NCERT Physical

The origin and evolution of the earth

1. Nebular Hypothesis (Nebular Hypothesis, Laplace) - Planets were formed out of a cloud of materialassociated with a youthful sun,binary theory

2. Chamberlain and Moulton - cigar shaped extension of material, wandering star, material revolved aroundthe sun, condensed gradually, binary theory

3. Schmidt in Russia and Carl Weizascar in Germany - sun surrounded by solar nebula, Helium & hydrogen&  dust, friction and collision disk-shaped cloud, planet process of accretion

4. Big Bang Theory (Expanding universe) tiny ball - small volume, infinite temperature and infinite density.Big Bang tiny ball explode, expansion, 13.7 billion years ago, In first three minutes first atom began to formAfter 300,000 years temperature dropped to 4,500 K, gave rise to atomic matter, The universe became

transparent

5. Basis of development of galaxies - Uneven distribution of matter and energy, Density differences riseto differences in gravitational forces, matter get drawn together, diameter 80,000-150,000 light years

6. The Star Formation - Accumulation of hydrogen gas in cloud nebula, localised clumps of gases, gave riseto denser gaseous body star (5-6 B years ago)

7. The planet Formation core to the gas cloud and a huge rotating disc of gas, dust develop around core gas cloud starts getting condensed, matter around the core develops into small rounded object, By process

of cohesion planetesimals are formed (large no of smaller bodies) planetesimals accrete forming planet

8. OUR SOLAR SYSTEM 5-5.6 B years ago, planet 4.6 B years ago, 8 planets mercury, venus, earth and mars are inner planet, Terrestrial, made up of rock, high densities,  Rest four outer, Jovian or Gas Giant planet, larger, thick atmosphere of helium and hydrogen, Belt of asteroids between inner and outer

 9. The difference between terrestrial and Jovian 

Inner planet too warm for gases to condense into solid particles (Jovian were distant)The solar wind blew of most of the gas&dust in inner planet (not intense for outer)Lower gravity could not hold gases

10. Formation of moon 

Old theory: Depression in pacific ocean Present theory : Outcome of giant impact,(the big splat) body  one to three times of mars collided into theearth (4.4 B years ago)

11. EVOLUTION OF THE EARTH :Earth in volatile state during primordial stage Due to gradual increase in density the temperature inside has increased as a result material getting

separated depending on their densities. Process of differentiation earth forming material separated into different layers. cooled further and solidified and condensed into a smaller size.

12. Evolution of Atmosphere and HydrosphereOrigin of Life -  Chemical reaction, complex organic

molecules, assembling, assemblage able to duplicate converting inanimate matter into living substance.(3,800 million years ago evolution started.)

First stage Loss of primordial atmosphere. (hydrogen and helium, stripped off by the solar winds)In the second stage the hot interior of the earth contributed to the evolution of the atmosphere. [Cooling of

the earth, gases and water vapour were released from the interior solid earth (degassing)] In the third stage the composition of the atmosphere was modified by the living world through the process

of photosynthesis Early atmosphere largely contained water vapour, nitrogen, carbon dioxide, methane, ammonia and very

little of free oxygen.  Continuous volcanic eruptions contributed water vapour and gases Water vapour condensed - Carbon dioxide dissolved in rain water (Temp decrease), Further rainfall further

cooling, oceans (Oceans are 4B years old)3,800 million years ago, life began to evolve, 2,500-3,000 million years ago photo synthesis evolved, Oceans contribution to oxygen through photosynthesis, Saturated by oxygen (2000 years ago), Oxygen

flooded atmosphere

13. Geological time scale :  Eons, Era, Period, Epoch (Current Eon Phanerozoic)Modern man - Cainozoic, Quaternary, Holocene  (Homo sapiens quaternary)Tertiary - Early human ancestor (Pliocene epoch), HimalayasCretaceous - Meteor, Extinction of Dinosaurs (Mesozoic)Carboniferous - Vertebrate, Coal (Paleozoic) [Not Indian coal]First life on land - Silurian (Paleozoic Era)Anthropocene (Unofficial human beings dominated)Hadean - Ocean Pre Cambrian - Aravalis 

Devonian - Age of fishes

INTERIOR OF THE EARTH

1. Direct Observation - Mining (S Africa 3-4 km), Deep Ocean Drilling Project & Integrated Deep OceanDrilling Project (Kola mine Arctic Ocean Russia 12 km), Volcanic erruption

2. Indirect Observation - meteors (meteorite)- made up of same matter than of earth, gravitationalanamolies, magnetic field, and seismic activity

3. (g) is not the same at different latitudes on the surface - It is greater near the poles and less at theequator (uneven distribution of mass of material within the earth influences this value) [Difference known asgravity anomaly]

4. Earthquake Rocks along a fault tend to move in opposite directions, overlaying rock strata press them, friction

locks them together, When movement overcome friction earthquakes occuresPoint where the energy is released - focus (Hypocentre)point on the surface nearest to the focus is epicentre (first one to experience the waves). All natural earthquakes take place in the lithosphere. (200 km)

5. Earthquake Waves Shadow Zone - P-waves between 105° and 145° from epicentre, S-waves

beyond 105°, 40% of earth surface s waves, S>P (Divide circle in half) Body waves are generated due to the release of energy at the focus and move in all directions

travelling through the body of the earth Body wave + surface rock = surface wave (move along surface, last recorded on seismograph,

most destructive)P - waves - Body, Faster, travel through all medium, vibrate parallel to direction of wave

(Longituidinal), creates density difference and stretching and squeezing of the material. (Like soundwaves)

S - waves - body, time lag, travel only through solid, perpendicular motion(Transverse) , createstroughs and crests, shear stress

Rayleigh waves - surface, travel near the surface of solids, both longitudinal and transverse Love waves/Q waves - surface waves, transverse waves, ground shake side waves with no

vertical motion

6. Types of Earthquakes - tectonic sliding rock along fault, volcanic earthquake, collapse earthquakes(mining roof collapse causing minor tremor), explosion earthquakes (explosion of chemical and nuclearbomb), reservoir induced earthquakes (dams)

7. Richter scale- magnitude (0-10) [devastating effect 5+, 8+ are quite rare; they occur once in 1-2 yearswhereas those of ‘tiny’ types occur almost every minute.]

8. Mercalli scale - intensity (1-12) 9. Effects of earthquakes - (i) Ground Shaking (ii) Differential ground settlement (iii) Land and mud slides

(iv) Soil liquefaction (v) Ground lurching (vi) Avalanches (vii) Ground displacement (viii) Floods from damand levee failures (ix) Fires (x) Structural collapse (xi) Falling object (xii) Tsunami (If epicentre belowocean, caused by tremors not by earthquake)

10. STRUCTURE OF THE EARTHThe Crust - Brittle, oceanic crust thinner(SIMA, but denser 3, to 5km, basalt), continental

thicker(SIAL, less denser 2.7, 30km to 70km in Himalayas)The Mantle - extend from Moho’s discontinuity to 2,900 km, Upper portion asthenosphere (upto

400 km, magma source(3.4 density)), lower mantle solidLithosphere - The crust and the uppermost solid part of the mantle(10-200 km)The Core - Start from Gutenberg discontinuity, Outer liquid (reason of change in magnetism, til

5100 Km), inner solid (till 6378 Km), mantle core boundary density 5 g extend to 13 gm in core, Nife

layer

11. Volcanoes -1. Contains lava flows, pyroclastic debris, volcanic bombs, ash, dust, gases such as nitrogencompounds, sulphur compounds and minor amounts of chlorine, hydrogen and argon.

Shield Volcanoes - largest of all the volcanoes, Hawaai, basalt (fluid hence spread), becomeexplosive if somehow water gets into the vent else low explosive, The upcoming lava moves in theform of a fountain and throws out the cone at the top of the vent and develops into cinder cone. egHawai island, Reunion island

Composite Volcanoes - Cooler & viscous lava than basalt, explosive eruptions, lava, largequantities of pyroclastic material and ashes, Accumulation near vent, lava act as cement,formation of layer hence composite mountain eg Mount kilimanjaro

Caldera - Most explosive that when they erupt they tend to collapse on themselves rather thanbuilding tall structure, Collapsed depression caldera, explosiveness indicates magma chamber ishuge and in close vicinity eg lake Fujiyama

Flood Basalt Provinces - Highly fluid lava, Series of flow can attain thickness about 50 km,Deccan lava plateau (Earlier was much larger)

Mid-Ocean Ridge Volcanoes - oceanic area, more than 70,000 km longAsh & Cinder cone - Do not have lava, smaller height, broken rock &ashesParasite mountain - Mount Shasta

12. Volcanic Landforms - Igneous rocks are classified as volcanic rocks (cooling at the surface) and plutonic rocks

(cooling in the crust).Intrusive Forms - lava cools within crustBatholiths - Large body, cool deeper, in the form of large dome, granitic, cooled portion of magma

chamber, appear only after denudation Lacoliths - Large dome shaped connected by pipe like conduit, resemble to composite volcanic

dome, Karnataka plateau is spotted with domal hills of granite rocks ( batholiths as well) Lapolith - Weak plane lava move horizontal, concave to the sky body

Phacolith - Base of synclines or at the top of anticline, Lens shaped, wavy materials have adefinite conduit

Sills/ Sheet - Horizontal bodies, thinner are sheet Dykes - lava through cracks, fissure developed, solidify near perpendicular to ground, e western

Maharashtra area (feeders for the eruptions that led to the development of the Deccan traps.)

