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Indian Geography > Geological structure > Flashcards

Geological structure Flashcards

1
Q

geological division of regions in India?

A

1) triple Tectonic division
1. 1) Peninsular region incl meghalaya plateau and Kutcch-kathiawar: one of oldest lm, dominated by open senile topography; not undergone marine submergence since Cambrian period; not much affected by tectonic forces
1. 2) extra-peninsular region: Himalayas and their eastern extension incl A&N: most youthful reliefs of earth; origin in tethys sea;prone to tectonic forces
1. 3) Indo-gangetic plain: flat, featureless and monotonous
2) Others recognise only two divisons 1.1 and 1.2-1.3together

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2
Q

Geological history of India: 4 major divisions: Intro?

A
  • > represents a ‘monumental assemblage of rocks of different character belonging to different ages, ranging frm pre-Cambrian to recent times’
  • > Sir T. Holland of GSI: 4 rock systems
    1) Archaean (2)Purana (3)Dravidian (4) Aryan
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3
Q

Archaean Rock system: intro?

A
  • > J.D. Dana: used ‘archaean’ for rock str prior to Cambrian system
  • > oldest in world
  • > includes two groups: (1)Archaean system-Gneisses and schists, which are the oldest metamorphosed igneous rocks in india (2) Dharwar system, which are the oldest metamorphosed sedimentary rocks of India
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4
Q

Archaean system-Gneisses and schists: age?

A

1) Age: oldest; formed at the time of cooling and solidification of upper crust of earth’s surface in pre-cambrian era (4Bn ya)
2) Origin: details of their origin under speculation
3) characteristics: azoic; thoroughly crystalline; extremely contorted and faulted; well defined foliated str; often formed as plutonic intrusions; often lie under strata formed subsequently and thus form core of continents; aka ‘Funadamental complex’or ‘Basement complex’
4) rocks: can be igneous or metamorphosed; 2/3rd Penin India is covered by gneiss; mineral composition may vary leading to granite as well as gabro; foliated or banded str; mostly crystalline like mica, talc, hornblende, chlorite
5) Location: central and southern parts of Penin (KN plateau); to the NE, in Odisha, Meghalaya, MP, Chhatisgarh (Bastar) and chhotanagpur plateau of JH; in isolated outcrops frm along aravallis; also exposed all along Himalayas, forming bulk of high ranges and backbone of the mt system

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5
Q

Archaean system-Gneisses and schists: origin?

A

details of their origin under speculation

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6
Q

Archaean system-Gneisses and schists: characteristics?

A
  • > azoic;
  • > thoroughly crystalline;
  • > extremely contorted and faulted;
  • > well defined foliated str(though usually igneous rocks do not have layered str);
  • > often formed as plutonic intrusions;
  • > often lie under strata formed subsequently and thus form core of continents; aka ‘Funadamental complex’or ‘Basement complex’
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7
Q

Archaean system-Gneisses and schists: rocks

A

can be igneous or metamorphosed; 2/3rd Penin India is covered by gneiss; mineral composition may vary leading to granite as well as gabro; foliated or banded str; mostly crystalline like mica, talc, hornblende, chlorite

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8
Q

Archaean system-Gneisses and schists: location?

A

central and southern parts of Penin (KN plateau); to the NE, in Odisha, Meghalaya, MP, Chhatisgarh (Bastar) and chhotanagpur plateau of JH; in isolated outcrops frm along aravallis; also exposed all along Himalayas, forming bulk of high ranges and backbone of the mt system

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9
Q

Dharwar system?

