Unit Ivstratigraphy 141015075230 Conversion Gate01(1)

StratigraphyStratigraphy

Unit-IVUnit-IV


• Principle of stratigraphy and co-relation, geologicaltime scale, physiographic divisions of India – study offormations occurring in peninsular India.

• Principle of stratigraphy and co-relation, geologicaltime scale, physiographic divisions of India – study offormations occurring in peninsular India.



• Stratigraphy is the chronological study of sedimentaryrocks. Among the different group of rocks. Onlysedimentary rock are amenable to such study because ofthe principle of the order of superposition.

Stratigraphy• (Strata= a set of sedimentary beds, graphy= description)

reveals various details of the history of the earth duringthe different periods of geological past, from thebeginning till the present.

• Through stratigraphy we can know the past details ofclimate, geography, glaciations, orogeny, eperogeny,evolution and migration of plants and animals.

• Thus as this branch of geology reveals the history of ourplanet, it is called as “Historical Geology”.

• Stratigraphy is the chronological study of sedimentaryrocks. Among the different group of rocks. Onlysedimentary rock are amenable to such study because ofthe principle of the order of superposition.

Stratigraphy• (Strata= a set of sedimentary beds, graphy= description)

reveals various details of the history of the earth duringthe different periods of geological past, from thebeginning till the present.

• Through stratigraphy we can know the past details ofclimate, geography, glaciations, orogeny, eperogeny,evolution and migration of plants and animals.

• Thus as this branch of geology reveals the history of ourplanet, it is called as “Historical Geology”.


Aims of StratigraphyAims of Stratigraphy

The aim of stratigraphy are• (i) To study the chronological sequence of

scattered strata of different places• (ii) To correlate them with that of the worldwide or

established regional chronological framework.• (iii) To interpret the geological history of the earth

as a whole from the forgoing data.• Such a study paves the way for the arrangement of

the sedimentary rock in the chronologicalsequence in which they were laid on the surface ofearth.

The aim of stratigraphy are• (i) To study the chronological sequence of

scattered strata of different places• (ii) To correlate them with that of the worldwide or

established regional chronological framework.• (iii) To interpret the geological history of the earth

as a whole from the forgoing data.• Such a study paves the way for the arrangement of

the sedimentary rock in the chronologicalsequence in which they were laid on the surface ofearth.

Chronological sequence of scatteredStrata

Chronological sequence of scatteredStrata

Principle of StratigraphyPrinciple of Stratigraphy

• The aims of stratigraphy are achieved mainly in threedifferent ways which are named as principles ofstratigraphy. They are lithology, order of superpositionand fossil content. All these three naturalphenomenon becomes effective means because of thelogical fact that the “Present is the key to the past”.

• The aims of stratigraphy are achieved mainly in threedifferent ways which are named as principles ofstratigraphy. They are lithology, order of superpositionand fossil content. All these three naturalphenomenon becomes effective means because of thelogical fact that the “Present is the key to the past”.

“Present is the key to the past”“Present is the key to the past”

Principle of StratigraphyPrinciple of StratigraphyPresent is the Key to the PastThis may be briefly explained as follows:• By careful study it is possible to link a particular

geological period with the lithology, order ofsuperposition and fossil content concerned. From thepresent day observation, we know that the different typesof rocks with distinctive minerals and composition areformed under different environment (such as dry,humid, glacial, marine, fluvial, lacustine and terrestrial).

• This means in the past too, depending on differentenvironmental conditions that had prevailed duringdifferent geological periods, different types of rocks havebeen formed. This fact helps in correlation and also inrevealing the part history of the earth.

Present is the Key to the PastThis may be briefly explained as follows:• By careful study it is possible to link a particular

geological period with the lithology, order ofsuperposition and fossil content concerned. From thepresent day observation, we know that the different typesof rocks with distinctive minerals and composition areformed under different environment (such as dry,humid, glacial, marine, fluvial, lacustine and terrestrial).

