Match the following :
Column I
(a) Dome-shaped Plateau
(b) Volcanic Plateau
(c) Step-like Plateau
(d) Piedmont Plateau
Column II
(i) Deccan Plateau
(ii) Vindhya Plateau
(iii) Chota Nagpur Plateau
(iv)

Question

Match the following :
Column I
(a) Dome-shaped Plateau
(b) Volcanic Plateau
(c) Step-like Plateau
(d) Piedmont Plateau
Column II
(i) Deccan Plateau
(ii) Vindhya Plateau
(iii) Chota Nagpur Plateau
(iv) Shillong Plateau

UnlockIAS · Accepted Answer

Correct — option (3). Column I names four types of plateau and Column II four Indian plateaus, and the columns are printed side by side only because the page is set that way; the pairing has to be built. Build it from the one pairing that admits of no argument. The volcanic plateau at (b) can only be the Deccan at (i): the Deccan plateau is built of horizontal sheets of basalt poured out in the great eruptions of the late Cretaceous, the flows known as the Deccan Traps, and no other plateau in this list is of volcanic origin at all. That single pairing decides the question, because option (3) is the only row that makes it, and it is worth noticing that a candidate who is unsure of the other three can still answer the item with complete confidence on this one. The remaining pairings follow. The step-like plateau at (c) goes to the Vindhya at (ii), whose horizontally bedded Vindhyan sandstones weather back into a succession of terraces and scarps between the Ganga plain and the Narmada-Son trough. The dome-shaped plateau at (a) goes to the Chota Nagpur at (iii), whose surface is arched up in the middle, the land falling away in steps on every side from the higher pat surfaces of the interior. The piedmont plateau at (d) goes to the Shillong plateau at (iv); a piedmont plateau is by definition one lying at the foot of a mountain range, and the classification this paper follows places the Shillong plateau, which stands beyond the Brahmaputra valley below the eastern Himalayan front, in that class. The completed pairing is (a)-(iii), (b)-(i), (c)-(ii), (d)-(iv), which is option (3).

Why the other options are wrong — (a) This row gives the volcanic plateau to Chota Nagpur, and that is enough to end it. The Chota Nagpur plateau is part of the ancient crystalline shield of the peninsula — granites, gneisses and the folded rocks of the Dharwar and Gondwana systems, which is why it carries the country's greatest concentration of coal, iron ore, mica and bauxite — and it has no relation to the lava flows of the Deccan. The row then gives the dome-shaped description to the Deccan and the step-like one to Shillong. Its usefulness for revision is that it shows how quickly a matching item collapses when the least ambiguous clue is tested first: volcanic can belong to exactly one Indian plateau, so any row that spends that clue elsewhere is finished before the other three pairs are read.  (b) This row gives the volcanic plateau to Shillong and the dome-shaped one to the Vindhya, and neither can stand. The Shillong or Meghalaya plateau is a detached block of the peninsular shield, separated from the main mass by the gap in which the Ganga and Brahmaputra flow, and it is built of the same ancient crystalline rocks; it carries the Garo, Khasi and Jaintia hills, with Mawsynram and Cherrapunji on the steep southern slopes that face the monsoon. Nothing in it is volcanic. The Vindhya, for its part, is a sequence of horizontally bedded sandstones and limestones, and horizontal beds erode into steps and scarps rather than into a dome. The row inverts almost every relation in the question and can be discarded on the Deccan pairing alone.  (d) This row gives the volcanic plateau to the Vindhya, which reverses the two central pairings of the question, and it is the row a candidate is likeliest to reach if he has learnt that the Deccan has a step-like appearance. That is not wrong as a description — the Deccan Traps take their name from a word meaning step, because the successive lava flows weather back into a staircase profile — but a matching item allows each clue to be used once, and volcanic can belong to no Indian plateau except the Deccan while step-like can also describe the terraced Vindhyan sandstones. When two clues could both fit one item, give it the clue that fits it uniquely and let the other clue go to the item that can still take it. This row also gives the piedmont description to Chota Nagpur and the dome to Shillong.

Concept: Plateaus are classified in two ways and Indian examples are used for both. The first classification is by origin. A volcanic or lava plateau is built by successive flows of fluid basalt spreading over the surface, of which the Deccan is the Indian instance and the Columbia plateau of the United States the foreign one. An intermontane plateau lies enclosed within mountain ranges, as Tibet does between the Himalaya and the Kunlun. A piedmont plateau lies at the foot of a mountain range, the name meaning exactly that, with the Piedmont plateau of the eastern United States below the Appalachians and the Patagonian plateau below the Andes as the standard examples. A continental or tableland plateau rises directly from the plains or the sea. The second classification is by form, and it is the one from which the dome-shaped and step-like descriptions come: an upwarped block whose surface arches in the middle is called dome-shaped, while horizontally bedded sedimentary rock eroded into terraces and scarps gives a step-like profile. The Indian peninsular plateau, the oldest and most stable landmass in the country, contains examples of several of these at once — the lava-covered Deccan in the west and centre, the sandstone country of the Vindhya and Bundelkhand to the north, the mineral-bearing Chota Nagpur block to the east, and the detached Shillong plateau beyond the Ganga and Brahmaputra gap.

State PCS 2022 Q14 — Geography PYQ with Answer

State PCS 2022 Q14 — Geography PYQ with Answer