DISTRIBUTION OF OCEANS AND CONTINENTS

1. Abraham Ortelius - First to propose idea Europe and Africa joined together2. Antonio Pellegrini - Drew map of three continent together 3. Continental Drift Theory (Alfred Wegener, 1912)

Pangaea & Panthalassa -> 200 Millions years ago Pangaea broke into Laurasia and Gondwanaland andTethys sea -> Current scene Force for Drifting in CDT - pole fleeing force, tidal force, totally inadequate ( bulge at equator rotation ofthe earth) Evidences

Jig saw fit - Bullard in 1964, Tried 1000 fathom line instead shorelineRocks of Same Age Across the Oceans - marine deposits along the coastline of South America and

Africa are of the Jurassic age suggests the ocean did not exist prior, Brazil and west Africa rock Tillite - sedimentary rock formed out of deposits of glaciers, Gondawana system of

sediments sediments from India have six( Africa, Falkland Island, Madagascar, Antarctica andAustralia) counter part in different landmasses of southern hemisphere, Evidences of palaeoclimate

Placer Deposits - gold bearing veins Brazil plateau & gold deposits of the Ghana Coast (absenceof source rock in region)

Distribution of Fossils - Lemurs occur in India, Madagascar and Africa (Lemuria), Mesosaurus( shallow brackish water) the Southern Cape province of South Africa and Iraver formations of Brazil.

4. Convectional Current Theory(Arthur Holmes, 1930) - convection currents in mantle, radio reactivematerial, temperature difference, Mid oceanic ridges, trenches, oceanic crust is younger, equidistant midoceanic ridges

5. Ocean Floor Configuration - continental margins (continental shelf, continental slope, continental rise anddeep-oceanic trenches), deep-sea basin/Abyssal Plains(Sediments deposit) and mid-ocean ridges (longestmountain-chain on surface of earth, crest is the zone of intense volcanic activity)

6. Distribution of Earthquakes and Volcanoes -

7. CONCEPT OF SEA FLOOR SPREADING (Harry Hess,1961) -

Evidences - midoceanic ridges, volcanic eruptions are common, Equidistant rock similar

( formation, chemical compositions and magnetic properties), Nearer rock younger and normalpolarity, oceanic crust is nowhere more than 200 million years old (Continental 3200), sediments unexpectedly thin, deep trenches have deep-seated earthquake mid oceanic ridge, quake foci shallowdepths.

Theory - constant eruptions at the crest of oceanic ridges cause the rupture of the oceanic crust,Push to oceanic crust, Ocean floor spread (does not cause shrinking of other), Sinks down at oceanictrenches: consumption of the oceanic crust

8. PLATE TECTONICS (McKenzie, Parker, Morgan, 197 independently)

Tectonic Plate - Lithospheric plate, massive, irregular, slab of solid rock, Oceanic (if large part ocean) +Continental, move horizontally over the asthenosphere as rigid units, thickness 5-100km ocean & 200continental

Theory -

Seven major plates - Young Fold Mountain ridges, trenches, and/or faults surround these major plates

I Antarctica and the surrounding oceanic plate

II North American (with western Atlantic floor separated from the South American plate along the Caribbeanislands) plate

III South American (with western Atlantic floor separated from the North American plate along theCaribbean islands) plate

IV Pacific plate

V India-Australia-New Zealand plate

VI Africa with the eastern Atlantic floor plate

VII Eurasia and the adjacent oceanic plate

Some important minor plates -

(i) Cocos plate : Between Central America and Pacific plate

(ii) Nazca plate : Between South America and Pacific plate

(iii) Arabian plate : Mostly the Saudi Arabian landmass

(iv) Philippine plate : Between the Asiatic and Pacific plate

(v) Caroline plate : Between the Philippine and Indian plate (North of New Guinea)

(vi) Fuji plate : North-east of Australia (vii) Juan de Fuca plate (between Pacific and North American plates)

Indian subcontinent (mostly Peninsular India) is traced with the help of the rocks analysed from the Nagpurarea.

Types of boundaries -

Divergent Boundaries - spreading sites, Mid-Atlantic Ridge At this, the American Plate(s) is/are separatedfrom the Eurasian and African Plates.

Convergent Boundaries - subduction zone shrinking occurs, Ocean continent, Ocean Ocean, ContinentContinent

Transform Boundaries - Crust not produced not destroyed, horizontally side pass, transform faultperpendicular to mid oceanic ridges, differential movement of a portion of the plate away from the axis ofthe earth, rotation of the earth has its effect on the separated blocks of the plate portions.

Rates of Plate Movement - strips of normal and reverse magnetic field that parallel the mid-oceanic ridgeshelped, Arctic Ridge slowest, East Pacific Rise near Easter Island, in the South Pacific fastest

Force for the Plate Movement - Heat within the earth comes from two main sources: radioactive decayand residual heat, conventional current

MOVEMENT OF THE INDIAN PLATE -

In the east, Rakinyoma Mountains of Myanmar towards the island arc along the Java Trench

Eastern margin - spreading site, east of Australia as oceanic ridge in SW Pacific

Western margin follows Kirthar Mountain of Pakistan

Makrana coast and joins the spreading site from the Red Sea rift southeastward along the ChagosArchipelago.

India and the Antarctic plate boundary is marked by oceanic ridge ( W-E direction), south of New Zealand

Tethys Sea separated India from the Asian continent till about 225 million years ago.

India collided with Asia about 40-50 million years ago (Himalaya)

Deccan Traps. 60 million years (Reunion)

Height of the Himalayas is rising even to this date.

MINERALS AND ROCKS

1. oxygen (46.6), silicon, aluminium, iron, calcium, sodium, potassium and magnesium (98%) 2. Minerals - natural, organic&inorganic, orderly atomic structure, definite chemical composition and physical

properties (Single element minerals sulphur, copper, silver, gold, graphite), basic source hot magma, solidliquid &gas

3. The basic source of all minerals is the hot magma in the interior of the earth. 4. Physical properties of minerals

External crystal form - depend on internal arrangement, eg cube

Cleavage - Tendency to break in given direction, plane surface

Fracture - irregular not along cleavage plane

Lustre - metallic, silky, glossy, etc

Colour - Sometime because of impurities

Streak - same or different, malachite(green) : green streak, fluorite (purple or green) : white

Transparency - transparent, opaque, translucent

Structure - coarse, medium, fine etc

Hardness - 1. talc; 2. gypsum; 3. calcite; 4. fluorite; 5. apatite; 6. feldspar; 7. quartz; 8. topaz; 9. corundum;10. diamond, fingernail is 2.5 and glass or knife blade is 5.5

Specific gravity - ratio between the weight of a given object and the weight of an equal volume of water;[object weighed in air and then weighed in water and divide weight in air by the difference of the twoweights]

5. SOME MAJOR MINERALS AND THEIR CHARACTERISTIC Feldspar - [Silicon + oxygen] and [sodium, potassium, calcium, aluminium] (specific), Half of the earth’scrust, light cream to salmon pink (ceramic+ glass making)

Quartz - silica, insoluble, In granite and sand, white, radio and radar

Pyroxene - calcium, aluminum, magnesium, iron and silica, found in meteorites, green black [10%]

Amphibole - Aluminium, calcium, silica, iron, magnesium, green or black, asbestos industry, Hornblendeform of amphiboles [7%]

Mica - potassium, aluminium, magnesium, iron, silica, igneous and metamorphic rocks, electric [4%]

Olivine - Magnesium, iron and silica, jewelry, green, basaltic rocks.

Other - chlorite, calcite, magnetite, haematite, bauxite and barite

6. Metallic Minerals - Precious, Ferrous, Non- Ferrous, Non Metallic - Sulphur, phosphates and nitrates,cement

7. Acidic rock is rock that is siliceous (basalt is basic) (granite is acidic) 8. ROCKS - Petrology is science of rocks

(i) Igneous Rocks — magma and lava, primary rock, If cooled slowly at great depths, mineral grains maybe very large, Sudden cooling (at the surface) results in small and smooth grains, intermediate givesintermediate, Granite, gabbro(black), pegmatite, basalt, volcanic breccia and tuff

(ii) Sedimentary Rocks— decomposition and compaction, lithification, layers,

(a) mechanically formed — sandstone, conglomerate, limestone, shale, loess

(b) organically formed — geyserite, chalk, limestone, coal

(c) chemically formed — chert, limestone, halite, potash

(iii) Metamorphic Rocks — pressure, volume and temperature (PVT) changes, Arrangement of layers ofminerals foliation or lineation, alternate thin thick layers banding, foliated rocks and non-foliated, ExampleGneissoid, granite, syenite, slate, schist, marble, quartzite, diamond, Gneiss etc.

(a)dynamic metamorphism - pressure, breaking and crushing without any appreciable chemical changes

(b) thermal metamorphism - temperature, chemically alter and recrystallise, Contact metamorphism (Hightemperature, lava added, ) and regional metamorphism (tectonic shearing with high temperature andpressure)

9. ROCK CYCLE

GEOMORPHIC PROCESSES

1. vertically and horizontally moves earth crust, differences in the internal force created different landforms 2. Exogenic forces - gradation, degradtion & aggradation (filling up of basins ), land wearing forces 3. Endogenic forces - land building forces, 4. all organisms contribute to sustain the earth’s environment, humans excessive damage rapidly loosing

potential of land forms to sustain life5. GEOMORPHIC PROCESSES - exogenetic and enodgenetic forces causing changes in the configuration

of the surface, 6. Geomorphic agent - elements of nature capable of acquiring and transporting material, 7. Gravitational stresses and gravity - important geomorphic process and not a agent 8. ENDOGENIC PROCESSES - Internal energy because of radioactivity, rotational and tidal friction and

primordial heat from the origin of the earth, variations in geothermal gradients and heat flow produceduneven surfaces Diastrophism (slow) - elevate or build up portions of the earth’s crust,

(i) orogenic - mountain building, folding and faulting

(ii) epeirogenic - uplift or warping, submerge(west coast) and emerge (east coast), continental buildingprocess

(i) earthquakes - local relatively minor movements

(iv) plate tectonics - horizontal movements of crustal plates

Volcanism - lava, formation of dyke, etc

9. Exogenic geomorphic processes - denudation (Weathering, mass wasting/movements, erosion andtransportation)

10. The effects of most of the exogenic geomorphic processes are small and slow

WEATHERING

mechanical disintegration and chemical decomposition of rocks through the actions of various elements ofweather and climate, in-situ or on-site process,

Factors - climate, nature of slope, biotic factors

(i) Chemical :

Solution - dissolved in water or acids, calcium carbonate and calcium magnesium bicarbonate, limestone,salt

Carbonation - Reaction of carbonate and bicarbonate, feldspar, Calcium carbonates and magnesiumcarbonates are dissolved in carbonic acid and are removed in a solution without leaving any residueresulting in cave formation.