A

1) Age: Acc to Wadia, its the most ancient metamorphosed sedimentary rock system of India, as old as, if not older than the basement gneiss and schists
2) Origin: weathering of earliest Archaean gneiss and schists yielded the sediments which were deposited on the sea bed, which formed the oldest sedimentary strata, known as dharwar system
3) characteristics: mostly enriched in manganese and iron ore; The Champions series containing gold mines lie within this system. This Champion system is named after the Champion reef in the Kolar Gold Fields.
4) rocks: incl highly metamorphosed(so much so that they are indistinguishable frm their primitive formations) rocks of both sedimentary and igneous nature; major rocks incl Hornblende, quartzites, phyllites, slates, limestones nd dolomites
5) Location: very well developed in the Dharwar-Bellary-Mysore belt of KN (hence the name); also in JH(Ranchi, Hazaribagh), MP(balaghat and Rewa), Chhatisgarh (Bastar, Dantewada), odisha keonjhar and sundergarh) and in aravalis betn Jaipur and palanpur. also well represented in HImalayas, in central, nrthern zones and meghalaya plateau.
6) Significance: economically most imp; possess high grade iron ore, Mn, Cu, Pb, Au, quartzites, slate, mica etc.

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10
Q

Dharwar system: age?

A

Acc to Wadia, its the most ancient metamorphosed sedimentary rock system of India, as old as, if not older than the basement gneiss and schists

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11
Q

Dharwar system: origin?

A

weathering of earliest Archaean gneiss and schists yielded the sediments which were deposited on the sea bed, which formed the oldest sedimentary strata, known as dharwar system

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12
Q

Dharwar system: characteristics?

A

mostly enriched in manganese and iron ore; The Champions series containing gold mines lie within this system. This Champion system is named after the Champion reef in the Kolar Gold Fields.

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13
Q

Dharwar system: rocks?

A

incl highly metamorphosed(so much so that they are indistinguishable frm their primitive formations) rocks of both sedimentary and igneous nature; major rocks incl Hornblende, quartzites, phyllites, slates, limestones nd dolomites

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14
Q

Dharwar system: location?

A

very well developed in the Dharwar-Bellary-Mysore belt of KN (hence the name); also in JH(Ranchi, Hazaribagh), MP(balaghat and Rewa), Chhatisgarh (Bastar, Dantewada), odisha keonjhar and sundergarh) and in aravalis betn Jaipur and palanpur. also well represented in HImalayas, in central, nrthern zones and meghalaya plateau.

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15
Q

Dharwar system: significance?

A

economically most imp; possess high grade iron ore, Mn, Cu, Pb, Au, quartzites, slate, mica etc.

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16
Q

Purana Rock system: intro?

A
  • > 1400-600mya (Proterozoic times)
  • > word used in India in place of Proterozoic
  • > includes 2 divisions: Cuddapah and VIndhyan system
  • > Purana and Archaean rock systems are separated by Eparchean discontinuity
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17
Q

Cuddapah system?

A

1) Age: 1400mya-1300mya
2) origin: deposition of unfossiliferous clay, slates, quartzites, sandstones and limestones in great synclinal basins
3) characteristics: -
4) rocks: steatite, quartzite, limestone, jasper, cherts
5) location:
a) Kurnool district of andhraP: outcrop is irregular crescent shape, concave towards coast suggesting that the rocks were subjected compressive forces directed frm concave side near which stood the high mts that supplied the sediments
(b) Southern Chhatisgarh: Dantewara, bastar, Kanker, Raipur, Durg
(c) some in Singhbhum of JH; Kalahandi of Odisha
(d) along main axis of aravallis frm delhi to Idar in GJ
(e) some in KN too
6) significance:
(a) ores of Fe,Mn, Cu, Co, Ni, asbestos, jasper etc.
(b) building purpose quartzites and cement grade limestones

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18
Q

Cuddapah system: age?

A

1400my-1300my

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19
Q

Cuddapah system: origin?

A

deposition of unfossiliferous clay, slates, quartzites, sandstones and limestones in great synclinal basins

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20
Q

Cuddapah system: rocks?

A

steatite, quartzite, limestone, jasper, cherts

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21
Q

Cuddapah system: location?

