Match List-I with List-II and select the correct answer using the code given below the Lists: List-I (Type of plain): A. Bhabar, B. Bhangar, C. Khadar, D. Delta List-II (Characteristic feature): 1. Marsh, 2. Silt, 3. Gravels, 4. Kankar

Correct — B, A-3, B-4, C-2, D-1. Walk the pairings one at a time down the slope. Bhabar is the narrow porous strip at the foot of the Shiwaliks where hill streams emerge on to the plain, drop the coarse load they were carrying and sink out of sight into it, so Bhabar goes with gravels, that is 3. Bhangar is the older alluvium standing above the flood level of the rivers; it is not renewed each year, and its weathered profile carries the lime concretions called kankar, so Bhangar goes with kankar, that is 4. Khadar is the newer alluvium of the flood plain itself, re-laid by fresh deposits every monsoon and therefore fine-grained, so Khadar goes with silt, that is 2. The delta is where the river meets the sea, its gradient falls away and its distributaries spread into tidal flats and swamp, so the delta goes with marsh, that is 1. That gives 3, 4, 2, 1 in order — option (b).

• (a)A-3, B-2, C-4, D-1 — It gets Bhabar and the delta right but swaps the middle pair, giving silt to Bhangar and kankar to Khadar. It is the older alluvium that carries kankar; the newer alluvium is the silty one.
• (c)A-1, B-4, C-2, D-3 — It exchanges the two ends, sending marsh to Bhabar and gravels to the delta. Coarse gravel is deposited where the gradient is steepest, at the mountain foot, not where a river is losing all its energy at the coast.
• (d)A-1, B-2, C-4, D-3 — This carries both errors together — the ends reversed as in (c), and the middle pair swapped as in (a). Nothing in it is correctly matched.

The northern plain is usually described as four belts running parallel to the mountains, and each belt is defined by the energy of the water that built it. Bhabar is coarse and permeable; the Terai just south of it is marshy because the streams that vanished into the Bhabar resurface there; Bhangar is the older, higher alluvium; Khadar is the low, freshly flooded newer alluvium; and the sequence ends in deltaic swamp at the coast.

The reliable method is to order the four items by grain size and let the geography follow, because a river sorts its load as it slows. Boulders and gravel are dropped first, at the break of slope; silt is carried far out on to the flood plain; the finest material and the tidal water end up in the delta. Kankar is the odd one out because it is not a transported grade at all — it forms in place, as calcium carbonate accumulates in an old soil profile, which is why it marks the terrace that the river no longer floods. Once kankar is tied to age rather than to grain size, Bhangar and Khadar stop being interchangeable.

• Bhabar is a belt roughly eight to sixteen kilometres wide along the Shiwalik foothills, built of pebbles and gravel, in which streams disappear underground.
• The Terai lies immediately south of the Bhabar and is marshy because those streams re-emerge there.
• Bhangar is the older alluvium, lying above the flood plain and containing calcareous nodules called kankar.
• Khadar is the newer alluvium of the flood plain, renewed by silt at each flood and the more fertile of the two.
• The Ganga-Brahmaputra delta ends in tidal marsh and mangrove, the Sundarbans being its best-known stretch.

• Swapping Bhangar and Khadar. Bhangar is older and higher and carries kankar; Khadar is younger, lower and silty.
• Treating kankar as a grain size like gravel or silt. It is a lime concretion that forms within an old soil.
• Confusing Bhabar with Terai. The streams vanish in the Bhabar and come back to the surface in the Terai.

As a match of plain type to feature, as a single question on where hill streams disappear, or as a comparison of Bhangar with Khadar.

• practice — not a real PYQ

  Kankar, the concretion used to identify one of the belts of the northern plain, is composed mainly of

  • (a)calcium carbonate
  • (b)iron oxide
  • (c)silica
  • (d)common salt

  Answer(a) calcium carbonate — it accumulates in the older alluvium of the Bhangar, which no longer receives fresh flood deposits.

• practice — not a real PYQ

  The marshy belt lying immediately south of the Bhabar, where the vanished hill streams reappear, is called

  • (a)Khadar
  • (b)Terai
  • (c)Bhangar
  • (d)Doab

  Answer(b) Terai — the water that sank into the porous Bhabar returns to the surface here.