• This means in the past too, depending on differentenvironmental conditions that had prevailed duringdifferent geological periods, different types of rocks havebeen formed. This fact helps in correlation and also inrevealing the part history of the earth.

“Present is the Key to the Past”“Present is the Key to the Past”

Principle of StratigraphyPrinciple of Stratigraphy• Thus the occurrence of feldspar-rich arkose type

sandstone or boulder beds reveal intense coldclimate conditions that had prevailed during theirformation.• Further, their peculiarities make it easy to

correlate them with the rocks of similar kind inother places. All of them might have been formedduring the same geological period.• Of course, since glacial periods had occurred again

and again in the geological past, to make propercorrelation, other aspects, i.e. order ofsuperposition, fossil content etc. also have to betaken into consideration.

• Thus the occurrence of feldspar-rich arkose typesandstone or boulder beds reveal intense coldclimate conditions that had prevailed during theirformation.• Further, their peculiarities make it easy to

correlate them with the rocks of similar kind inother places. All of them might have been formedduring the same geological period.• Of course, since glacial periods had occurred again

and again in the geological past, to make propercorrelation, other aspects, i.e. order ofsuperposition, fossil content etc. also have to betaken into consideration.

Principle of StratigraphyPrinciple of StratigraphyLithology (litho= rock, logo= study)• The term lithology is synonymous to petrology. But the

term petrology is widely used, whereas the term lithologyis used in general only in stratigraphy.

• This refers to the study of chemical and mineralcomposition of rocks. The fact that “ rocks of a similarkind with similar chemical and mineral composition areformed at a given time in different places” is veryimportant and useful in correlation. Sometimes, specialstress is laid on heavy mineral studies.

• Lithology also reveal some environmental aspects of thesequence and types of rocks.

Lithology (litho= rock, logo= study)• The term lithology is synonymous to petrology. But the

term petrology is widely used, whereas the term lithologyis used in general only in stratigraphy.

• This refers to the study of chemical and mineralcomposition of rocks. The fact that “ rocks of a similarkind with similar chemical and mineral composition areformed at a given time in different places” is veryimportant and useful in correlation. Sometimes, specialstress is laid on heavy mineral studies.

• Lithology also reveal some environmental aspects of thesequence and types of rocks.

Lithology (Litho= rock, Logo= study)Lithology (Litho= rock, Logo= study)

Principle of StratigraphyPrinciple of StratigraphyOrder of Superposition• The chronological importance of the order of

superposition in sedimentary rocks was firstrecognized by N.Steno in 1669. According to thisprinciple, in a set of strata successively youngerbeds lie upwards.• This is natural because when sedimentation takes

place, it commences from the bottom of the basin.Therefore, the bottommost layer is the first to beformed and hence the oldest of the set. Over thislayer lies the next formed one and above it lie stillyounger beds. Thus successively younger bedsoccur upward in an undisturbed sequence of beds.

Order of Superposition• The chronological importance of the order of

superposition in sedimentary rocks was firstrecognized by N.Steno in 1669. According to thisprinciple, in a set of strata successively youngerbeds lie upwards.• This is natural because when sedimentation takes

place, it commences from the bottom of the basin.Therefore, the bottommost layer is the first to beformed and hence the oldest of the set. Over thislayer lies the next formed one and above it lie stillyounger beds. Thus successively younger bedsoccur upward in an undisturbed sequence of beds.

Order of SuperpositionOrder of Superposition


• Of course, when the beds are overturned, theorder of superposition appear in reverse. However,by verifying the actual top and bottom of beds, it ispossible to know the proper order ofsuperposition.• An important fact of the order of superposition is

that similar sequence of rocks are expected todevelop in different places during the samegeological period, under similar conditions.• Based on this fact, correlation of different scattered

of rocks can be made.

• Of course, when the beds are overturned, theorder of superposition appear in reverse. However,by verifying the actual top and bottom of beds, it ispossible to know the proper order ofsuperposition.• An important fact of the order of superposition is

that similar sequence of rocks are expected todevelop in different places during the samegeological period, under similar conditions.• Based on this fact, correlation of different scattered

of rocks can be made.


