MPPSC 2023 Prelims Paper-I · Question 60 of 100

Correct — C, Mizoram. Mizoram's hill ranges are part of the young, actively rising Indo-Burman (Purvanchal) fold mountains, built up of thick Tertiary sedimentary rocks — sandstones and shales eroded off the rising ranges and deposited in the adjoining trough. Because these deposits are geologically classed as 'molasse' (soft, poorly consolidated sediment shed from a young orogenic belt), the region is also referred to as the Molasse Basin.

• (a)Manipur — Also part of the hilly north-eastern Indo-Burman ranges, but it is Mizoram, not Manipur, that carries the 'Molasse Basin' label.
• (b)Tripura — Also built of young Tertiary hill ranges in the north-east, but the 'Molasse Basin' designation is specifically applied to Mizoram, not Tripura.
• (d)Nagaland — Home to the Naga Hills, another part of the same Indo-Burman fold-mountain system, but again it is Mizoram, not Nagaland, that carries the 'Molasse Basin' name.

'Molasse' is a geological term for the soft, poorly consolidated sedimentary rocks (sandstone, shale, conglomerate) shed by erosion from a young, actively rising fold-mountain belt and deposited in an adjoining basin. Mizoram — part of the Indo-Burman/Purvanchal ranges formed by the same tectonic collision that built the Himalayas — is composed of such young Tertiary sedimentary sequences, which is why the region is also known as the Molasse Basin.

This is a niche physical-geography/geology fact about the north-eastern hill states; the trap is that all four options (Manipur, Tripura, Mizoram, Nagaland) are genuine, similar-looking Indo-Burman hill states, so only knowing the specific 'Molasse Basin' label picks out the correct one.

• 'Molasse' = soft, poorly consolidated sediment (sandstone/shale) eroded from a young rising mountain belt
• Mizoram is also known as the Molasse Basin
• Mizoram's hills are part of the Indo-Burman (Purvanchal) fold-mountain system, geologically young (Tertiary)
• Manipur, Tripura and Nagaland are neighbouring Indo-Burman hill states but do not carry this specific label

• Assuming any north-eastern hill state could be called the 'Molasse Basin' since they share similar young fold-mountain geology
• Confusing 'molasse' (coarse erosional sediment from a rising range) with 'flysch' (deep-marine sediment deposited before/during mountain uplift)

A direct 'which state/region is also called X' nickname question, common for physical-geography nicknames in the north-east (e.g., 'Molasse Basin' for Mizoram, 'Scotland of the East' for Meghalaya).

No directly related past PYQ was found.

• practice — not a real PYQ

  Mizoram's hill ranges are part of which major fold-mountain system of North-East India?

  • (a)Himalayan range proper
  • (b)Indo-Burman (Purvanchal) ranges
  • (c)Deccan Plateau uplands
  • (d)Aravalli range

  Answer(b) Indo-Burman (Purvanchal) ranges — the same Tertiary collision belt that also built the Naga and Manipur hills.

• practice — not a real PYQ

  In geology, 'molasse' refers to:

  • (a)Deep marine sediment deposited before mountain uplift
  • (b)Soft, poorly consolidated sediment eroded from a rising young mountain belt
  • (c)Igneous rock formed from cooled lava
  • (d)Metamorphic rock formed under extreme pressure

  Answer(b) Soft, poorly consolidated sediment eroded from a rising young mountain belt — the erosional product that gives Mizoram its 'Molasse Basin' name.