Hydration - Addition of water, takes water and expand, Calcium sulphate - gypsum, reversible and longcontinued

Oxidation - iron, manganese, sulphur, red colour iron turn to brown

Reduction - red iron to bluish green, all process go hand in hand

(ii) physical or mechanical :

Forces - gravitational forces, expansion forces, water pressure

Unloading and Expansion - Removal of overlying rock load, vertical load removed, expansion of outerlayer, Fractures parallel to the ground surface, Exfoliation domes results in case of round rock.

example : exfoliation (result but not a process, ) dome in granite rock near bhongir (Bhuvanagiri) town inAndhra Pradesh

Temperature Changes and Expansion - most effective in dry climates and high elevations where diurnaltemperature changes are drastic, granites, smooth surfaced and rounded small to big boulders called tors

Freezing, Thawing and Frost Wedging - high elevations in mid-latitudes where freezing and melting isoften repeated,

Salt Weathering - salt expand, thermal action, hydration and crystallisation,

granular disintegration / foliation - small crystal falls, areas with alternating wetting and drying conditions,Limestone, sandstone, shale, gneiss and granite

(iii) biological weathering : growth or movement of organisms. Burrowing and wedging by organisms likeearthworms, termites, rodents etc, disturbing vegetation, ploughing and cultivating soils, Decaying plant andanimal matter help in the production of humic, carbonic and other acids, plant roots

SIGNIFICANCE OF WEATHERING - formation of not only regolith and soils, erosion and massmovements, Biomes and biodiversity is result of forests (vegetation) and forests depend upon the depth ofweathering mantles, enrichment and concentrations of certain valuable ores of iron, manganese,aluminium, copper etc, which are of great importance for the national economy,

11. MASS MOVEMENTS - transfer the mass of rock debris down the slopes with help of gravity, air, water orice do not carry debris with them from place to place but on the other hand the debris may carry with it air,water or ice. Weathering is not a pre-requisite for mass movement Causes - removal of support from below, increase in gradient and height of slopes, overloading, overloading due to heavy rainfall, saturation and lubrication of slope materials, removal of material or loadfrom over the original slope surfaces, occurrence of earthquakes, explosions or machinery, excessivenatural seepage, heavy drawdown of water from lakes, reservoirs and rivers leading to slow outflow ofwater from under the slopes or river banks, indiscriminate removal of natural vegetation.

Slow Movements -

(i) Creep - moderately steep, soil covered slopes, Movement of materials is extremely slow, electricitypole, soil creep, talus creep, rock creep, rock-glacier creep,

(ii) solifluction - slow downslope flowing of soil mass or fine grained rock debris saturated or lubricatedwith water, moist temperate areas where surface melting of deeply frozen ground and long continued rainrespectively occur frequently.

Rapid Movements - humid climatic regions and occur over gentle to steep slopes

(i) earthflow - Movement of water-saturated clayey or silty earth materials down low-angle terraces orhillsides, steplike terraces, soft sedimentary rocks like shale or deeply weathered igneous rock

(ii) mudflow - absence of vegetation cover and with heavy rainfall, destructive engulfing roads, bridgesand houses, common in slopes of erupting or recently erupted volcanoes (Lahar),

(iii) avalanche - humid regions with or without vegetation cover and occurs in narrow tracks on steepslopes .Debris avalanche is similar to snow avalanche.

Landslides - rapid and perceptible movements, materials involved are relatively dry,

(i) Slump - debris has backward rotation with respect to the slope,

(ii) Debris slide - Rapid rolling without backward rotation,

(iii) Debris fall - free fall from a vertical or overhanging face

Mass movement in India -

(i) debris avalanches and landslides occur very frequently in the Himalayas

Reasons - tectonically active, mostly made up of sedimentary rocks and unconsolidated and semi-consolidated deposits, steep slope

(ii) Nilgiri and Western Ghat

Reasons - steeper with almost vertical cliffs, escarpments in the Western Ghats and Nilgiris, Mechanicalweathering due to temperature changes, heavy rainfall over short period

12. EROSION AND DEPOSITION - acquisition and transportation of rock debris, weathering not precondition, processes like erosion and transportation are controlled by kinetic energy, wind, running water,glaciers, waves and ground water, If the rocks are permeable and soluble and water is available only thenkarst topography develops. Coarser material deposited first

13. SOIL FORMATION - soil becomes adjusted to conditions of climate, landform and vegetation and willchange internally when these controlling conditions change Process of Soil Formation (Pedology soil science)

Weathering -> Material colonised by bacteria and other inferior plant bodies like mosses and lichens ->dead remain helps in humas accumulation -> Trees will start growing -> animal, birds -> burrowing, treeroots -> material becomes porous and spongelike with capacity to retain water and to permit the passage ofair and finally a mature soil, a complex mixture of mineral and organic products forms.

Soil-forming Factors

(i) parent material - passive, Nature and rate of weathering and depth of weathering mantle

(ii) topography - amount of exposure of surface, slope

(iii) climate - moisture and temperature, Excess of water helps in the downward transportation of soilcomponents through the soil (eluviation) and deposits the same down below (illuviation), Removal of silicafrom the soil is known as desilication(Heavy rain), dry climates high temperature, capillary action & waterevaporates leaving behind salts in the soil (hardpans.), tropical soils with higher temperatures show deeperprofiles and in the frozen tundra regions soils contain largely mechanically broken materials.

(iv) biological activity - adding organic matter, moisture retention, nitrogen etc, humas,

Humus accumulates in cold climates as bacterial growth is slow. With undecomposed organic matterbecause of low bacterial activity, layers of peat develop in sub-arctic and tundra climates.

Nitrogen fixation - bacteria and other soil organisms take gaseous nitrogen from the air and convert it intoa chemical form that can be used by plants. (Rhizobium)

(v) time - A soil becomes mature when all soil-forming processes act for a sufficiently long time developinga profile.

14.

LANDFORMS AND THEIR EVOLUTION

1. Landforms - small to medium tracts or parcels of surface (Several together landscape), change is shape,size, nature over time,

2. Stages of development of landmass - youth , mature, old3. Geomorphological Agent - erosional or destructional and depositional or constructional of landforms are

produced4. RUNNING WATER - humid region, mainly erosional land forms in steep slope and youthful stage of river,

Gentle the channel greater is the deposition (Lateral erosion of bank and formation of plains, depositionalforms also associates with the steep slope (small scale)Overland flow -

Flow as sheet on surface, sheet erosion, smaller and normal rills will (converted to gullies gradually-> network of valleys )

Early stage down cutting dominates (irregularities such as waterfalls and cascades will beremoved.)

middle stages cutting of bed, lateral erosion dominates basin lowered until it is almost completely flattened leaving lowland of faint relief (with some low

resistant remnants called monadnocks) plain formed as a result of stream erosion is called a peneplain (featureless plain )Linear flow - stream and rivers in valley

Characteristics of stages

Youth - V shaped valleys with no or very narrow flood plains, Stream divides broad and flat with marshes,swamp and lakes, Waterfall and rapids may exist, meanders may eventually entrenched

Mature - V shaped deep valleys, wider floodplains, meanders, flat and broad inter stream areas andswamps and marshes of youth disappear and the stream divides turn sharp, Waterfalls and rapidsdisappear.

Old - meander freely over vast floodplains, Divides are broad and flat with lakes,

Erosional Land forms

(i) Valleys -

gorge is a deep valley with very steep to straight sides, almost equal in width at its top as well as its bottom(sic), hard rocks

canyon is characterised by steep step-like side slopes, canyon is wider at its top than at its bottom(sic), horizontal bedded sedimentary rocks

Eg Valley of Kaveri river near Hogenekal, TN

(ii) Potholes - circular depressions, Over the rocky beds

(iii) Plunge pools - Pothole at the base of waterfall

(iv) Incised or Entrenched Meanders (hard to change) - very deep and wide meanders found cut in hardrocks, active lateral erosion, get entrenched into the rocks normally due to erosion or slow, continued upliftof the land, widen and deepen over time as deep gorges and canyons in hard rock areas

(v) River Terraces - marking old valley floor or floodplain levels, result of vertical erosion, Paired - sameelevation on either side, Unpaired - different elevation; typical in areas of slow uplift of land or water columnnot uniform

Depositional landforms

(i) Alluvial Fans - formed when streams flowing from higher levels break into foot slope plains of lowgradient, coarse load dumped and spread as a broad low to high cone shaped deposit, flowing over fansfans distributaries, humid areas show normally low cones with gentle slope, high cones with steep slope inarid and semi-arid climates.