• Fossils may be defined as “ the relicts andremnants of ancient animals and plants that havebeen preserved inside the rocks by naturalprocess”• Occurrence of fossils in sedimentary rocks is a

matter of chance because under very favorableconditions they occur.• This means all sedimentary rocks do not possess

fossil fuels. But if they are present they very usefulgive valuable information.

• Fossils may be defined as “ the relicts andremnants of ancient animals and plants that havebeen preserved inside the rocks by naturalprocess”• Occurrence of fossils in sedimentary rocks is a

matter of chance because under very favorableconditions they occur.• This means all sedimentary rocks do not possess

fossil fuels. But if they are present they very usefulgive valuable information.

FossilsFossils


• The fossil and the rocks which possess thembelong to the same age group, i.e. the rocks hadformed in a particular geological period will behaving the restrict of only of animals and plantswhich were existing over the time.• We find today the different plants and animals

flourish different. If we keep in mind that the• “present is the key to the past”. With the help

of fossil we can understand the history of earth.

• The fossil and the rocks which possess thembelong to the same age group, i.e. the rocks hadformed in a particular geological period will behaving the restrict of only of animals and plantswhich were existing over the time.• We find today the different plants and animals

flourish different. If we keep in mind that the• “present is the key to the past”. With the help

of fossil we can understand the history of earth.

What is the Earth’s time scale?What is the Earth’s time scale?

• The Geological time scale is a record of the lifeforms and geological events in Earth’s history.

• Scientists developed the time scale by studyingrock layers and fossils world wide.

• Radioactive dating helped determine theabsolute divisions in the time scale.

• The Geological time scale is a record of the lifeforms and geological events in Earth’s history.

• Scientists developed the time scale by studyingrock layers and fossils world wide.

• Radioactive dating helped determine theabsolute divisions in the time scale.

Geological Time ScaleGeological Time Scale• It is believed that the earth came into existence nearly

4500 million years ago. Therefore, its history isspreading over all this lengthy period.

• For the sake of convenience of study and references andalso for relative comparison of ages of different sequenceof rocks found in different places on the earth’s surface,it is necessary to have a proper framework of geologicaltime.

• This need is fulfilled by the “Geological Time Scale”,which is internationally accepted. It is like the calendarof an year. As an year is divided into different months,each month into weeks, each week into days, each dayinto hours. and so on the geological time scale is alsosimilarly subdivided into smaller and smaller unit to suitthe stratigraphical study and correlation.

• It is believed that the earth came into existence nearly4500 million years ago. Therefore, its history isspreading over all this lengthy period.

• For the sake of convenience of study and references andalso for relative comparison of ages of different sequenceof rocks found in different places on the earth’s surface,it is necessary to have a proper framework of geologicaltime.

• This need is fulfilled by the “Geological Time Scale”,which is internationally accepted. It is like the calendarof an year. As an year is divided into different months,each month into weeks, each week into days, each dayinto hours. and so on the geological time scale is alsosimilarly subdivided into smaller and smaller unit to suitthe stratigraphical study and correlation.

Geological Time ScaleGeological Time Scale

Geological Time ScaleGeological Time Scale• The geological time scale is subdivided into number of

eras. Each era comprises a number of “periods”,which, in turn are subdivided into “epochs”. Anumber of “ages” make up an epoch. These sub unitsof an age are sometimes called “hemeras” or “Phases”.

• The similarity of the mode of subdivision of a year andgeological time scale is up to this extent only.

• The geological time scale is subdivided into number oferas. Each era comprises a number of “periods”,which, in turn are subdivided into “epochs”. Anumber of “ages” make up an epoch. These sub unitsof an age are sometimes called “hemeras” or “Phases”.

• The similarity of the mode of subdivision of a year andgeological time scale is up to this extent only.

