Which one of the following pairs (Deccan Trap – Peculiarity) is not correctly matched ?

Question

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Correct — B, Intertrappean beds – Fossils of sea plants and animals. The intertrappean beds are the thin sedimentary layers sandwiched between successive basalt flows of the Deccan Trap. They formed in the quiet intervals between eruptions, when a lava sheet cooled, weathered and ponded water, so that shallow lakes, ponds and streams spread across the plateau surface and laid down silt, clay and limestone before the next flow buried them. Everything that lived in those pools was therefore a land-and-freshwater community, and that is exactly what the beds preserve: freshwater molluscs and gastropods, charophyte algae, ostracods, fish, and the remains of early frogs such as Indobatrachus, along with plant material. They are not marine deposits and they do not carry fossils of sea plants and animals — the sea never covered the erupting lava plateau. The same is true of the infratrappean beds below the lavas, the Lameta Formation, whose freshwater and fluvial sediments are famous instead for dinosaur remains. So the peculiarity attached to the intertrappean beds in option (b) is the one that is false, and (b) is the marked answer. A note on honesty about the other three options. The metre figures for the lower, middle and upper traps are the numbers carried by the classical three-fold division of the Deccan Trap used in Indian geology and geography textbooks, and the commission has drawn the question from that source; the examiner treats them as correct. Published estimates of Deccan thickness vary a great deal from place to place — the whole pile exceeds two kilometres near the west coast and thins eastwards — so we reproduce the textbook figures as the examiner's, rather than vouching for the precise metres. Nothing turns on them here: the deliberate falsifier the setter planted is the word 'sea'.

Why the other options are wrong — (a) Treated as correctly matched, so it cannot be the answer. The Deccan Trap is divided stratigraphically into Lower, Middle and Upper traps, and about 1,200 metres is the thickness the standard Indian textbook account gives the middle division — the thickest of the three. It is worth knowing that thickness measurements vary widely across the province, the full lava pile being more than two kilometres thick near the western margin and thinning towards the east, so treat these as the classification's conventional figures rather than a single measured number.  (c) Treated as correctly matched. About 150 metres is the figure the same three-fold division attaches to the lower traps, the thinnest of the three divisions and the earliest to be erupted. Note that the traps are not measured like a single sheet: each division is a stack of many individual flows, and it is the flows piled one on another that give the formation its stepped or staircase profile.  (d) Treated as correctly matched. About 450 metres is the conventional figure for the upper traps, the youngest of the three divisions.

Concept: The Deccan Traps are one of the world's great flood-basalt provinces. Enormous volumes of runny basaltic lava poured out of long fissures, not from a single cone, and spread as near-horizontal sheets one on top of another. The eruptions occurred over a period of roughly 600,000 to 800,000 years, about 66.3 to 65.6 million years ago, straddling the Cretaceous–Palaeogene boundary and so overlapping the extinction of the dinosaurs. The lavas cover about 500,000 square kilometres of western and central India today and originally may have covered around 1.5 million square kilometres; the pile is more than two kilometres thick near the west coast. The name comes from the Scandinavian word for a stair or step, because differential weathering of the stacked flows carves the characteristic terraced hillsides seen across Maharashtra and the northern Western Ghats. Weathering of this basalt in situ produces the regur or black cotton soil that made the Deccan India's cotton belt.

State PCS 2024 Q59 — Geography PYQ with Answer

State PCS 2024 Q59 — Geography PYQ with Answer