Landforms Flashcards
1
Q
Endogenic Forces
A
The forces which act in the
interior of the Earth
2
Q
Exogenic Forces
A
the forces that work on the
surface of the Earth
3
Q
2 subgroups of endogenetic forces on the basis of intensity
A
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.
4
Q
Landforms created by Endogenetic forces. Explain
A
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.
5
Q
Geanticlines
A
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.
6
Q
Geosynclines
A
If warping makes a broad sedimentary area to subside down, the subsided area of the sedimentary
rocks is known as Geosync-line.
7
Q
Fold
A
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.
8
Q
Anticline
A
The up-fold part
9
Q
Syncline
A
The down fold part between 2 anticlines
10
Q
Limbs
A
Two sides of the fold
11
Q
Fold Axis
A
Passes between the limbs through the highest or lowest part
12
Q
Axis Of Anticline
A
Fold axis passing through anticline
13
Q
Axis Of Syncline
A
Fold axis passing through syncline
14
Q
Axis Plane
A
The imaginary plane which stands in the middle of the fold and passes through the fold axis
15
Q
Fault
A
If the blocks along the surface of fracture have significant movement, the feature is called Fault.
16
Q
Fault Plane
A
The surface of fracture where movement takes place
17
Q
Slickenside
A
When the Fault plane becomes smooth on account of movement of blocks
18
Q
Fault Strike
A
If the movement of blocks produces scratches on the fault plane,
the scratches are known as Fault strike.
19
Q
Fault Breccia and Gouge
A
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.
20
Q
Plain
A
Flat surface or gently rolling with elevation not more than 200m
21
Q
Plateau
A
Elevated flat or rolling land standing above from the surrounding area
22
Q
Mountain
A
Land surface with broad base and narrow summit
23
Q
Denudation
A
the process of leveling of the Earth surface by cutting form higher regions and depositing the sediments in depressions.
24
Q
Weathering
A
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.
25
Mass Wasting
Earth and rock movement due to sliding, rolling, flowing or creeping down from slopes under the influence of gravity.
26
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.
27
Deposition
the process of settling down of sediments.
28
Factors Influencing Weathering
Rock Structure,Climate,Topography and Vegetation
29
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.
30
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.
31
Chief chemical weathering processes
Hydration,hydrolysis,oxidation,carbonation and Solution
32
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.
33
Corrasion
The mechanical and vertical erosion by which the river erodes the surroundings to ease its path downhill
34
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.
35
Carrying Capacity Of A Stream
The maximum quantity or load of sediments that river can carry is called carrying capacity of a stream.
36
Three visible sections of the work of a river
(1) The Upper Mountain Course, where the main work is that of erosion.
(2) The Middle Plain Course, where the main work consists of the transportation
of the material eroded. There is also some amount of deposition.
(3) The Lower Delta Course, where deposition of the transported material is the
main work.
37
Explain upper course
The source of rivers is generally in hilly or mountainous areas. Here the volume of water is small but its
flow is very fast. The young streams, therefore, rapidly erode a channel through the rocks.
38
Gorge
If the down cutting is very rapid or if the
rock is very hard to wear out, a steep sided Gorge may be formed. A canyon is similar to a gorge but it
is much greater in size.
39
Alluvial Fan
Rivers which sweep down from steep mountain valleys on to comparatively level lands
drop their load of coarse sands and gravel as there is sudden decrease in velocity. The
load generally assumes a fan shape; hence it is called an Alluvial Fan.
40
Piedmont Alluvial Fan
The alluvial fan sometimes grows till many kilometres across and several fans together
when united they form a continuous plain known as a Piedmont Alluvial Plain.
41
Rapid,Cataracts And Waterfall
When a stream rushes over a steep slope in its bed it forms Rapid. Bigger rapids are called Cataract.
When a stream plunges down a very deep slope or over a cliff, it forms a Waterfall.
42
Explain middle area
The second stage begins when the river leaves the mountains to enter a low lying region. At this stage the volume of water has increased as the catchment area (the areas drained by a single river system) has also been increased. Some more tributaries also
join the main river. In order to cope up with the increased volume of water the river has to widen its valley. The lateral corrosion tends to replace vertical Corrasion.
The material eroded from the valley sides is then deposited on the valley floor to from a
flood plain, i.e.; that part of the river valley which is covered by water during flood.
43
Flood
Flood is temporary inundation of dry land caused due to spilling of water from river’s
bank.
44
Natural Leeves
As more and more material is deposited
on the bed of the river the normal level of
water rises and deposition occurs on the
banks which are also raised until they
form broad ridges, called natural levees,
on the both sides of the river.
45
Meanders
```
When the course of a river
lies in a flat country, it
swings from side to side in
wide loops and forms
Meanders.
```
46
Cut off or oxbow lake
An interesting type of lake known as Cut-off or Oxbow lake is formed
when a meandering river cuts across the narrow neck of land between the two
stretches, and leaves back water.