A

a) Kurnool district of andhraP: outcrop is irregular crescent shape, concave towards coast suggesting that the rocks were subjected compressive forces directed frm concave side near which stood the high mts that supplied the sediments
(b) Southern Chhatisgarh: Dantewara, bastar, Kanker, Raipur, Durg
(c) some in Singhbhum of JH; Kalahandi of Odisha
(d) along main axis of aravallis frm delhi to Idar in GJ
(e) some in KN too

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22
Q

Cuddapah system: significance?

A

(a) ores of Fe,Mn, Cu, Co, Ni, asbestos, jasper etc.

(b) building purpose quartzites and cement grade limestones

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23
Q

Vindhyan system?

A

1) age: Lower Vindhyan (1300-1100my) and upper Vindhyan (1000-600my)
2) origin:
2. 1) Lower Vindhyan: marine in origin.
2. 2) upper Vindhyan: fluvialtile
3) characteristics: ancient sedimentary rocks super-imposed on Archaean base; stratified formation of limestones, shales and sandstones, often over 4000m thick; general lack of recognisable fossils; the two stratas are separated by an unconformity, which is quite prominent in the north but disappears in southern areas;devoid of metalliferous minerals of Mewar, chittaurgarh etc,
3. 1) Lower Vindhyas: calacareous in nature; tectonic deformation by folding
3. 2) Upper Vindhyas: gently lying in undisturbed horizontal strata
4) rocks: limestones, shales and sandstones
5) location:
(a) Sasaram and Rohtas in western Bihar to Chittaurgarh in Raj with a GAP in Bundelkhand. Large area of this belt is covered by deccan trap.
(b) also in Chhatisgarh, Bhima valley in KN; Kurnool of andhraP
(c) continue to the north under Gangetic alluvium and perhaps even under HImalayas
(d) Lower vindhyan : in Son valley; in chhatisgarh; in Bhima valley; Mewar
(e) Upper: KN
6) Significance:
(a) upper Vindhyas: two diamond bearing horizons-panna and golconda diamond mines
(b) large qty of excellent and durable stones, flagstones, ornamental stones, glass making sand and some coal.

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24
Q

Vindhyan system: age?

A

Lower Vindhyan (1300-1100my) and upper Vindhyan (1000-600my)

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25
Q

Vindhyan system: origin?

A
  1. 1) Lower Vindhyan: marine in origin.

2. 2) upper Vindhyan: fluvialtile

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26
Q

Vindhyan system: characteristics?

A

ancient sedimentary rocks super-imposed on Archaean base; stratified formation of limestones, shales and sandstones, often over 4000m thick; general lack of recognisable fossils; the two stratas are separated by an unconformity, which is quite prominent in the north but disappears in southern areas;devoid of metalliferous minerals of Mewar, chittaurgarh etc,

  1. 1) Lower Vindhyas: calacareous in nature; tectonic deformation by folding
  2. 2) Upper Vindhyas: gently lying in undisturbed horizontal strata
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27
Q

Vindhyan system: rocks?

A

limestones, shales and sandstones

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28
Q

Vindhyan system: location?

A

(a) Sasaram and Rohtas in western Bihar to Chittaurgarh in Raj with a GAP in Bundelkhand. Large area of this belt is covered by deccan trap.
(b) also in Chhatisgarh, Bhima valley in KN; Kurnool of andhraP
(c) continue to the north under Gangetic alluvium and perhaps even under HImalayas
(d) Lower vindhyan : in Son valley; in chhatisgarh; in Bhima valley; Mewar
(e) Upper: KN

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29
Q

Vindhyan system: significance?

A

(a) upper Vindhyas: two diamond bearing horizons-panna and golconda diamond mines
(b) large qty of excellent and durable stones, flagstones, ornamental stones, glass making sand and some coal.

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30
Q

Dravidian system?