(ii) Deltas - A river delta is a landform that forms from deposition of sediment carried by a river as the flowleaves its mouth and enters slower-moving or stagnant water. This occurs where a river enters an ocean

(iii) Floodplains - river bed made of river deposits is the active floodplain, floodplain above the bank isinactive floodplain (flood deposits (finer material) and channel deposits(Coarse material) )

(iv) Natural levees - along the banks of large rivers, low, linear and parallel ridges of coarse depositsalong the banks, large sized and high specific gravity materials get dumped

(v) Point bars / Meander bars - concave side of meanders, sediments deposited in a linear fashion byflowing waters along the bank, Uniform in profile and in width, contain mixed sizes of sediments

(vi) Meanders - Loop-like channel patterns, not a landform but is only a type of channel pattern, activedeposition along the concave bank, undercutting along the convex bank, concave bank- cut-off bank, cut-off due to erosion at the inflection points and are left as ox-bow lakes [check]

(i) propensity of water flowing over very gentle gradients to work laterally on the banks

(ii) unconsolidated nature of alluvial deposits making up the banks with many irregularities which can beused by water exerting pressure laterally

(iii) coriolis force acting on the fluid water deflecting it like it deflects the wind.

(vii) Braided Channels

Deposition and lateral erosion of banks are essential for the formation of braided pattern. When dischargeis less and load is more in the valley. Thread-like streams of water rejoin and subdivide repeatedly (Likebraid).

Example - Son and Gandak

5. Karst topography (Depositional + Erosional)

Any limestone or dolomitic region showing typical landforms produced by the action of groundwater throughthe processes of solution and deposition is called Karst topography. Named after the typical topographydeveloped in limestone rocks of Karst region in the Balkans adjacent to Adriatic sea

Erosional land forms

(i) Swallow holes - Small rounded sub rounded depression

(ii) Sinkhole - Funnel-shaped towards the bottom (doline is sometimes used to refer the collapse sinks)

(iii) valley sinks or Uvalas - When sink holes and dolines join together because of slumping of materialsalong their margins or due to roof collapse of caves, long, narrow to wide trenches

(iv) Grooves and Ridges or Lapies - most of the surface of the limestone is eaten away by these pits andtrenches, leaving it extremely irregular with a maze of points. (limestone pavements) (v) Caves - limestone dissolves and long and narrow to wide gaps called caves result. (Caves havingopenings at both the ends are called tunnels) [Calcium carbonate dissolves in carbonated water]

Depositional Land forms

(i) Stalactites - hang as icicles

(ii) Stalagmites - rise up from the floor of the caves [calcium carbonate is deposited when the watercarrying it in solution evaporates or loses its carbon dioxide]

6. GLACIERSEROSIONAL LANDFORMS

(i)Cirque - Often found at the heads of glacial valleys. They are deep, long and wide troughs or basins withvery steep concave to vertically dropping high walls at its head as well as sides. (cirque or tarn lakes whenmelted)

(ii) Horns and Serrated Ridges - Form through head ward erosion of the cirque walls. If three or moreradiating glaciers cut headward until their cirques meet, high, sharp pointed and steep sided peaks calledhorns form.

Example - highest peak in the Alps, Matterhorn and the highest peak in the Himalayas

(iii) Glacial Valleys/Troughs - U-shaped with broad floors and relatively smooth, and steep sides.Hanging valleys at an elevation on one or both sides of the main glacial valley (Hydropower Norway &Arunchal).

(iv) Fjords/Fiords - Very deep glacial troughs filled with sea water and making up shorelines (in highlatitudes)

Depositional land forms [Till is glacial origin and alluvium is fluvial origin.]

unassorted coarse and fine debris dropped by the melting glaciers is called glacial till

(i) Moraines - long ridges of deposits of glacial till. Terminal moraines are long ridges of debris depositedat the end (toe) of the glaciers. Lateral moraines form along the sides parallel to the glacial valleys. Glacialvalley flanked by lateral moraines is called medial moraine. Many valley glaciers retreating rapidly leave anirregular sheet of till over their valley floors. Such deposits varying greatly in thickness and in surfacetopography are called ground moraines.

(ii) Eskers - Long, narrow ridges formed due to melting of ice (Fluvio glacial) [due to water flow beneath theglaciers]

(iii) Outwash Plains - Plains at the foot of the glacial mountains. Covered with glacio-fluvial deposits.

(iv) Drumlins - Smooth oval shaped ridge-like features composed mainly of glacial till with some massesof gravel and sand (Basket of egg topography). Drumlins end facing the glacier called the stoss. Drumlinsgive an indication of direction of glacier movement [The drumlins form due to dumping of rock debris

beneath heavily loaded ice through fissures in the glacier]

7. WAVES AND CURRENTS ( high rocky coast (West Indian coast) and a low sedimentary coast (East Indiancoast) )

Erosional land forms

(i) Wave cut cliffs and terraces - are two forms usually found where erosion is the dominant shoreprocess.

(ii) Wave-cut terrace - Flat platforms occurring at elevations above the average height of waves

(iii) Sea caves - Erosion of cliffs

(iv) sea stacks - resistant masses of rock, originally parts of a cliff or hill (falling of cave roof)

DEPOSITIONAL LANDFORMS

(i) Beaches and Dunes

(ii) Offshore Bars - are elongate ridges and mounds of sand or gravel deposited beyond a shoreline bycurrents and waves. (iii) Barrier Bar - An off-shore bar which is exposed due to further addition of sand

Spits - Barrier bars get keyed up to one end of the bay (If joined barrier bar forms lagoon)

8. Winds

EROSIONAL LANDFORMS

Pediments - Gently inclined rocky floors close to the mountains at their foot with or without a thin cover ofdebris

Pediplains - high relief in desert areas is reduced to low featureless plains Bajadas - moderately sloping depositional plains located between pediments and playa.

Playas - Due to gradual deposition of sediment from basin margins, a nearly level plain forms at the centreof the basin. This plain is covered up by a shallow water body. Such types of shallow lakes are called asplayas. The playa plain covered up by salts is called alkali flats.

Deflation hollows - shallow depression formed due to soil gets blown out (deeper blow out forms caves)

Mushroom, Table and Pedestal Rocks - Many rock-outcrops in the deserts easily susceptible to winddeflation and abrasion are worn out quickly leaving some remnants of resistant rocks polished beautifully

Depositional Landforms

Sand Dunes

COMPOSITION AND STRUCTURE OF ATMOSPHERE

1. Composition Gases

Water Vapor

Dust particles - The higher concentration of dust particles is found in subtropical and temperate regionsdue to dry winds in comparison to equatorial and polar regions. (Water vapor condense around it )

2. STRUCTURE OF THE ATMOSPHERE Density is highest near the surface of the earth and decreases with increasing altitude

Troposphere - 8km near pole & 18 km near equator

Tropopause - -80 degree at equator and -45 degree at pole (Plane)

Stratosphere - Ozone (Super sonic jet) Mesosphere - Weather balloons (Meteor burns)

Ionosphere - 80-400 km, ions found here.

Thermosphere - is known as the exosphere. This is the highest layer but very little is known about it.

3. Karman line - Inner and outer atmosphere, 90 km

SOLAR RADIATION, HEAT BALANCE AND TEMPERATURE

1. Solar Radiation (Insolation) - Short wavelength [320 Watt/m2 in the tropics to about 70 Watt/m2 in thepoles.] Average the earth receives 1.94 calories per sq. cm per minute at the top of its atmosphere.

2. Aphelion - Earth is farthest from the sun (152 million km) on 4th July. [Summer in North]

Perihelion - On 3rd January, the earth is the nearest to the sun (147 million km) [Winter in north]

3. Summer Solstice - 21 June; Winter Solstice - 22 December; Equinox - 21 March and 23 September4. Days are always longer than nights at the equator (Refraction) 5. In the northern hemisphere the summer is slightly longer than the winter. 6. Factors affecting insolation

(i) the rotation of earth on its axis ( earth’s axis makes an angle of 66.5 degree with the plane of its orbitround the sun) [more effective]

(ii) the angle of inclination of the sun’s rays (slant rays are required to pass through greater depth of theatmosphere resulting in more absorption, scattering and diffusion)

(iii) the length of the day

(iv) the transparency of the atmosphere (Less effective)

(v) the configuration of land in terms of its aspect. (Less effective)

7. Scattering in troposphere gives color to the sky 8. Maximum insolation - Subtropical desert (Less cloudiness, hence not equator) [More on continent than

oceans] 9. Heating and cooling of atmosphere

Earth heated by insolation transmit heat in long wave radiation. This energy heats up the atmosphere frombelow. This process is known as terrestrial radiation.

Long wave radiation is absorbed by the atmospheric gases (GHG) [ atmosphere is indirectly heated by theearth’s radiation]

Conduction - air in contact with the land gets heated slowly and the upper layers in contact with the lowerlayers also get heated. [Two bodies unequal temperature, flow of energy]

Convection - Air in contact with the earth rises vertically in the form of currents & further transmission ofheat (vertical heating of the atmosphere) [convective transfer of energy is confined only to thetroposphere]

Advection - Horizontal movement of air [ In middle latitudes, most of dirunal (day and night) variation indaily weather are caused by advection alone, ‘loo’ is the outcome of advection process.]

