a meteorite on the surface of any celestial
body is a natural object that has come from elsewhere in
space. Meteorites have been found on the Moon and Mars.
45. Meteorites have traditionally been
divided into three broad categories:
stony meteorites:
are rocks, mainly composed of silicate
minerals.
Iron meteorites:
largely composed of metallic iron-nickel.
Stony-iron meteorites:
contain large amounts of both metallic and
rocky material.
Meteorites smaller than 2mm are
classified as micrometeorites.
46.
Most meteoroids disintegrate when entering Earth's
atmosphere. However, an estimated 500 meteorites ranging in
size from marbles to basketballs or larger do reach the surface
each year only 5 or 6 of these are typically recovered and
made known to scientists.
Few meteorites are large enough to create large impact
craters. Instead, they typically arrive at the surface at
their terminal velocity and create a small pit.
Even so, falling meteorites have reportedly caused damage to
property, and injuries to livestock and people.
47.
Until the 20th century, only a few hundred meteorite
finds had ever been discovered. Over 80% of these
were iron and stony-iron meteorites, which are easily
distinguished from local rocks.
To this day, few stony meteorites are reported each year
that can be considered to be "accidental" finds.
48. The meteorite fragment ALH84001 discovered in Antarctica in 1984
This small meteorite is from the
NWA 869 strewn
field, near Tindouf, Algeria..
Meteorite find
in situ
on desert
pavement, Rub'
al Khali, Saudi
Arabia.
A stony meteorite (H5) found just north
of Barstow, California, in 2006