A

1) age: Palaeozoic; 600-300my
2) origin: -
3) characteristics: contains abundant fossils-helps in determining correct ages; coal formation started in Carboniferous period.
4) rocks:
4. 1) cambrian: slates, clays, quartzites and limestones
4. 2) Ordovician: quartzites, grits, sandstones and limestones
4. 3) Silurian: limes and shales
4. 4) Devonian: white quartzite; Muth quartzite of Spiti
4. 5) Carboniferous: limestone, shale and quartzite
5) location: mostly in extra-peninsular regions; conspicuous absence in Peninsula, except for rare patches near Umaria
5. 1) cambrian rock: best dev in NW Himalayan region; Haimanta system in Spiti valley of HP; Kullu and Lahul in HP; Baramula in J&K; salt range of Indo-pak border-saline series
5. 2) Ordovician: Spiti valley (overlying Haimanta series); Lidar valley in Kashmir; Kumaon region
5. 3) Silurian: Spiti valley; Kumaon region; thin stripein Lidar valley; Kullu and Lahul in HP
5. 4) Devonian: Spiti; Kumaon; Lidar valley; haridwar distr
5. 5) carboniferous: Mt. everest made up of upper carboniferous limestone; Spiti valley, Kashmir, Shimla and eastern HImalayas ; Pir Panjal trap and some in Kumaon region

31
Q

Dravidian system: age?

A

Palaeozoic; 600-300my

32
Q

Dravidian system: characteristics?

A

contains abundant fossils-helps in determining correct ages; coal formation started in Carboniferous period.

33
Q

Dravidian system: rocks?

A
  1. 1) cambrian: slates, clays, quartzites and limestones
  2. 2) Ordovician: quartzites, grits, sandstones and limestones
  3. 3) Silurian: limes and shales
  4. 4) Devonian: white quartzite; Muth quartzite of Spiti
  5. 5) Carboniferous: limestone, shale and quartzite
34
Q

Dravidian system: location?

A

mostly in extra-peninsular regions; conspicuous absence in Peninsula, except for rare patches near Umaria

  1. 1) cambrian rock: best dev in NW Himalayan region; Haimanta system in Spiti valley of HP; Kullu and Lahul in HP; Baramula in J&K; salt range of Indo-pak border-saline series
  2. 2) Ordovician: Spiti valley (overlying Haimanta series); Lidar valley in Kashmir; Kumaon region
  3. 3) Silurian: Spiti valley; Kumaon region; thin stripein Lidar valley; Kullu and Lahul in HP
  4. 4) Devonian: Spiti; Kumaon; Lidar valley; haridwar distr
  5. 5) carboniferous: Mt. everest made up of upper carboniferous limestone; Spiti valley, Kashmir, Shimla and eastern HImalayas ; Pir Panjal trap and some in Kumaon region
35
Q

Aryan rock system?

A
  • > Upper carboniferous to recent
  • > fairly preserved in Penin india
  • > found in perfect sequence in Himalayan region along entire Northern border
  • > sub-divisions:
    1) Gondwana system- Permian period
    2) Triassic system
    3) Jurassic system
    4) cretaceous system
    5) Tertiary system:
    5. 1) Deccan trap: palaeocene epoch of Tertiary period
    5. 2) eocene system
    5. 3) Oligocene and lower Miocene system
    5. 4) Shiwaik system: Middle Miocene to Lower Pleistocene
    6) quarternary:
    6. 1) Pleistocene
    6. 2) Recent
36
Q

Gondwana system?

A

1) age: Permian period; 250my
2) origin: continental origin; fluviatile and lacustrine deposits laid down in geosynclinal troughs on ancient plateau surfaces; embedded terrestrial plants and animals into fresh water and sub-aerial sediments
3) characteristics: flat sedimentary strata; some 6000m thick; shows several climate changes during its deposition; excessively deformed in extra-peninsular regions
4) rocks: sandstones with some shales and clays
5) location:
(a) damodar valley in JH
(b) mahanadi river valley in chh and Odisha
(c) southern part of MP
(d) series of troughs along Godavari frm nagpur t delta
(e) extra-penin: Kashmir, darjeeling and Sikkim
6) significance: 98% of INdia’s coal reserves; rich deposits of Iron ore, cu, U, Sb; Sandstones, slates and conglomerates are used as building material

37
Q

Gondwana system: age?

