Chotanagpur plateau

Geography glossary

Also called: Chhota Nagpur Plateau · Topic: Structure and Physiography of India: Himalayas, Plains, Peninsula, Coasts and Islands · NCERT: Class 6, Ch 3 "Landforms and Life"; Class 11, Ch 2 "Structure and Physiography"; Class 11, Ch 3 "Drainage System"; Class 11, Ch 4 "Climate"

Meaning

The Chotanagpur plateau (also spelt Chhota Nagpur Plateau) is the north-eastern part of the Peninsular Plateau. It lies mainly in Jharkhand and spreads into Chhattisgarh, Odisha, West Bengal and Bihar. It is made up of the Hazaribagh, Ranchi and Palamu plateaus.

  • It is India's richest mineral store. It holds coal, iron ore, mica and bauxite.
  • These minerals support India's steel and power industries. This is why the plateau comes up again and again in questions on landforms, minerals and industry.

Explanation

Position within the Peninsular Plateau

  • The Peninsular Plateau is a large, raised block of very old, hard rock shaped like an irregular triangle. It is part of the ancient Archaean block (rocks more than 2.5 billion years old). This block once belonged to Gondwana, the old southern supercontinent.
  • Chotanagpur lies at its north-eastern corner:
  • To its north-east are the Rajmahal hills. These are the eastern limit of the whole Peninsular Plateau. The Chotanagpur plateau lies to their south.
  • To the west, the Maikal range links the Satpura range with Chotanagpur.
  • To the north-east, past the Malda gap, lies the Meghalaya (Shillong) plateau. The Malda gap is a low area made by faulting and later filled with river silt. The Meghalaya plateau belongs to the same old rock block.

Parts: a patland plateau of "pats"

  • Patland plateau: a plateau made of flat-topped, step-like surfaces at different heights.
  • Cause: very long erosion over millions of years.
  • Process: the land is slowly worn down until its tops become level.

  • Result: each "step" is a separate flat plateau surface.

  • Its three main parts are the Hazaribagh, Ranchi and Palamu plateaus, all in Jharkhand.

  • In this region the flat tops are called pats. One example is the Netarhat pat.
  • Highest peak: Parasnath (about 1,365 m).
  • Other plateau landforms found here:
  • Tors: piles of rounded rock blocks left standing after granite weathers along its cracks.
  • Hummocky hills: low, rounded, uneven hills.
  • Bare rocky surfaces: exposed rock with little soil.
  • Quartzite dykes: wall-like bands of hard rock that act as natural dam walls and store water behind them.

Why it is so rich in minerals: the Damodar rift

  • Cause: the Peninsular Plateau has gone through repeated uplift, sinking, faulting and fracturing.
  • Process: the crust stretched and broke along two parallel faults, and the middle block dropped down. This made a rift valley (a long, narrow valley that has sunk between two faults).

  • The Damodar river flows east through this rift valley in the Chotanagpur plateau.

  • Result: old Gondwana rocks were preserved inside this sunken trough. They hold India's main coal fields, such as Jharia and Bokaro in Jharkhand and Raniganj on the West Bengal side.

  • The very old Archaean rocks around the trough also hold iron ore, mica and bauxite.

Where it occurs

  • States: mainly Jharkhand. It extends into Chhattisgarh, Odisha, West Bengal and Bihar.
  • Component plateaus: Hazaribagh, Ranchi, Palamu (Jharkhand). The Netarhat pat is a well-known flat top.
  • Highest point: Parasnath (about 1,365 m).
  • River: the Damodar flows east through a rift valley across the plateau.
  • Coal fields in the Damodar trough: Jharia, Bokaro (Jharkhand) and Raniganj (West Bengal).
  • Neighbours:
  • Rajmahal hills (Jharkhand) to the north-east.
  • Maikal range (Madhya Pradesh–Chhattisgarh border) to the west, linking it to the Satpuras.

  • Malda gap, separating the main plateau from the Meghalaya plateau.

  • Similar patland plateaus elsewhere in India: Malwa (Madhya Pradesh), Coimbatore (Tamil Nadu) and the Karnataka plateau.

Don't confuse with

  • Rajmahal hills: these are basalt lava hills (the Rajmahal traps) and mark the eastern limit of the Peninsular Plateau. The Ganga bends around them. Chotanagpur is the mineral-rich patland plateau that lies to their south.
  • Malwa plateau: a lava plateau in western Madhya Pradesh covered by Deccan basalt. Its black soil suits cotton and soybean. Chotanagpur is known for minerals (coal, iron ore, mica, bauxite), not black soil. Both are patland plateaus.
  • Meghalaya (Shillong) plateau: it belongs to the same old rock block, but it is cut off from the main plateau by the Malda gap. It is a north-eastern extension, not part of Chotanagpur.
  • Narmada–Tapi rift valleys vs the Damodar rift: the Narmada and Tapi flow west in their rifts into the Arabian Sea. The Damodar flows east through its rift in Chotanagpur. Gondwana coal lies in the Damodar trough.

Prelims Hooks

  • Hazaribagh, Ranchi and Palamu plateaus together make up the Chotanagpur plateau, mainly in Jharkhand.
  • Pats are the flat tops of Chotanagpur's patland plateaus. Example: Netarhat pat.
  • Highest points, in order: Guru Shikhar (Aravalli, about 1,722 m) > Parasnath (Chotanagpur, about 1,365 m) > Dhupgarh (Satpura, about 1,350 m).
  • Damodar = a rift valley river flowing east across Chotanagpur. Its Gondwana trough holds the Jharia, Bokaro and Raniganj coal fields.
  • Raniganj coal field is in West Bengal, not Jharkhand. This is a common trap.
  • The Maikal range links the Satpura range with the Chotanagpur plateau.

Mains Points

  • Landforms drive resources (GS-I/III):
  • Faulting created the Damodar rift, and old Gondwana rocks survived inside it. These rocks hold India's main coal fields (Jharia, Bokaro, Raniganj).
  • The surrounding old rocks also give iron ore, mica and bauxite.

  • Coal and iron ore found close together make this plateau the base of India's steel and power industries.

  • An old block that still changes (GS-I): Chotanagpur is part of the stable Archaean block. Even so, repeated uplift, faulting and long erosion shaped its rift valley, its step-like pats and its tors, dykes and bare rocky surfaces. The plateau is therefore a good example of how old rocks keep changing over time.

  • Water in a hard-rock plateau (GS-III): bare rock and thin soil hold little water. Quartzite dykes act as natural dam walls, so they make good sites for storing water in this hard-rock region.

Related concepts

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Sources

  1. 1Class 6, Ch 3 "Landforms and Life"; Class 11, Ch 2 "Structure and Physiography"; Class 11, Ch 3 "Drainage System"; Class 11, Ch 4 "Climate" (primary)