Geological Time ScaleGeological Time Scale• The duration or time interval between any two such

successive extraordinary events is described as an era.Thus, based on this principle, the geological timescale, which represents the entire period of the earth’shistory, has been subdivided into six eras. They are:Achaean Era (The Oldest), Precambrian era, Primaryera, Secondary era, Tertiary era and Quaternary era(The last and the youngest).

• The duration or time interval between any two suchsuccessive extraordinary events is described as an era.Thus, based on this principle, the geological timescale, which represents the entire period of the earth’shistory, has been subdivided into six eras. They are:Achaean Era (The Oldest), Precambrian era, Primaryera, Secondary era, Tertiary era and Quaternary era(The last and the youngest).

Geological Time ScaleGeological Time ScaleThey are as follows:They are as follows:Geological Time Scale

1 Achaean Era Azoic Era (Zoe= life, Azoic= lifeless, means an era withoutlife)

2 Precambrian Era Proterozoic Era (Protero= Very early, meaning an era with veryearly life, which is not recorded as fossils)

3 Primary Era Palaeozoic Era (Palaeo= ancient or old, meaning the era with firstimportant life which is recorded as fossils).

4 Secondary Era Mesozoic Era (Mesos= middle, meaning an era with life, whichis not old or not recent.

5 Tertiary Era Cenozoic Era (Ceno or Kaino= recent, meaning an era withrecent life)

6 Quaternary Era Psychozoic Era (Psycho= reasoning pr thinking, meaning an erawith life which has reasoning or thinking capacity.

Geological Time ScaleGeological Time ScaleGeological Time ScaleGeological Time Scale



Divisions of Geologic TimeDivisions of Geologic Time

• Eras are subdivided into periods...periods aresubdivided into epochs.• Eras are subdivided into periods...periods are

subdivided into epochs.EraEra

PeriodPeriod

Epoch

E + P = EPE + P = EP

Divisions of Geologic TimeDivisions of Geologic Time

• Geological time begins with Precambrian Time.Precambrian time covers approximately 88% ofEarth’s history.

• Geological time begins with Precambrian Time.Precambrian time covers approximately 88% ofEarth’s history.

FOUR Eras…FOUR Eras…

• PRE-CAMBRIAN – 88% of earth’s history

• Paleozoic (ancient life)– 544 million years ago…lasted 300 million yrs

• Mesozoic (middle life)– 245 million years ago…lasted 180 million yrs

• Cenozoic (recent life)– 65 million years ago…continues through present day

• PRE-CAMBRIAN – 88% of earth’s history

• Paleozoic (ancient life)– 544 million years ago…lasted 300 million yrs

• Mesozoic (middle life)– 245 million years ago…lasted 180 million yrs

• Cenozoic (recent life)– 65 million years ago…continues through present day

Today…Today…• Today we are in the Holocene Epoch of the

Quaternary Period of the Cenozoic Era.• Today we are in the Holocene Epoch of the

Quaternary Period of the Cenozoic Era.

Which unit is the largest?

Which unit is the smallest?

Which unit is the largest?

Which unit is the smallest?

Today…Today…• Today we are in the Holocene Epoch of the

Quaternary Period of the Cenozoic Era.• Today we are in the Holocene Epoch of the

Quaternary Period of the Cenozoic Era.

Paleozoic Era (Ancient Life)Paleozoic Era (Ancient Life)• The Cambrian period is the 1st period of the Paleozoic Era.

“Age of the Trilobites”• Explosion of life in the oceans began during this era.• Most of the continents were covered in warm, shallow

seas.– Invertebrates were dominate - Trilobites– Fish emerged during this time– Fish led to the arrival of amphibians• The end of the Paleozoic era is called the “Age of Amphibians”

– Early land plants including mosses, ferns and cone-bearingplants.– The early coal forming forests were also formed during this time.

• The Cambrian period is the 1st period of the Paleozoic Era.“Age of the Trilobites”• Explosion of life in the oceans began during this era.• Most of the continents were covered in warm, shallow

seas.– Invertebrates were dominate - Trilobites– Fish emerged during this time– Fish led to the arrival of amphibians• The end of the Paleozoic era is called the “Age of Amphibians”

– Early land plants including mosses, ferns and cone-bearingplants.– The early coal forming forests were also formed during this time.