47
Braided Channel
Sometimes due to dead flatness of the surface streams, deposit their load within the
stream and Riverine Island are formed. This typical feature is called as Braided channel.
48
Explain lower course
In the lower course the main work is the deposition of material transported to form a
Delta. Before draining the water into the sea or ocean, streams deposit their load in
their path and block their mouth. When the mouth is blocked up, the level of the river
rises and the water is unable to find its way directly towards the sea. This water then
runs from the main stream and flows into several channels. Each of these channels is
called a distributary. The distributaries wander over the delta plain forming a network
of channels resembling the fingers of a hand spread out toward the sea. The whole area
gets almost triangular in shape which is made up of fine soil sediment is termed as
Delta.
49
Estuary
Gradually widening bay cutting deep inland
50
Explain types of drainage patterns
DENDRITIC - Randomly developed,treelike pattern composed of branching tributaries and a main stream
RECTANGULAR - Characterized by 90 degree changes in stream direction
TRELLIS - Forms in areas of folded rock strata
PARALLEL - Major streams trending in the same direction
51
Groundwater
Water saturated zone of rocks
52
Water Table
The upper limit of groundwater
53
Clints,Grikes And Limestone Pavement
```
In areas of limestone with steep
slope rainwater runs down the
slope in the form of rills. Due to
continuous erosion the rills get
enlarged making the surface into
a series of ridges and trenches.
The ridges are called Clints or
Lapies while the trenches are
called Grikes. The region is called
limestone pavement.
```
54
Sinkholes,swallow holes and blind valley
Stagnant water in limestone region dissolves the surface and form a funnel shaped
depression. These funnel shaped depressions are called Sinkholes.
Large sinkholes are called Swallow Holes.
When a large cavity is from under swallow holes the roof collapses and resembles a valley. Such a valley is called Blind Valley as no river flow through it.
55
Caverns
In limestone rich area groundwater dissolves weak joints. With the passage of time the
dissolving process slowly enlarges into a cavity which further converts into caverns.
56
Stalactites,Stalagmites And Cave Pillar
When limestone solvent
drips from the cave ceiling, trace amount of limestone is deposited at the point of
precipitation. The dripped solvent water still has trace amount of calcium carbonate
which it deposits just below the ceiling hanging. Ceiling hanging column is called
stalactite and column on the floor is called stalagmite. Stalactites develop ground wards
while stalagmites grow upwards. When stalactites and stalagmites meet with each
other, the resultant feature is called cave pillar.
57
Glaciers
Glaciers are slow moving river of crystalline ice masses found in high latitude and
altitude areas.
58
Firns or naves
In cold regions snowfall ice gets accumulated and compacted due to weight of layers of
snow. The snow at the bottom get compressed and crystallized into dense ice called as
Firn or Nave.
59
Types Of Glaciers
Continental Glaciers and Mountain Glaciers
60
Continental Glaciers
very vast expansion of thick layer of ice on a flat surface are called Continental Glacier. Greenland and Antarctica have continental type of glaciers.
61
Nunatkas
When small peaks peep out of the continental glaciers surface they are called as
Nunatkas.
62
Ice Bergs and Ice Shelves
While reaching at the shore big pieces of snow block get detached with the glacier and float in sea or ocean. The floating ice blocks are called ice bergs.
A very massive size of floating ice bergs are called as ice shelves.
63
Mountain Glaciers
Mountain glaciers are tongue shaped. When these glaciers descend on the mountain
slope and reach below the snow line they start melting.
64
Piedmont Glaciers
When several glaciers meet together at the foothills they are termed as Piedmont glacier.
65
Cirque
Bowl shaped depression with steep wall on three sides and down valley side opening
feature is called Cirque.
66
Bergschrund
Advancing glacier on the vertical
| wall develops deep crevasse (crack) these are termed as Bergschrund.
67
Tarn
During summer
snow melts and leaves behind a small lake at the bottom of cirque. These lakes are
called Tarn.
68
Col
When two cirques are formed back to back (common head wall) the feature made
is termed as a col.
69
Aretes and Matter Horns
Sharp edged ridges are called arêtes. They resemble a knife.
The summits are free from ice as they are very narrow and due to frost action ice rolls down immediately. A pyramid shaped arêtes edged peak and cirques surrounding it from all directions is called Horn or Matter Horn.
70
Hanging Valleys
Hanging valleys are formed at the confluence points of the main
glacier and its tributary glacier. As the base level of main glacier and tributaries glaciers
are different, so the tributary glacier valley seems to be hanging above the main valley.
71
Roche Mountanee
These are small streamlined hills on the rocky surface.