A

Permian period; 250my

38
Q

Gondwana system: origin?

A

continental origin; fluviatile and lacustrine deposits laid down in geosynclinal troughs on ancient plateau surfaces; embedded terrestrial plants and animals into fresh water and sub-aerial sediments

39
Q

Gondwana system: characteristics?

A

flat sedimentary strata; some 6000m thick; shows several climate changes during its deposition; excessively deformed in extra-peninsular regions

40
Q

Gondwana system:rocks?

A

sandstones with some shales and clays

41
Q

Gondwana system: location?

A

(a) damodar valley in JH
(b) mahanadi river valley in chh and Odisha
(c) southern part of MP
(d) series of troughs along Godavari frm nagpur t delta
(e) extra-penin: Kashmir, darjeeling and Sikkim

42
Q

Gondwana system: significance?

A

98% of INdia’s coal reserves; rich deposits of Iron ore, cu, U, Sb; Sandstones, slates and conglomerates are used as building material

43
Q

Triassic system?

A

1) almost unknown in Peinsular India but found extensively frm hazara to nepal
2) exposed on south flanks of GH frm Kashmir to Byans in eastern Kumaon
3) divided into lower, middle and upper divisions
4) limestones; calcareous strata

44
Q

Jurassic system?

A

1) overlies triassic in tibet, South Ladakh, Spiyi, Nepal and Bhutan; also found in Jaisalmer region; on the east coast, betn Guntur and Rajahmundry
2) shallow water deposits in Raj and Kachh due to marine transgressions in later Jurassic
3) Kachh: coral limestone,oolitic limestone, sandstone, conglomerates and shales

45
Q

cretaceous system?

A

1) one of the best developed marine system of India
2) wide variety of rocks, deposited on land, sea estuaries and lakes; no other system is so widely distributed in India
3) in both Penin and extra-penin india; Spiti; Kumaon; Rupshu and Burzil of Kashmir; plateaus of Meghalaya; Puducherry-thiruchirapalli; bagh beds in gwalior along Narmada valley, under the deccan traps; lemetas(estuarine and lacustrine deposits) in ccentral india

46
Q

deccan trap?

A

1) age: palaeocene epoch of Tertiary period
2) origin: volacanic outburst of extremely mobile baslat lava over an area of 10L sq km in Penin India
ne area reduced to half of it due to denudational processes
3) characteristics: these deposits hv flat top and steep sides, so appear as gigantic steps, so called ‘trap’; variable thickness- as much as 3000m along Mumbai coast, 800m in Katchh and only 150m at amarkantak
3.1) Upper trap: has numerous inter-trappean beds and layers of volcanic ash and avg thickness of 450m
3.2) Middle trap: numerous ashbeds bt devoid of inter-trappeans; avd thickness of 1200m
3.3) Lower trap: inter-trappean beds present but rare ash beds; avd thickness 150m
4) rock: basalt is the main rock bt also dolorite, rhyolite, gabro
5) location: present Deccan trap covers 5L km2; covers Kutchh, Saurashtra, MH, Malwa plateau and northern KN; parts of Telangana, TN, JH, UP
5.1) Upper trap: MH and saurashtra
5.2) Middle trap: central india and Malwa
5.3) Lower: central India and TN
6) significance:
6.1) great source of quartz, agate, calcite, building stones and road building material
6.2) regur soil

47
Q

Deccan trap: age?

A

palaeocene epoch of Tertiary period

48
Q

Deccan trap: origin?

A

volacanic outburst of extremely mobile baslat lava over an area of 10L sq km in Penin India
ne area reduced to half of it due to denudational processes

49
Q

Deccan trap: characteristics?