Paleozoic EraPaleozoic Era• Much of the limestone quarried for building and

industrial purposes, as well as the coal deposits ofwestern Europe and the eastern United States, wereformed during the Paleozoic.

• The Cambrian (beginning) opened with the breakupof the world-continent Rodina and closed with theformation of Pangaea, as the Earth's continents cametogether once again.– This event is thought to have caused the climate

changes that led to mass extinction event.• The Appalachian mountains were formed during

this time.

• Much of the limestone quarried for building andindustrial purposes, as well as the coal deposits ofwestern Europe and the eastern United States, wereformed during the Paleozoic.

• The Cambrian (beginning) opened with the breakupof the world-continent Rodina and closed with theformation of Pangaea, as the Earth's continents cametogether once again.– This event is thought to have caused the climate

changes that led to mass extinction event.• The Appalachian mountains were formed during

this time.

Paleozoic EraPaleozoic Era• At the end of the Paleozoic, the largest massextinction in history wiped out approximately 90%of all marine animal species and 70% of landanimals.– Possible causes of this Mass Extinction Event• Lowering of sea levels when the continents were

rejoined as Pangaea (convergent boundary)• Increased volcanic activity (ash and dust)• Climate changes – cooler climate

• At the end of the Paleozoic, the largest massextinction in history wiped out approximately 90%of all marine animal species and 70% of landanimals.– Possible causes of this Mass Extinction Event• Lowering of sea levels when the continents were

rejoined as Pangaea (convergent boundary)• Increased volcanic activity (ash and dust)• Climate changes – cooler climate

TrilobitesTrilobites

• Lived in Earth’s ancient seas• Extinct before the dinosaurs came

into existence• Cambrian Period is know as the

“Age of the Trilobites” (put in ontable)

• Lived in Earth’s ancient seas• Extinct before the dinosaurs came

into existence• Cambrian Period is know as the

“Age of the Trilobites” (put in ontable)

BrachiopodsBrachiopods

• Marine animals that resemble clams.• Marine animals that resemble clams.

Early FishEarly Fish

Early fish did not have jaws.Some species of sharks werein existence at this time.

Frilled Shark that was found in Japan in January 2007. This shark was considereda “living fossil”Frilled Shark that was found in Japan in January 2007. This shark was considereda “living fossil”

Early Land PlantsEarly Land Plants

Cone bearing plants

FernsFerns

Mosses

Mesozoic Era – Middle LifeMesozoic Era – Middle Life• At the beginning of this era the continents

were joined as Pangaea.• Pangaea broke up around the middle of this

era.• Reptiles became the most abundant animals

because of their ability to adapt to the drierclimate of the Mesozoic Era.– Skin maintains body fluids– Embryos live in shells

• At the beginning of this era the continentswere joined as Pangaea.• Pangaea broke up around the middle of this

era.• Reptiles became the most abundant animals

because of their ability to adapt to the drierclimate of the Mesozoic Era.– Skin maintains body fluids– Embryos live in shells

Mesozoic EraMesozoic Era• Dinosaurs were also very active in this era.– First small dinosaurs appeared in the Triassic

Period.– Larger and more abundant dinosaurs appeared in

the Jurassic Period.• Small mammals and birds also appeared

during this era.– The mammals were small, warm-blooded

animals. Hair covering their bodies.• These characteristics help them survive in changing

environments.

• Dinosaurs were also very active in this era.– First small dinosaurs appeared in the Triassic

Period.– Larger and more abundant dinosaurs appeared in

the Jurassic Period.• Small mammals and birds also appeared

during this era.– The mammals were small, warm-blooded

animals. Hair covering their bodies.• These characteristics help them survive in changing

environments.

Mesozoic EraMesozoic Era• The main plant life of this time were

Gymnosperms or plants that produce seeds, butno flowers.– Pine Trees

• Flowering plants appeared during the END of thisera.