10. Heat Budget

Earth as whole does not accumulate or loose heat (Maintains temperature) [Insolation = TerrestrialRadiation approx [amount of heat received in the form of insolation equals the amount lost by the earththrough terrestrial radiation]

Albedo of the earth - reflected amount of radiation

Surplus at equator and deficit at pole [surplus heat energy from the tropics is redistributed pole wards as aresult pole are not permanently frozen or tropic progressive heating]

11. TemperatureFactors Controlling Temperature Distribution

(i) the latitude of the place - Insolation varies hence temperature

(ii) the altitude of the place - Atmosphere heated up by terrestrial radiation [Normal lapse rate 6.5 degree/KM]

(iii) distance from the sea, the airmass circulation - Breezes

(iv) the presence of warm and cold ocean currents

(v) local aspects

12. Distribution of Temperature

Isotherm - Line joining equal temperature [No definite shape, generally parallel to latitude. More deviationin January than July, especially north (Land masses + Ocean current effect)]

More parallel in southern hemisphere [Ocean]

In January isotherm deviates to north in ocean.

In July mostly parallel to latitude

The highest range of temperature is more than 60° C over the north-eastern part of Eurasian continent.This is due to continentality. The least range of temperature, 3°C, is found between 20° S and 15° N

13. INVERSION OF TEMPERATURE Normal lapse rate is inverted.

The heat of the day is radiated off during the night, and by early morning hours, the earth is cooler than theair above.

Over polar areas, temperature inversion is normal throughout the year

Promotes stability in the lower layers of the atmosphere. The inversion takes place in hills and mountains due to air drainage. [Cold (Dense & heavy) air at the hillsand mountains, produced during night, flows under the influence of gravity. Protects plants from frostdamages.]

Plank’s law - hotter a body, the more energy it will radiate and shorter the wavelength of that radiation Specific heat - energy needed to raise the temperature of one gram of substance by one Celsius.

ATMOSPHERIC PRESSURE

1. Atmospheric pressureWeight of a column of air contained in a unit area from the mean sea level to the top of the atmosphere.

Pressure decrease with height.

Vertical gradient of pressure [Balanced by gravity, Hence no upward winds] is much higher than horizontal.

Lower atmosphere the pressure decreases rapidly with height [1 mb / 10 m]

Isobars - lines connecting places having equal pressure. [To eliminate the effect of altitude on pressure, itis measured at any station after being reduced to sea level]

2. World Distribution of Sea Level Pressure Equatorial low - Near equator the sea level pressure is low/ Doldrums

Subtropical highs - Along 30° N and 30° S high-pressure / Horse latitude

Sub polar low - 60° N and 60° S, Low-pressure belts

Polar high - Near the poles the pressure is high [Oscillate with the apparent movement of the sun. In the northern hemisphere in winter theymove southwards and in the summer northwards]

3. Forces Affecting the Velocity and Direction of WindPressure Gradient Force [ROC of pressure wrt distance] - strong where the isobars are close to eachother and is weak where the isobars are apart. Perpendicular to isobar.

Frictional Force - Influence upto 3 km, greatest at surface minimum at ocean

Coriolis Force

Due to rotation of earth.

Directly proportional to angle on latitude.

Max at pole absent at equator.

Acts perpendicular to pressure gradient force ( low-pressure areas the wind blows around it. At the equator,the Coriolis force is zero and the wind blows perpendicular to the isobars. Low pressure gets filled ratherthan intensifying. Hence tropical cyclones are not formed near the equator).

Right in north, Left in south

Gravitational force - acts downward.

4. Geostrophic wind - When isobars are straight and when there is no friction, the pressure gradient force isbalanced by the Coriolis force and the resultant wind blows parallel to the isobar.

5. Cyclonic circulation - wind circulation around a low.

Anti cyclonic circulation - wind circulation around a high. Generally, over low pressure area the air will converge and rise

Over high pressure area the air will subside from above and diverge at the surface

6. Pattern of planetary winds largely depends on(i) latitudinal variation of atmospheric heating

(ii) emergence of pressure belts

(iii) the migration of belts following apparent path of the sun

(iv) the distribution of continents and oceans

(v) the rotation of earth

Cell - circulations from the surface upwards and vice-versa

Hadley cell - Tropics/ ITCZ/ Doldrums

Ferrel cell - Suntropic/ STH

Polar Cell - Pole/ SPH

El Nino event is closely associated with the pressure changes in the Central Pacific and Australia. Thischange in pressure condition over Pacific is known as the southern oscillation Only El Nino == Warm water in Eastern Pacific + Cold water in Western Pacific. Only SO == Low-pressureover Eastern Pacific + High-pressure over Western Pacific ENSO = (Warm water in Eastern Pacific + Low-pressure over Eastern Pacific) + (Cold water in WesternPacific + High-pressure over Western Pacific) (EQUINOO: oscillation of warm water and atmospheric pressure between Bay of Bengal and Arabian Sea

El Niño Modoki is associated with strong anomalous warming in the central tropical Pacific and cooling inthe eastern and western tropical Pacific. [Double walker cell]

In some years the trade winds can become extremely strong, and an abnormal accumulation of cold watercan occur in the central and eastern Pacific. This event is called a La Niña

Permanent winds

Trade Winds - STH to ELPB

Westerlies

Polar Easterlies

7. Local Winds

Land and Sea Breezes - Day sea breeze, Night Land breeze

Mountain and Valley Winds - Day valley breeze, Night mountain wind. [The cool air, of the high plateausand ice fields draining into the valley is called katabatic wind]

Warm wind occurs on the leeward side [descends down the leeward side of the slope the dry air getswarmed up by adiabatic process.]

8. Air Masses Large body of air having little horizontal variation in temperature and moisture

The homogeneous surfaces, over which air masses form, are called the source regions

Five major source region (i) Warm tropical and subtropical oceans

(ii) The subtropical hot deserts

(iii) The relatively cold high latitude oceans

(iv) The very cold snow covered continents in high latitudes

(v) Permanently ice covered continents in the Arctic and Antarctica

Types of air masses

(i) Maritime tropical (mT)

(ii) Continental tropical (cT)

(iii) Maritime polar (mP)

(iv) Continental polar (cP)

(v) Continental arctic (cA)

Tropical air masses are warm and polar air masses are cold

9. Fronts Boundary zone when two air masses meet

Frontogenesis - Formation of front

Types

(a) Cold

(b) Warm

(c) Stationary

(d) Occlude - If an air mass is fully lifted above the land surface The fronts occur in middle latitudes and are characterised by steep gradient in temperatureand pressure.

10. Middle latitude / Extra Tropical Cyclone/ Temperate cyclone Mid and High latitude

Form along polar front

In the northern hemisphere, warm air blows from the south and cold air from the north of the front

When the pressure drops along the front, the warm air moves northwards and the cold air move towards,south setting in motion an anticlockwise cyclonic circulation.

The warm air glides over the cold air and a sequence of clouds appear over the sky ahead of the warmfront and cause precipitation.

The cold front approaches the warm air from behind and pushes the warm air up. Cumulonimbus clouds occur only along the cold front. Hence it is the region that experiences short durationrainfall associated with thunderstorms The cold front moves faster than the warm front ultimately overtaking the warm front.

Tropical Cyclones

Originate over oceans in tropical area.

Large scale destruction caused by violent winds, very heavy rainfall and storm surges.

Known as

Cyclones in the Indian Ocean

Hurricanes in the Atlantic

Typhoons in the Western Pacific and South China Sea

Willy-willies in the Western Australia.

conditions favourable

i) Large sea surface with temperature higher than 27° C

(ii) Presence of the Coriolis force

(iii) Small variations in the vertical wind speed

(iv) A pre-existing weaklow-pressure area or low-level-cyclonic circulation

(v) Upper divergence above the sea level system.

The energy that intensifies the storm, comes from the condensation process in the towering cumulonimbusclouds [On land moisture supply cut off, Landfall point]

The cyclones, which cross 20 degree N latitude generally, recurve and they are more destructive. Eye is high pressure center [Pressure defect] (Due to subsiding warm air, No rainfall here,Clear sky)

Difference in tropical and extra tropical

Extra Tropical (30-40 degree latitude)

Clear frontal System

cover a larger area and can originate overthe land and sea

affects a much larger area

Less wind velocity and less destructive

move from west to east (Gradual andpredictable)

Dynamically induced

Tropical (8-20 degree latitude)

Frontal system not present

originate only over the seas and on reaching theland they dissipate.

Affects less area

Wind velocity higher and much destructive

move from east to west (unpredictable)

Thermally induced

11. Thunderstorms and Tornadoes

severe local storms

occurring over a small area but are violent Thunderstorms

caused by intense convection on moist hot days [well-grown cumulonimbus cloud]

Thunder, Lightning, Hailstorm [In case of insufficient moisture, dry storm] Tornadoes

Thunderstorms sometimes spiralling wind descends like a trunk of an elephant with great force, with verylow pressure at the center. Tornadoes generally occur in middle latitudes because of convergence of warmand cold air masses.