A

characteristics: these deposits hv flat top and steep sides, so appear as gigantic steps, so called ‘trap’; variable thickness- as much as 3000m along Mumbai coast, 800m in Katchh and only 150m at amarkantak
3. 1) Upper trap: has numerous inter-trappean beds and layers of volcanic ash and avg thickness of 450m
3. 2) Middle trap: numerous ashbeds bt devoid of inter-trappeans; avd thickness of 1200m
3. 3) Lower trap: inter-trappean beds present but rare ash beds; avd thickness 150m

50
Q

Deccan trap: rocks?

A

basalt is the main rock bt also dolorite, rhyolite, gabro

51
Q

Deccan trap: location?

A

present Deccan trap covers 5L km2; covers Kutchh, Saurashtra, MH, Malwa plateau and northern KN; parts of Telangana, TN, JH, UP

  1. 1) Upper trap: MH and saurashtra
  2. 2) Middle trap: central india and Malwa
  3. 3) Lower: central India and TN
52
Q

Deccan trap: significance?

A
  1. 1) great source of quartz, agate, calcite, building stones and road building material
  2. 2) regur soil
53
Q

Eocene system?

A

1) J&K: southern fland of Pir Panjal
2) Raj: lignite deposits
3) GJ: kutchh, surat and Broach areas
4) NE india:limestones and coal bearing areas of Jaintia hills; barail series in Surma valley and naga hills; coal deposits of upper assam
5) Some recently found in Pudducherry

54
Q

Oligocene and lower Miocene system?

A

1) very poorly develped in India, while Miocene system is fully developed
2) Rocks of Oligocene found in Barail series of assam
3) Miocene rocks found in all tertiary areas of extra-penin india eg. Murree series in jammu hills, Dagshai and kasauli series of Shimla area etc.

55
Q

Shiwalik system?

A
  1. Age: 14-0.2 my; Middle Miocene to lower Pleistocene
  2. origin: deposition in lagoons and freshwater lakes by the rivers of that time upto a thickness of 5000m
  3. characteristics: mostly non-fossiliferous but in certain areas, highly fossiliferous; variety of fossils- ranging frm humid forest fauna to arid region’s fauna
  4. rocks: sandstones, grits, conglomerates, clays and silts
  5. location:
    (a) found all along the shiwalik hills
    (b) Assam: Tipam and dihing series
    (c) Katchh and saurashtra
  6. significance: famous for oil resources , lignite, bauxite and clays of different varieties
56
Q

Shiwalik system: age?

A

14-0.2 my; Middle Miocene to lower Pleistocene

57
Q

Shiwalik system: origin?

A

deposition in lagoons and freshwater lakes by the rivers of that time upto a thickness of 5000m

58
Q

Shiwalik system: characteristics?

A

mostly non-fossiliferous but in certain areas, highly fossiliferous; variety of fossils- ranging frm humid forest fauna to arid region’s fauna

59
Q

Shiwalik system: rocks?

A

sandstones, grits, conglomerates, clays and silts

60
Q

Shiwalik system: location?

A

(a) found all along the shiwalik hills
(b) Assam: Tipam and dihing series
(c) Katchh and saurashtra

61
Q

Shiwalik system: significance?

A

famous for oil resources , lignite, bauxite and clays of different varieties

62
Q

Pleistocene and Indian physiography?

A

1) divided into 4 glacial and 3 inter-glacial periods by de terra and Paterson
2) during Glacial periods, sea level was lowered by 100m frm present level, resulting in much larger extension of land
3) first glacial and interglacial period belongs to lower pleistocene in Kashmir
4) Middle pleistocene bears witness of second glaciation and inter-glaciation: heavy depositions of boulder fans and fluvio-glacial deposits; formation of Karevas of Kashmir
5) Upper Pleistocene includes 3rd and 4th glaciations;
6) Pir Panjal was uplifted during 1st and 3rd glacial periods

63
Q

Karevas of Kashmir?

