INDIAN PHYSICAL GEOGRAPHY — Physiographic boundaries. Question: What is regarded as the principal dividing line between the geological regions of the Indo-Gangetic Plain and the Peninsular plateau of India?

Introduction / Context:
India’s physiography contrasts the alluvial, geologically younger Indo-Gangetic Plain with the ancient crystalline Peninsular plateau. Recognizing the boundary features is fundamental to understanding India’s geology, climate patterns, drainage, and soils.

Given Data / Assumptions:

• The Indo-Gangetic Plain lies to the north with extensive alluvium.
• The Peninsular plateau is to the south, older and structurally stable.
• We consider major ranges that align with the transitional zone.

Concept / Approach:
The Vindhya range runs east–west across central India and is widely cited as the cultural and geological divide between North India’s plains and the Peninsular plateau. While the Satpuras lie just south of the Vindhyas, and the Aravallis trend NE–SW in the west, the Vindhyas form the conventional marker separating the northern foreland basin from the Peninsular craton margins.

Step-by-Step Solution:
Locate the Indo-Gangetic Plain (north) and the Peninsular plateau (south).Identify the east–west range marking their boundary → the Vindhyas.Eliminate ranges that do not align with this boundary (Nilgiri, Western Ghats—southern/western peninsular; Aravallis—northwest; Satpuras—south of Vindhyas).

Verification / Alternative check:
Standard school atlases and geology texts annotate the Vindhya range as the classic dividing line, with the Narmada–Tapi rift further south between Vindhyas and Satpuras.

Why Other Options Are Wrong:
B) Aravallis separate parts of Rajasthan; not the primary Indo-Gangetic vs Peninsular divide.C) Nilgiris lie in the south at the junction of Western and Eastern Ghats.D) Satpuras are south of Vindhyas; not the conventional boundary line.E) Western Ghats bound the western plateau margin, not the north–south divide in question.

Common Pitfalls:
Confusing nearby ranges (Vindhyas vs Satpuras). Remember: Vindhyas form the immediate divide above the Narmada valley.

Final Answer:
the Vindhya range