• The main plant life of this time wereGymnosperms or plants that produce seeds, butno flowers.– Pine Trees

• Flowering plants appeared during the END of thisera.

Mesozoic EraMesozoic Era• This era ended with a mass extinction event about

65 million years ago.–Many groups of animals, including the dinosaurs

disappeared suddenly at this time.

• Many scientists believe that this event was causedby a comet or asteroid colliding with the Earth.

• This era ended with a mass extinction event about65 million years ago.–Many groups of animals, including the dinosaurs

disappeared suddenly at this time.

• Many scientists believe that this event was causedby a comet or asteroid colliding with the Earth.

Mesozoic Era – Mass Extinction EventMesozoic Era – Mass Extinction Event• Asteroid or Comet collides with Earth.

– Huge cloud of smoke and dust fills the air– Blocks out sunlight– Plants die– Animals that eat plants die– Animals that eat plant-eaters die.

• However, not all forms of life died during this event.Many animals that you see today are descendantsfrom the survivors of this extinction event.

• Asteroid or Comet collides with Earth.

– Huge cloud of smoke and dust fills the air– Blocks out sunlight– Plants die– Animals that eat plants die– Animals that eat plant-eaters die.

• However, not all forms of life died during this event.Many animals that you see today are descendantsfrom the survivors of this extinction event.

DinosaursDinosaurs

Mesozoic ReptilesMesozoic Reptiles

Mesozoic MammalsMesozoic Mammals

Mesozoic PlantsMesozoic Plants

Flowering plants evolvedtowards the end of theMesozoic Era.

Flowering plants evolvedtowards the end of theMesozoic Era.

Cenozoic Era – Recent LifeCenozoic Era – Recent Life• Began about 65 million years ago and continues today!!!!!– Climate was warm and mild.– Marine animals such as whales and dolphins evolved.

• Mammals began to increase and evolve adaptations thatallowed them to live in many different environments –land, air and the sea.– Grasses increased and provided a food source for grazing animals

• Many mountain ranges formed during the Cenozoic Era– Alps in Europe and Himalayas in India; Rocky Mountains in the

USA

• Began about 65 million years ago and continues today!!!!!– Climate was warm and mild.– Marine animals such as whales and dolphins evolved.

• Mammals began to increase and evolve adaptations thatallowed them to live in many different environments –land, air and the sea.– Grasses increased and provided a food source for grazing animals

• Many mountain ranges formed during the Cenozoic Era– Alps in Europe and Himalayas in India; Rocky Mountains in the

USA

Cenozoic EraCenozoic Era• Growth of these mountains may have helped to cool

down the climate– Ice Ages occurred late in the Cenozoic Era (Quaternary

Period).

• As the climate changed, the animals had to adapt tothe rise and fall of the oceans caused by meltingglaciers.

• This era is sometimes called the “Age of Mammals”

• Growth of these mountains may have helped to cooldown the climate– Ice Ages occurred late in the Cenozoic Era (Quaternary

Period).

• As the climate changed, the animals had to adapt tothe rise and fall of the oceans caused by meltingglaciers.

• This era is sometimes called the “Age of Mammals”

Cenozoic EraCenozoic Era• Marine animal examples:– Algae, Mollusks, Fish and Mammals

• Land animal examples:– Bats, Cats, Dogs, Cattle and Humans– Humans are thought to have appeared around 3.5 million

years ago (during the most recent period – Quaternary).

• Flowering plants were now the most common plantlife.

• Marine animal examples:– Algae, Mollusks, Fish and Mammals

• Land animal examples:– Bats, Cats, Dogs, Cattle and Humans– Humans are thought to have appeared around 3.5 million

years ago (during the most recent period – Quaternary).

• Flowering plants were now the most common plantlife.