A
  1. formed due to heavy deposition of boulder fans and thick fluvio-glacial materials in the second glacial and interglacial periods of Pleistocene epoch
  2. these are flat topped terraces
  3. on the flanks of Pir-Panjal
  4. consists of clays, sands, silts together with lenticles of conglomerates frm old deltaic fans
64
Q

rocks/deposits of recent system?

A
  1. started 12000ya
  2. indo-gangetic alluviums
  3. bhangar: older; Middle or upper pleistocene age
  4. khadar: newer alluvium; upper pleistocene age
65
Q

Ice age in india?

A

1) dharwar ice age: reflected by conglomerates near Kaldurg in south India
2) Gondwana ice age: Talcher series of Gondwana system in Odisha provides proof of glaciation during this period; also in shimla, Hazara and salt range
3) Pleistocene ice age:
- > effect of ice age noticed in Himlayas; no evidence in penin india
- > not a continuous frigid spell but marked by cold and warm spells in succession
- > evidence of glaciation in Himalayas upto 1800m
- > de Terra and Peterson notices 4 or 5 periods of glaciation and inter-glacial periods in Kashmir
- > evidence of glaciation: rock polishing and grooving on lower steps of Himalayas, buff colored sands an luminated clays inter-stratified among karewa deposits, accumulations of marine debris on tops and sides of ranges of marine Himalayas which do not hv any glacier nw, ancient moraines found before the snouts of existing glaciers
- > has led to formation of no. of Glacial lakes like Kailash Kund, Gulmarg basin, sheshnag, Kaunsarmag;
- > glaciation has also led to sudden and large scale reduction in shiwalik mammals

66
Q

Processes of submergence and emergence have played an important role in sculpting India’s physical features, Elaborate.
OR
Evidences of submergence and emergence in India.

A
  1. most outstanding eg of submergence of sea coast: existence of submerged forest on eastern side of island of Mumbai, located at depths of 6-12m BSL; similar submergence seen on Tinnevelli coast
  2. A thick bed of lIgnite found in Pudducherry at 73m BSL; such submergence also found in Ganga dlta; recent discovery of ancient city of Dwarka under shallow waters off the coast of saurashtra
  3. Rann of Katchh has both the examples of submergence and emergence : submergence of area of >5000km2 due to EQ in 1819 while an area of >1500km2 was elevated; presence of coastal dunes, sea cliffs, sea caves within plains, raised beaches of littoral concrete on the fringes of the island
    4) uplift of coastal plain of Kerala: occurence of coral reefs below alluvium several km frm present coast; no. of lakes, backwaters and lagoons
    5) A&N, that were once connected to Arakan Yoma, nw stands separated; recent emergence of New Moore island in Ganga delta; submergence of Adam’s bridge betn india and sri Lanka
67
Q

faults and Fracture zones in India: Faults vs Fracture Zones vs Rifts?

A

Faults are cracks in the earth’s crust along which there is movement.

Fractures are simply cracks in the crust where there is no movement.

Rifts are narrow, long fissures developed in hard rock lands. Rift valley is a type of fault.

68
Q

faults and Fracture zones in India: Fault list?