72
Tills
Rock debris fallen into glaciers
73
Lateral,Medial,Terminal and Ground Morraine
The rock debris that falls into the glacier along the margin forms a lateral pattern of
unsorted rock debris. This lateral pattern is called Lateral Moraine. When two glaciers
coalesce to form a single glacier, the till that was carried along the edges of each glacier
joins to form a single dark strip of debris within the newly enlarged glacier, the joint till
strip is called as Medial Moraine. At the snowline the glaciers melts and deposit tills in
convex arc form. This convex shaped till deposit is termed as Terminal Moraine.
Sometimes when glacier ablation exceeds the nourishment, they recede. The receding
enables the glacier to make a new terminal moraine. When this process continues for
several times then a rolling layer of till is laid down, this is termed as Ground Moraine.
74
Fluvio-Glacial Deposits
Fine clay formed by rolling tills in glaciers is called Boulder clay. When boulder clay
get deposited on whale back shaped elongated hills of low height they are called Drumlins. Drumlins have steep slope facing the snow while elongated tail is in the direction of advancement of glacier.
When boulder clay gets deposited in a vast area they form Outwash Plain. Sometimes
boulder clay is deposited in the form of small mound known as kame. Small
depressions in outwash plains are called Kettles. Eskers are another interesting feature
made by melted glacier water. They are long, narrow and sinuous ridge composed of
gravels and sand.
75
Capes and Bays
When alternate hard and soft rocks are found near coast, the soft rock
is worn away by waves while the hard rock remains resistant of erosion. Due to
wearing away of soft rocks sea inlets are formed. These sea inlets are called bays while
the protruding hard resistant rocks are called capes.
76
Sea Cliff and Wave cut platforms
Sea cliffs are bench like features with almost vertical wall and wide flat
platform in front. In areas of high land, sea waves erode the coastal rock between the
region of high tide and low tide. As the cliff recedes a flat platform is made in front of
cliff known as Wave Cut Platform.
77
Sea Caves, sea arches, sea stacks and stumps and blowholes
When waves wear away the softer and highly fractured rocks located at the shore it
forms sea cave. When two sea caves on opposite sides of a common shore-land rock
gets united they form Sea Arch. Sometimes the roof of arch collapses and an isolated
remnant pillar like structure is left behind. This rock pillar is called as Sea Stack. The
worn down sea stack which is visible during low tides only are called stumps.
Blow holes: When water splashes against sea cave, they trap the air inside the cave by
blocking the mouth. The compressed air exerts pressure on the rock and weakens the
roof of the cave. Continuous action leads to formation of hole in the roof of the cave.
The formed feature is called Blow Hole which whistles at the time of splashing water at
the cave mouth.
78
Beaches
They are formed by deposition of sand, gravels, pebbles and marine organism shells
laid down along the coast. Beaches made up of gravels and pebbles are called Shingle
Beaches while beaches made up of sand are called Sandy Beaches.
79
Spits,hooked spit and tombolo
Spits are long slender sandbars deposited by sea waves. They are connected with
the mainland from one side while another side ends into open water of sea. When
another spit develops from the main one towards the mainland, they are called Hook or
Hooked Spit.
Tombolo: Tombolo is sandbar connecting an island with the main land.
80
Lagoon
Lagoon is an enclosed water body. When sandbar develops along the coast and
encloses the sea water leaving a small inlet through which water can move in or out is
called lagoon.
81
Ventrifacts,Dreikanter
Ventrifacts: Multifaceted, sharp edged pebbles are called Ventrifacts. These are made
by mechanical weathering by wind. Stone with three facets is called Dreikanter.
82
Mushroom Rock
In arid regions strong winds carry heavy load near surface called as
Bed Load. These bed loads moves by skipping or bouncing on the surface –termed as
Saltation. Light weight particles remains in suspension in air and they are called
Suspended Load. As the bed loads are bigger in size they abrade and scoop out rocks
more near the surface. The suspended load which are lighter they do not scoop that
much. Result of two, rocks in arid area get shaped as mushroom and termed as
Mushroom Rock or Rock Pedestals or Gour.
83
Yardangs and Inselbergs
These are found in areas where hard and soft rocks are found in alternative
vertical bands parallel to the direction of wind. Strong winds wear away soft rocks
leaving behind hard rocks. It results into formation of ridged landscape or furrow called
as yardangs.
Inselberg: Inselberg is controversial
landform of arid region as few such similar
structures are seen in glacial areas.
These are conical or dome shaped isolated
rocky hills. They are mostly made up of
hard rocks like granite and gneiss etc.
84
Sand Dunes
Sand dune is a heap of sand made by wind. These can be formed into many shapes. Sometimes wind elongates the margins of sand dunes in the direction of wind which gives it a crescent shape. These crescent shaped dunes are called Barchans.
Due to continuous blowing of wind in one direction for long period of time either of the horn gets extended.
The elongated dunes are called Longitudinal Dunes or Seif Dunes.
85
Loess
Loess are made by deposition of very fine sand and dust particles blown from
one place and settled at distant place.
86
Soil
The brown loose grainy particle that covers most of the Earth’s land surface is called Soil.