The tornado over the sea is called water spouts.

heat energies are converted into kinetic energy and restless atmosphere again stables

WATER IN THE ATMOSPHERE

1. Exchange of water through - evaporation, transpiration, condensation and precipitation. 2. Absolute humidity - Actual amount of water vapor present in the atmosphere. 3. Relative humidity - percentage of moisture present in the atmosphere as compared to its full capacity at a

given temperature. [Greater over ocean] [warm air can hold more water vapor than cool air, relativehumidity falls when the temperature rises]

4. Dew point - The temperature at which saturation occurs in a given sample of air. 5. Latent heat of vapourisation - The temperature at which the water starts evaporating. [greater the

movement of air, the greater is the evaporation (replacement of saturated layer)] 6. Increase in temperature increases water absorption and retention capacity 7. Condensation - Loss of heat (Direct condensation to solid state sublimation)8. Hygroscopic condensation nuclei - cooling around very small particles 9. Condensation takes place

(i) when the temperature of the air is reduced to dew point with its volume remaining constant

(ii) when both the volume and the temperature are reduced

(iii) when moisture is added to the air through evaporation

10. Type of Condensation Dew - clear sky, calm air, high relative humidity and cold and long nights (dew point > the freezing point)

Frost - condensation takes place below freezing point

Fog & Mist - Temperature of an air mass containing a large quantity of water vapour falls all of a sudden.Condensation on dust particles. (Mist contains more moisture than fog, Found in mountain region)

Clouds

(i) Cirrus - At high altitude, white, feathery appearance, Thin & detached (8k-12k M)

(ii) Cumulus - Like cotton wool, Flat base, Exist in patches, Scattered (4k-8k M)

(iii) Stratus - Layered cloud, covers large portion, due to loss of heat or the mixing of air masses withdifferent temperatures

(iv) Nimbus - Black or dark gray, Near surface of earth, Dense & opaque to sun rays, Mass of thick vapor

High clouds – cirrus, cirrostratus, cirrocumulus

Middle clouds – altostratus and altocumulus

low clouds – stratocumulus and nimbostratus

Cumulus and cumulonimbus - clouds with extensive vertical development

11. Precipitation - Release of moisture. Rain, Snow (Hexagonal crystal), Hail and Sleet (Temperature isgreater than freezing point above and below there is Subfreezing layer)

12. Types of Rainfall Convectional

Heated air becomes light and rise up in convection current. As it rises expand and looses heat,condensation takes place. Cumulus cloud formed. With thunder and light heavy rainfall not lasting long,Common in summer/ equatorial part & interior of continents.

Orographic or relief

Saturated air mass comes across mountain, forced to ascend and as it rises it expands temperature fallsand moisture is condensed. Windward slopes receive greater rainfall [On other side (rain-shadow area) itdescent temperature rises and capacity to hold moisture rain-shadow area].

Cyclonic or frontal - Occurs during cyclone

13. World Distribution of Rainfall From equator to pole rainfall decreases

Coastal region receives more rainfall

Rainfall is more over ocean than land

Between the latitudes 35 and 40 N and S of the equator, the rain is heavier on the eastern coasts and goeson decreasing towards the west

Between 45 and 65 N and S of equator, due to the westerlies, the rainfall is first received on the westernmargins Equatorial belt and in the western parts of cool temperate regions have even distributionof rainfall throughout the year

WORLD CLIMATE AND CLIMATE CHANGE

1. KOEPPEN ’S SCHEME OF CLASSIFICATION OF CLIMATE It is an empirical classification based on mean annual and mean monthly temperature and precipitation data

The capital letters : A,C, D and E delineate humid climates and B dry climates.

Climatic groups are subdivided into types, designated by small letters.

f - no dry season, m - monsoon climate, w- winter dry season and s - summer dry season

The small letters a, b, c and d refer to the degree of severity of temperature

The B- Dry Climates are subdivided using the capital letters S for steppe or semi-arid and W for deserts.

Tropical Wet Climate (Af)

Near equator

Significant rainfall every month & thunder shower in afternoon

Max temperature of day 30 min 20

Tropical evergreen forest

Tropical Monsoon Climate (Am)

Over Indian sub continent, North Eastern part of South America and Northern Australia

Heavy rainfall in summer & winter is dry

Tropical Wet and Dry Climate (Aw)

occurs north and south of Af type climate regions

Borders with dry climate on the western part of the continent and Cf or Cw on the eastern part.

The wet season is shorter and the dry season is longer with the drought being more severe

Temperature is high throughout the year and diurnal ranges of temperature are the greatest in the dryseason.

Deciduous forest and tree-shredded grasslands

Subtropical steppe (BSh) and subtropical desert (BWh)

Located in the transition zone between humid and dry climates

BSh - sparse grasslands

Fog is common in coastal deserts bordering cold currents.

The highest shade temperature of 58° C was recorded at Al Aziziyah, Libya

Warm Temperate (Mid-Latitude) Climates-C

climates extend from 30° - 50° of latitude

mainly on the eastern and western margins of continents

Humid Subtropical Climate (Cwa)

Occurs poleward of Tropic of Cancer and Capricorn.

The climate is similar to Aw climate except that the temperature in winter is warm.

Mediterranean Climate (Cs)

occurs around Mediterranean sea

Hot, dry summer and mild, rainy winter.

Humid Subtropical (Cfa) Climate

Lies on the eastern parts of the continent in subtropical latitude.

Unstable and cause rainfall throughout the year.

Eastern United States of America, southern and eastern China, southern Japan, northeastern Argentina,coastal south Africa and eastern coast of Australia.

Thunderstorms in summer and frontal precipitation in winter

summer is around 27°C, and in winter it varies from 5°-12° C.

Marine West Coast Climate (Cfb)

Located poleward from the Mediterranean climate on the west coast of the continents.

Due to marine influence, the temperature is moderate and in winter, it is warmer than for its latitude

Precipitation throughout the year

Cold Climate with Humid Winters (Df)

Occurs poleward of marine west coast climate and mid latitude steppe

The winters are cold and snowy.

The annual ranges of temperature are large.

Cold Climate with Dry Winters (Dw)

Mainly over Northeastern Asia

Tundra climate (ET)

low growing mosses, lichens and flowering plants

permafrost

short growing season and water logging support only low growing plants.

Ice cap climate (EF)

occurs over interior Greenland and Antartica

Even in summer, the temperature is below freezing point.

Receives very little precipitation

Highland Climates (H)

Governed by topography

Large changes in mean temperature occur over short distances

2. Greenhouse gases - The gases that absorb long wave radiation3. During the 1930s, severe drought occurred in southwestern Great Plains of the United States, described as

the dust bowl 4. Sunspots are dark and cooler patches in a region called the photosphere on the sun which increase and

decrease in a cyclical manner. 5. According to some meteorologists, when the number of sunspots increase, cooler and wetter weather and

greater storminess occur. A decrease in sunspot numbers is associated with warm and drier conditions. 6. A Milankovitch cycle is a cyclical movement related to the Earth’s orbit around the Sun. There are three of

them: eccentricity, axial tilt, and precession (Wobble like a top). According to the Milankovitch Theory, these

three cycles combine to affect the amount of solar heat that’s incident on the Earth’s surface andsubsequently influence climatic patterns.

WATER (OCEANS)

1. Hydrological cycle

2.

3. RELIEF OF THE OCEAN FLOOR

Major Relief Features

Continental Shelf

Shallowest part

Average gradient 1 degree or less

Ends at shelf break (Average width 80 km)

Very narrow along coasts of Chile, the west coast of Sumatra

Siberian shelf in the Arctic Ocean, the largest in the world (1,500 km in width)

Massive sedimentary deposits, become the source of fossil fuels.

Continental Slope

Connects ocean basin and continental shelf

Depth 200-3000m

Canyons and trenches are observed

Deep Sea Plain

Flattest and smoothest regions of the world

Covered with fine grained sediments like clay and silt

Oceanic Deeps or Trenches

Deepest part of ocean

57 deeps, 32 are in the Pacific Ocean; 19 in the Atlantic Ocean and 6 in the Indian Ocean.

Minor Relief Features

Mid-Oceanic Ridges

Iceland, a part of the mid-oceanic ridges is an example of sea mount ( Seamounts are volcanic in origin)

Submarine Canyons

Hudson Canyon is the best known submarine canyon

Guyots

flat topped seamount

Atoll

Low islands found in the tropical oceans consisting of coral reefs surrounding a central depression

4. TEMPERATURE OF OCEAN WATERS Factors Affecting Temperature Distribution

Latitude - Decreases from the equator towards the poles

Average temperature of surface water 27 degree

decrease of temperature with increasing latitude is generally 0.5°C per latitude.

The highest temperature is not recorded at the equator but slightly towards north of it.

Unequal distribution of land and water - Northern ocean warmer than southern (More land) Prevailing wind - Onshore winds pile up warm water near the coast (Offshore winds - up welling of coldwater) Ocean currents - Warm ocean increase temperature, cold ocean decrease temperature

The enclosed seas - low latitudes higher temperature than the open seas; In the high latitudes lowertemperature than the open seas.

Vertical Distribution of Temperature

About 90 per cent of the total volume of water is found below the thermocline

5. SALINITY OF OCEAN WATERS Salinity of 24.7 ppt has been considered as the upper limit to demarcate ‘brackish water

Highest salinity in water bodies Lake Van in Turkey (330), Dead Sea (238), Great Salt Lake (220)

Factors affecting ocean salinity

Depend mainly on evaporation and precipitation. Surface salinity influenced in coastal regions by the fresh water flow from rivers, and in polar regions by theprocesses of freezing and thawing of ice

Winds for transferring salinity

Ocean current

HORIZONTAL DISTRIBUTION OF SALINITY

Salinity decreases from 35 to 31 on the western parts of the northern hemisphere because of the influx ofmelted water from the Arctic region.

It gradually decreases towards the north.

The North Sea, in spite of its location in higher latitudes, records higher salinity due to more saline waterbrought by the North Atlantic Drift.

Baltic Sea records low salinity due to influx of river waters in large quantity.

The Mediterranean Sea high evaporation & high salinity

Very low in Black Sea due to enormous fresh water influx by rivers Bay of Bangal is less saline than Arabic sea The highest salinity is recorded between 15° and 20° latitudes Maximum salinity (37 o/oo) is observed between 20°N and 30° N and 20° W - 60° W.

VERTICAL DISTRIBUTION OF SALINITY

The lower salinity water rests above the higher salinity dense water

Salinity, generally, increases with depth and there is a distinct zone called the halocline, where salinityincreases sharply.