A
  1. Paleo faults/rifts
    1. in Peninsular Plateau
  3. 1.1 Western Ghat fault/fracture that led to submergence of western coast of India
  4. 1.2. Great boundary Fault: to the east of Aravallis; It is along the geosyncline from which aravalli was formed; through it drains Chambal
  5. 1.3. narmada fault and tapi fault: Despite rich deposit of coal because of life trapped under sediments in the rift valleys, the overlying lava makes it uneconomical to exploit it
  6. 1.4. Son fault: from amarkantak to patna; Son river; Singrauli coal deposits
  7. 1.5. Koyana fault: Koyana river;
  8. 1.6. Kurdwari fault: in Latur and Osmanabad
  9. 1.7. east draining river faults
  10. 1.7.1. Damodar fault: coal deposits: raniganj, jharia, Giridih
  11. 1.7.2. Mahanadi fault: Talcher and Dhenkanal
  12. 1.7.3. Godavari fault: Ramagundam, Singreni coal deposits
  13. 1.7.4. Krishna fault: Ramagundam, Singreni coal deposits
  14. 1.7.5. Cauvery fault: called Great Mayur fault in KN and called Cauvery fault in Kerala; during aravalli-Tibet collision, Kerala and TN part of peninsular plateau was raised. Thus, Kerala WG is raised while KN and MH WG are reduced.
  15. Neo Faults
    1. in Peninsular Plateau
  17. 1.1. Delhi-Haridwar- harsil ridge
  18. 1.2. Malda gap rift
    1. in himalayas
  20. 2.1. Hinge line: GH and Tibet plateau are physically almost unseparable but structurally they are different. Tibet is a part of Angaraland and is called Tibet Shield or Tibet basal complex. It is very old igneous landmass. In comparison GH are young fold mountains. Hinge line separates the two structures
  21. 2.2. Main Central thrust (MCT): separates GH and MH. GH are of Eocene period while MH are of Miocene period.
  22. 2.3. Main Boundary Thrust: separates MH and Shivaliks. can be seen at Sahastradhara fall, Dehradun or at manora observatory
  23. 2.4. Himalayan Front Fault: Developing between Shivaliks and Terai. is a newly forming fault. observable especially in saharanpur region
  24. 2.5. Halflong fault and Naga thrust: All the three abovementioned Himalayan faults run parallel to himalayas and also bend at Namcha Barwa. The three are collectively called halflong fault in Arunachal Pradesh. From Nagaland onwards they are called Naga Thrust.
  25. 2.6. dauki fault and kopili fault: to the north of Meghalayan plateau lies Dauki fault and to its east lies Kopili fault through which flows the Kopili river.

The Delhi-Haridwar-Harsil faultline and Barren Is.-Malda Gap-Everest fault line are the newest fault lines developing in Indian subcontinent region that are tectonically active and experience tremors and quakes.

69
Q

faults and Fracture zones in India: causes of presence of so many faults in India?

A
  1. Geosynclines are bounded by faults. In India many mountain ranges have originated from geosynclines- like aravallis, Vindhyas, Satpura, himalayas. An thus they are bounded by faults
  2. Tensile and compressive forces at work during the various separation and collision of Indian plate.
70
Q

faults and Fracture zones in India: although there are rich deposits of coal in western and Central deccan region but coal mining is not practiced there. Why?

A

covered by a thick layer of lava. ~1400m thick

It decreases eastward and thus coal mines are on eastern side of peninsular plateau

71
Q

faults and Fracture zones in India: Along godavari and Krishna faults, there is rich deposit of coal in upper reaches while petroleum is found in lower reaches. why?

A

depends on pressure

As pressure bore by the submerged vegetation increases, coal, petroleum and gas are found respectively

Thus, on the western flanks, smaller fissures were there which led to coal formation while submerged vegetation in Krishna-Godavari basin faced extreme pressure and was converted to petroleum and natural gas

72
Q

faults and Fracture zones in India: bay of Cambay as node of faults?

A

Many faults emerged from bay of Cambay like

  • > Great boundary fault
  • > Narmada fault
  • > tapi fault
  • > Koyana fault
  • > Mahi fault
  • > Bhuj fault

This indicates very fast acting endogenetic forces in the region that radiated these many fault lines in all directions

Rich deposits of petroleum and natural gas
rich prospect of Geothermal energy
mouths of many rivers like mahi, narmada and tapi

also prone to EQs

73
Q

faults and Fracture zones in India: faults characteristics and nature of Himalyan region cannot be compared to that of Peninsular region. Why?

A

In peninsular India, rivers flow through faults while in Himalayan region most rivers are antecedent and instead of flowing parallel to faults, it cuts through the mountain ranges.

74
Q

faults and Fracture zones in India: coal deposits found in himalayan region?

A

Jangalgarhi deposits in Jammu

Namchik-Namphuk coal mine in Arunachal Pradesh

Indian Geography (13 decks)

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