Cenozoic MammalsCenozoic Mammals

Flowering Plants were common during theCenozoic Era

Flowering Plants were common during theCenozoic Era

Geological Divisions of IndiaGeological Divisions of India

• The Physiographical map shows clearly thatIndia is divisible into three parts, each havingdistinguish character of its own. These threeparts are

• Extra-pennsula,

• Indo-Gangetic alluvial plains and

• Peninsula.

• The Physiographical map shows clearly thatIndia is divisible into three parts, each havingdistinguish character of its own. These threeparts are

• Extra-pennsula,

• Indo-Gangetic alluvial plains and

• Peninsula.

Extra-PeninsulaExtra-Peninsula


• The extra –peninsular part is the mountainousregion of the giant Himalayan ranges. TheIndo-Gangetic plains are the vast plain landsstretching across northern India from Assamand Bengal in the east, through Bihar and UttarPradesh to Punjab and Sind in the vest.

• The extra –peninsular part is the mountainousregion of the giant Himalayan ranges. TheIndo-Gangetic plains are the vast plain landsstretching across northern India from Assamand Bengal in the east, through Bihar and UttarPradesh to Punjab and Sind in the vest.

Indo-Gangetic alluvial plainsIndo-Gangetic alluvial plains

Peninsula.Peninsula.

Peninsula.Peninsula.

• The peninsular part lies to the south of theIndo-Gangetic plains.

• The clear difference that we notice among thesethree parts of our country from the geologicalpoint of view can be appreciated well in termsof topography (i.e. Physiography), stratigraphyand structural division.

• The peninsular part lies to the south of theIndo-Gangetic plains.

• The clear difference that we notice among thesethree parts of our country from the geologicalpoint of view can be appreciated well in termsof topography (i.e. Physiography), stratigraphyand structural division.

Geological Divisions of IndiaGeological Divisions of IndiaPhysiographical Divisions

• Based on surface, i.e. physiography, the threefolddivisions of India can be well appreciated as follows:• The peninsula is an ancient plateau which has been

exposed for long ages to denudation andapproaching peneplain. Its mountain ranges are ofthe relict type, i.e. they represent the survival of hardmass of rock which have withstood weathering anderosion. Its rivers move, for the most part, over a flatcountry with low and have built up shallow and broadvalleys.

Physiographical Divisions

• Based on surface, i.e. physiography, the threefolddivisions of India can be well appreciated as follows:• The peninsula is an ancient plateau which has been

exposed for long ages to denudation andapproaching peneplain. Its mountain ranges are ofthe relict type, i.e. they represent the survival of hardmass of rock which have withstood weathering anderosion. Its rivers move, for the most part, over a flatcountry with low and have built up shallow and broadvalleys.



• The extra-peninsula, on the other hand, is a highlyirregular region of folded and over-thrust mountainchains of geologically recent origin. Its rivers areyouthful and are actively eroding and over-thrustmountain chains of geologically recent origin.

• Its rivers are youthful and are actively eroding theirbeds along their courses and carving out deep andsteep sided georges.

• The extra-peninsula, on the other hand, is a highlyirregular region of folded and over-thrust mountainchains of geologically recent origin. Its rivers areyouthful and are actively eroding and over-thrustmountain chains of geologically recent origin.

• Its rivers are youthful and are actively eroding theirbeds along their courses and carving out deep andsteep sided georges.



• The Indo-Gangetic plains are broad,monotonous, plain expanses. These are built ofrecent alluvium through which the river flowsluggishly towards the seas their respectivedestination.

• The Indo-Gangetic plains are broad,monotonous, plain expanses. These are built ofrecent alluvium through which the river flowsluggishly towards the seas their respectivedestination.

Indo-Gangetic alluvial plainsIndo-Gangetic alluvial plains

Physiographical DivisionsPhysiographical Divisions

ReferencesReferences

• Engineering and General Geology :By ParbinSingh• Textbook of Engineering Geology :N.Chenna

Kesavullu

• Engineering and General Geology :By ParbinSingh• Textbook of Engineering Geology :N.Chenna

Kesavullu

Thanks !Thanks !

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Unit Ivstratigraphy 141015075230 Conversion Gate01(1)