MOVEMENTS OF OCEAN WATER

1. The horizontal motion refers to the ocean currents and waves.2. Ocean water is raised up and falls down twice a day ( The vertical motion refers to tides) 3. WAVES

Wind provides energyEnergy is released on shorelines.when the depth of water is less than half the wavelength of the wave, the wave breaksGrow larger as they absorbed energy from windA wave’s size and shape reveal its origin.Slow and steady waves originate from far away placesWaves travel because wind pushes the water body in its course while gravity pulls the crests of the

waves downwardThe actual motion of the water beneath the waves is circular

4. TIDES

Mainly due to the attraction of the sun (lesser) and the moon (greater)Centrifugal force, which is the force that acts to counter balance the gravity.‘Tide-generating’ force is the difference between the gravitational attraction of the moon and the

centrifugal force.When the tide is channeled between islands or into bays and estuaries they are called tidal

currents.The highest tides in the world occur in the Bay of Fundy in Nova Scotia, Canada The shape of bays and estuaries along a coastline can also magnify the intensity of tides.

Tides based on Frequency

Semi-diurnal tide - two high tides and two low tides each day

Diurnal tide - only one high tide and one low tide during each day. Mixed tide - Tides having variations in height are known as mixed tides.

Tides based on the Sun, Moon and the Earth Positions

Spring tides - When the sun, the moon and the earth are in a straight line, the height of the tide will behigher. Occur twice a month, one on full moon period and another during new moon period.

Neap tides - Sun and moon are at right angles to each other and the forces of the sun and moon tend tocounteract one another.

Once in a month, when the moon’s orbit is closest to the earth (perigee), unusually high and low tides occur

Two weeks later, when the moon is farthest from earth (apogee), the moon’s gravitational force is limitedand the tidal ranges are less

Ebb - The time between the high tide and low tide, when the water level is falling

Flow or Flood - The time between the low tide and high tide, when the tide is rising

Importance of Tides

Ocean currents Helps the navigators and fishermen plan their activities.Tidal heights are very important, especially harbours near rivers and within estuaries having shallow

‘bars’ at the entrance, which prevent ships and boats from entering into the harbour.

Helpful in desilting the sediments and in removing polluted water from river estuaries.Used to generate electrical power (in Canada, France, Russia, and China). A 3 MW tidal power

project at Durgaduani in Sunderbans of West Bengal is under way.

5. Primary forces that influence the currents (Initiate movement of water)

(i) heating by solar energy (Expands water hence high height at equator)

(ii) wind

(iii) gravity

(iv) coriolis force (Formation of Gyres - large circular currents)

Surface currents constitute about 10 per cent of all the water in the ocean, these waters are the upper 400m of the ocean

Deep water currents make up the other 90 per cent of the ocean water.

The air circulation over the oceans in the middle latitudes is mainly anticyclonic (more pronounced in thesouthern hemisphere than in the northern hemisphere)

The mixing of warm and cold currents help to replenish the oxygen and favor the growth of planktons, theprimary food for fish population.

LIFE ON THE EARTH

1. Ecological systems - The interactions of a particular group of organisms with abiotic factors within aparticular habitat resulting in clearly defined energy flows and material cycles on land, water and air.

2. Ecosystem is a functional unit. It includes environment (biotic+ abiotic) and ecology(how living organismsinteract with each other and the environment).

3. A biome is a plant and animal community that covers a large geographical area. 4. Resultant transfer of energy from one level to another is known as the food-chain 5. Flow of energy - Transfer of energy that occurs during the process of a foodchain from one level to

another.6. Food web - interconnecting network of species. 7. In a grazing food-chain, the first level starts with plants as producers and ends with carnivores as

consumers at the last level. There is a loss of energy at each level which may be through respiration,excretion or decomposition

8. Bioms

9. Biogeochemical Cycles

cyclic movements of chemical elements of the biosphere between the organism and the environment.

Out of total solar radiation only 0.1 % used for photosynthesis. In the gaseous cycle, the main reservoir of nutrients is the atmosphere and the ocean.

In the sedimentary cycle, the main reservoir is the soil and the sedimentary and other rocks of the earth’scrust.

10. The Water Cycle - circulation of water in solid, liquid or gaseous form referred to as the water or hydrologiccycle

11. The Carbon Cycle The Oxygen CycleThe biosphere contains over half a million carbon compounds in them.Fixation of carbon dioxide from the atmosphere through photosynthesis.

Conversion results in the production of carbohydrate, glucose.Some of the carbohydrates are utilised directly by the plant itself. During this process, more carbon

dioxide is generated and is released through its leaves or roots.The remaining carbohydrates not being utilised by the plant become part of the plant tissue.Plant tissues are either being eaten by the herbivorous animalsThe herbivores convert some of the consumed carbohydrates into carbon dioxide for release into

the air through respirationThe carbohydrates that are decomposed by the micro-organisms then get oxidised into carbon di

oxide 12. Oxygen Cycle

Oxidation of carbohydrates with the release of energy, carbon dioxide and water.

13. The Nitrogen Cycle

Succession - secondary forest species overtakes the native species changing the original forest structure.1. Only a few types of organisms like certain species of soil bacteria and blue green algae are capableof utilising it directly in its gaseous form.2. Ninety per cent of fixed nitrogen is biological ( converted into ammonia or other molecules availableto living organisms)3. Nitrogen can also be fixed in the atmosphere by lightning and cosmic radiation.4. Dead plants and animals, excretion of nitrogenous wastes are converted into nitrites by the action ofbacteria present in the soil. [Then nitrite converted to nitrate]5. Denitrification - There are types of bacteria capable of converting nitrates into free nitrogen

14.

BIODIVERSITY AND CONSERVATION

1. 99 per cent of the species that have ever lived on earth are extinct 2. As one approaches the polar regions, one finds larger and larger populations of fewer and fewer species. 3. Biodiversity

(i) Genetic diversity - variation of genes within species

(ii) Species diversity - It relates to the number of species in a defined area

(iii) Ecosystem diversity - The broad differences between ecosystem types and the diversity of habitatsand ecological processes occurring within each ecosystem type constitute the ecosystem diversity.

4. Importance of Biodiversity Ecological Role of Biodiversity - Species capture and store energy, produce and decompose organicmaterials, help to cycle water and nutrients throughout the ecosystem, fix atmospheric gases and helpregulate the climate

Economic Role of Biodiversity - food crops, livestock, forests, fish, medicinal resources, etc

Scientific Role of Biodiversity - each species can give us some clue as to how life evolved and willcontinue to evolve.

5. Species which are not the natural inhabitants of the local habitat but are introduced into the system, arecalled exotic species.

6. IUCN Classification

7. Zenkeria Sebastinei — a critically endangered grass in Agasthiyamalai peak (India) 8. Humbodtia decurrens Bedd — highly rare endemic tree of Southern Western Ghats (India)

9. Areas rich in species diversity are called hotspots of diversity

Miscellaneous

1. Phases of sun

2. All parallel circles from the equator up to the poles are called parallels of latitudes. 3. (i) Tropic of Cancer (23½° N) in the Northern Hemisphere. (ii) Tropic of Capricorn (23½° S) in the Southern

Hemisphere. (iii) Arctic Circle at 66½° north of the equator. (iv) Antarctic Circle at 66½° south of theequator.

4. Torrid Zone - Area between tropic of Cancer and Capricorn 5. Block Mountains are created when large areas are broken and displaced vertically. The uplifted blocks are

termed as horsts and the lowered blocks are called graben. The Rhine valley and the Vosges mountain inEurope are examples of such mountain systems.

6. Hundru falls in the Chhotanagpur plateau on the river Subarnarekha 7. The main mineral constituents of the continental mass are silica and alumina. It is thus called sial (si-silica

and al-alumina). The oceanic crust mainly consists of silica and magnesium; it is therefore called sima 8. Nitroge > Oxygen > Argon > Carbon dioxide > Neon 9. Aeroplane fly in stratosphere (as per NCERT)

10. On the moon there is no air and hence no air pressure. Astronauts have to wear special protective spacesuits filled with air when they go to the moon. If they did not wear these space suits, the counter pressureexerted by the body of the astronauts would make the blood vessels burst.

11. Ocean > Icecap > Groundwater > Fresh water lakes > Inland salt lakes > Soil moisture > Atmosphere 12. Mediterranean trees adapt themselves to dry summers with the help of their thick barks and wax coated

leaves which help them reduce transpiration. 13. The temperate grasslands of North America are known as the Prairies 14. The Prairies are also known as the “Granaries of the world,” due to the huge surplus of wheat production. 15. The temperate grasslands of South Africa are called the velds 16. The National Highway 1A connects Leh to Kashmir Valley through the Zoji la Pass. 17. CITES (the Convention on International Trade in Endangered Species of Wild Fauna and Flora) is an

international agreement between governments. It aims to ensure that international trade in specimens ofwild animals and plants does not threaten their survival.

18. Brazil is the largest producer of high grade iron-ore in the world. 19. China, Malaysia and Indonesia are among the world’s leading tin producers. China also leads in production

of lead, antimony and tungsten. 20. The countries with large deposits of iron ore are Russia, Ukraine, Sweden and France. 21. Chile and Peru are leading producers of copper. Brazil and Bolivia are among the world’s largest producers

of tin. South America also has large deposits of gold, silver, zinc, chromium, manganese, bauxite, mica,platinum, asbestos and diamond. Mineral oil is found in Venezuela, Argentina, Chile, Peru and Columbia.

22. Africa is world’s largest producer of diamonds, gold and platinum.23. Australia is the largest producer of bauxite in the world. 24. Copper: It is mainly produced in Rajasthan, Madhya Pradesh, Jharkhand, Karnataka and Andhra Pradesh. 25. Kolar in Karnataka has deposits of gold in India 26. Coal is refereed as Buried Sunshine27. In India, geothermal plants are located in Manikaran in Himachal Pradesh and Puga Valley in Ladakh. 28. Gulf of Kachchh in India have huge tidal mill farms. 29. Shifting cultivation is known by different names in different parts of the world Jhumming - North-East India

Milpa -Mexico Roca - Brazil. Ladang - Malaysia 30. Standard Meridian of India (82°30'E) passing through Mirzapur (in Uttar Pradesh) is taken as the standard

time for the whole country. 31. Luni is the only large river in Indian desert 32. Although the total amount of winter rainfall locally known as ‘mahawat’ is small, they are of immense

importance for the cultivation of ‘rabi’ crops. 33. whenever the axis shifts closer to the Himalayas, there are longer dry spells in the plains, and widespread

rain occur in the mountainous catchment areas of the Himalayan rivers. 34. depressions form at the head of the Bay of Bengal and cross over to the mainland. The depressions follow

the axis of the “monsoon trough of low pressure 35. Sarpgandha - Used to treat blood pressure; it is found only in India36. India is the only country in the world that has both tigers and lions. 37. Contour ploughing reduces spoil erosion 38. Tamil Nadu is the first state in India which has made rooftop rainwater harvesting structure compulsory to all

the houses across the state. 39. In India, this primitive form of cultivation is called ‘Bewar’ or ‘Dahiya’ in Madhya Pradesh, ‘Podu’ or ‘Penda’

in Andhra Pradesh, ‘Pama Dabi’ or ‘Koman’ or Bringa’ in Odisha, ‘Kumari’ in Western Ghats, ‘Valre’ or‘Waltre’ in South-eastern Rajasthan, ‘Khil’ in the Himalayan belt, ‘Kuruwa’ in Jharkhand, and ‘Jhumming’ inthe North-eastern region.

40. The ‘slash and burn’ agriculture is known as ‘Milpa’ in Mexico and Central America, ‘Conuco’ in Venzuela,‘Roca’ in Brazil, ‘Masole’ in Central Africa, ‘Ladang’ in Indonesia, ‘Ray’ in Vietnam

41. Rubber is an equatorial crop, but under special conditions, it is also grown in tropical and sub-tropicalareas.

42. In igneous and metamorphic rocks minerals may occur in the cracks, crevices, faults or joints. The smalleroccurrences are called veins and the larger are called lodes.

43. Kepler's second law of planetary motion states that a line between the sun and the planet sweeps equalareas in equal times.

44. The Moon completes one revolution relative to the fixed stars in about 27.32 days (a sidereal month) andrelative to the Sun in about 29.53 days (a synodic month).

45. Earth's magnetic field reduces atmospheric escape by protecting the atmosphere from solar wind. 46. Sulphurous smog is also called London smog (first formed in London due to industrial revolution). 47. Photochemical smog is also known as summer smog or Los Angeles smog. 48. Halos (22° halo) are caused by both refraction and reflection of sunlight by ice crystals in cirrus clouds 49. Earth is a good conductor of electricity but is electrically neutral. 50. The most lightning activity on Earth is seen on the shore of Lake Maracaibo in Venezuela. 51. During strong El Nino years, strong hurricanes occur in the eastern Pacific. This is due to the accumulation

of warm waters in the eastern Pacific due to weak Walker Cell. 52. Polar vortex is closely associated with jet streams (Rossby waves). 53. The Walker circulation (Walker cell) is caused by the pressure gradient force that results from a high

pressure system over the eastern Pacific Ocean, and a low-pressure system over Indonesia. 54. El Niño brings drought to the western Pacific, rains to the equatorial coast of South America, and

convective storms and hurricanes to the central Pacific. 55. Bermuda is coral island 56. The Lakshadweep and Maldives are coral islands and Mauritius and the Reunion Islands are of volcanic

origin 57. Phytoplanktons consume too much oxygen during nights, thus depriving other marine organisms of oxygen.58. Sargasso Sea is a Gyre. [North Atlantic] 59. Doldrums are calm regions facilitating the backward movement of water [Equatorial counter current] 60. circulation of water in the northern part of the Indian ocean is clockwise during summer season.

[Anticlockwise in northern]. 61. Kerala's placer deposits contain 90 per cent of the world's monazite reserves 62. USA has signed the UNCLOS but has not ratified it. 63. The Spratly Islands and Paracel Islands are two of the most contested areas in the South China Sea. 64. Mponeng gold mine (deepest mine) 65. The velocity of the P-waves in Solids > Liquids > Gases 66. S-waves cannot pass through fluids (liquids and gases) as fluids do not support shear stresses. 67. North Magnetic Pole of the Earth is the south pole of its magnetic field 68. Magnetic dip, dip angle, or magnetic inclination is the angle made with the horizontal by the Earth's

magnetic field lines. 69. Magnetosphere protect earth from the charged particles of the solar wind and cosmic rays70. A Van Allen radiation belt is a zone of energetic charged particles, most of which originate from the solar

wind, that are captured by and held around a planet by that planet's magnetic field. 71. Venus lacks a magnetic field 72. If the height of the mountains is considered from the ocean floor, Mauna Kea (9140 m), would be the

highest mountain. It is a dormant volcanic mountain in the Hawaii hotspot volcanic chain. 73. Caledonian mountain - Appalachians, Aravallis, Mahadeo 74. Hercynian mountains - Vosges and the Black Forest, Altai, Tien Shan mountains of Asia, Ural Mountains 75. Alpine system - Rockies, Atlas and Himalaya 76. Longest mountain - The Andes > The Rockies > Ural Mountains > Atlas > Himalayas 77. The highest known mountain on any planet in the Solar System is Olympus Mons on Mars (~26 km in

elevation). It is also the highest active volcano in the Solar System. 78. A lahar is a violent type of mudflow or debris flow 79. Volcano - USA > Russia > Indonesia > Iceland > Japan80. Wadati–Benioff zone: Earthquakes along the Convergent boundary [Deep focus] 81. Sindri Lake (Allah Bund) - Formed because of earthquake 82. With the decrease in speed, the height of the tsunami wave grows. A tsunami which was imperceptible in

deep water may grow to many metres high, and this is called the ‘shoaling’ effect [Bigger wave withshallower water]

83. Bird’s Foot Delta - The currents and tides are weak in such areas. [Mississippi ]84. Estuaries - River appears to be submerged. Ideal sites for fisheries, ports and industries 85. Cuspate Delta - pointed delta generally formed along strong coasts and is subjected to strong wave action

[Tiber river on the west coast of Italy]

Tertiary or Local Winds

1. Loo - In the plains of northern India and Pakistan, sometimes a very hot and dry wind blows from the westin May and June, usually in the afternoons. It is known as loo. (Cause sunstroke)

2. Foehn or Fohn - Foehn is a hot wind of local importance in the Alps. The wind helps animal grazing bymelting snow and aids the ripening of grapes.

3. Chinook - Foehn like winds in USA and Canada move down the west slopes of the Rockies. 4. Mistral - Blows from the Alps over France towards the Mediterranean Sea. It is channelled through the

Rhone valley. It is very cold and dry with a high speed. 5. Sirocco - Sirocco is a Mediterranean wind that comes from the Sahara. The Sirocco causes dusty dry

conditions along the northern coast of Africa, storms in the Mediterranean Sea, and cool, wet weather inEurope. (Blood rain in Italy)

6. Khamsin - is an oppressive, hot, dry and dusty south or south-east wind occurring in North Africa 7. Harmattan wind - Dry, dusty and north-easterly winds which occur in west Africa north of the equator.

Also known as the 'doctor'because of its invigorating dryness compared with humid tropical air. (Fall ntemperature) [End of November middle of March]

8. Fremantle wind - In Western Australia, Fremantle wind brings relief from summer high temperatures.(Freco doctor)

9. Sarmun is the local wind of Kurdistan region, Santa Ana is the local wind of California and Zonda is thelocal wind of Argentina.

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11.

Drainage Pattern

1. Concordant drainage - Correlates to the topology and geology of the area. 2. Consequent Rivers - follow the general direction of the slope [Godavari, Krishna and Cauvery] 3. Subsequent Rivers - A tributary stream that is formed by headward erosion along an underlying rock after

the main drainage pattern (consequent river) has been established [ Chambal, Sind, Ken, Betwa, Tons andSon]

4. Obsequent Rivers - After the valley development of consequent and subsequent rivers, obsequent riversmay form at right angles to the subsequent rivers and flow opposite to the direction of flow of the originalconsequent river

5. Resequent Rivers - Flows in the same direction as that of the initial consequent drainage. [originate at amuch later stage]

6. Discordant or Insequent drainage patterns - does not correlate to the topology (surface relief features)and geology of the area. [ two main types: antecedent and superimposed]

7. Antecedent Drainage or Inconsequent Drainage - A part of a river slope and the surrounding area getsuplifted, and the river sticks to its original slope, cutting through the uplifted portion like a saw (verticalerosion) and forming deep gorges. The soil formed is weak (mostly weak sediments), and the rivers easilyerode it. [Example: Indus, Sutlej, Brahmaputra and other Himalayan rivers that are older than theHimalayas themselves.]

8. Superimposed or Epigenetic (Discordant) or Superinduced Drainage - When a river flowing over asofter rock stratum reaches the harder basal rocks but continues to follow the initial slope, it seems to haveno relation with the harder rock bed. : The rivers have high erosive power so that they can cut through theunderlying strata. [The Damodar, the Subarnarekha, the Chambal, the Banas and the rivers flowing at theRewa Plateau]

9. Radial Drainage - The Narmada, Son and Mahanadi originate from Amarkantak Hills and flow in differentdirections.