Question
Which of the following geographical features or phenomena is/are associated with the Peninsular Block of India?
1
Submergence of parts of the western coast due to tectonic activity.
2
Presence of residual mountain ranges such as the Veliconda hills and Mahendragiri hills.
3
Deep, V-shaped river valleys formed by fast-flowing rivers.
A1 only
B1 and 2
C2 and 3
D3 only
📚 Source — NCERT Class 11 India Physical Environment, Chapter 2: Structure and Physiography
“Since the Cambrian period, the Peninsula has been standing like a rigid block with the exception of some of its western coast which is submerged beneath the sea and some other parts changed due to tectonic activity without affecting the original basement. The Peninsula mostly consists of relict and residual mountains like the Aravali hills, the Nallamala hills, the Javadi hills, the Veliconda hills, the Palkonda range and the Mahendragiri hills , etc. The river valleys here are shallow with low gradients. ”
Each Statement — Verified from NCERT
1
“Submergence of parts of the western coast due to tectonic activity” — TRUE
NCERT (Class 11, Chapter 2) states verbatim: “the Peninsula has been standing like a rigid block with the exception of some of its western coast which is submerged beneath the sea and some other parts changed due to tectonic activity.”
Submergence of parts of western coast due to tectonic activity
✓ Correct — verbatim NCERT
What happened geologically:
• During the Early Tertiary period, the western flank of the Peninsular Block underwent tectonic subsidence (vertical sinking)
• This caused parts of the western coast to submerge beneath the sea
• This disrupted the original symmetrical drainage pattern of the Peninsula — the rivers that originally flowed westward were disturbed, and the drainage was tilted eastward
• This is why most peninsular rivers now drain eastward into the Bay of Bengal rather than westward
✓ Verbatim NCERT — Chapter 2
Western coast submergence + tectonic activity = explicitly described in NCERT. Also explains why most peninsular rivers flow east, not west.
2
“Residual mountain ranges such as the Veliconda hills and Mahendragiri hills” — TRUE
NCERT explicitly lists both hills as residual/relict mountain examples of the Peninsular Block: “The Peninsula mostly consists of relict and residual mountains like the Aravali hills, the Nallamala hills, the Javadi hills, the Veliconda hills, the Palkonda range and the Mahendragiri hills, etc.”
Residual mountains — Veliconda hills & Mahendragiri hills
✓ Correct — verbatim NCERT
What are residual/relict mountains? These are the remnants of once-massive ancient mountain systems that have been worn down over hundreds of millions of years by erosion — they are the “survivors” of ancient orogeny, now reduced to hills and low ranges. They reflect the immense geological age of the Peninsular Block.
Location of these hills:
• Veliconda hills — Andhra Pradesh, south of the Nallamala range
• Mahendragiri hills — on the Odisha-Andhra Pradesh border; second highest peak in Odisha (~1,501 m)
✓ Verbatim NCERT — Chapter 2
NCERT complete list: Aravali · Nallamala · Javadi · Veliconda · Palkonda · Mahendragiri — all residual/relict mountains of the Peninsular Block
3
“Deep, V-shaped river valleys formed by fast-flowing rivers” — WRONG — this describes Himalayan rivers
NCERT is explicit and direct: “The river valleys here are shallow with low gradients.“
“Deep, V-shaped valleys formed by fast-flowing rivers”
✗ This describes HIMALAYAN rivers — not Peninsular
Why peninsular rivers have SHALLOW valleys:
• The Peninsular Block is an ancient, stable, rigid landmass that has been undergoing slow erosion since Precambrian times
• Peninsular rivers flow over a nearly flat, ancient plateau that has had millions of years to erode into a peneplain
• They are in an old age stage of the erosional cycle — gradients are gentle, valleys are wide and shallow
• East-flowing peninsular rivers form deltas at their mouths (Mahanadi, Godavari, Krishna, Kaveri) — evidence of sediment deposition, not deep erosion
V-shaped valleys = Himalayan feature:
• The Himalayas are young mountains, still rising
• Himalayan rivers have steep gradients and fast flow → actively cutting downward → deep V-shaped gorges
• Examples: Indus Gorge, Brahmaputra Gorge, Sutlej at Shipki La
✗ NCERT says the opposite — shallow, low gradient
Peninsular rivers = SHALLOW valleys + LOW GRADIENTS. Deep V-shaped valleys = HIMALAYAN rivers (young, active uplift, steep gradients). Statement 3 attributes Himalayan characteristics to peninsular rivers.
Peninsular vs Himalayan Rivers — The Classic Contrast
🏔️ Peninsular Rivers (correct for this question)
Valley shape: Wide and shallow · old-stage erosion
Gradient: Low — gentle slope across ancient plateau
Flow: Relatively calm in middle/lower courses
Drainage pattern: Mostly eastward → Bay of Bengal (due to western coast submergence)
Mouth: Form deltas (Mahanadi, Godavari, Krishna, Kaveri)
Water source: Seasonal (rain-fed) — only rainfall dependent
🏔️ Himalayan Rivers (Statement 3 describes THESE)
Valley shape: Deep, V-shaped gorges — active downcutting
Gradient: Steep — fast-flowing, turbulent in upper courses
Flow: Fast and powerful — erosional in upper course
Drainage: Antecedent — predate Himalayan uplift
Mouth: Form estuaries (Indus, Ganga-Brahmaputra in parts)
Water source: Perennial — glacier + snowmelt + rainfall
Key Facts — Peninsular Block of India
| Feature | Detail |
| Geological age | Precambrian (Archaean gneisses and granites) — one of the oldest landmasses on Earth · Cambrian period onwards = stable rigid block |
| Western coast | Submerged due to tectonic subsidence (Early Tertiary) · Disrupted original symmetrical drainage pattern |
| Residual mountains | Aravali · Nallamala · Javadi · Veliconda · Palkonda · Mahendragiri — all remnants of ancient mountain systems, worn down by erosion |
| River valleys | SHALLOW with LOW GRADIENTS — NOT deep or V-shaped. V-shaped valleys = Himalayan characteristic. |
| Tectonic events | Rift valleys of Narmada, Tapi, Mahanadi · Satpura block mountains · Block faulting · Vertical movements |
| Plate | Part of the Indo-Australian Plate · Ancient shield — stable and rigid |
| Drainage | Most rivers drain eastward (Bay of Bengal) due to western coast submergence tilting the drainage system · Notable exception: Narmada, Tapi (westward rift valley rivers) |
| River mouths | East-flowing rivers form deltas — Mahanadi, Godavari, Krishna, Kaveri |
| NCERT source | Class 11 India Physical Environment, Chapter 2: Structure and Physiography (verbatim) |
Memory Trick — Never Forget This
🧠 Remember It This Way
Statement 3 trap — Peninsula = OLD = SHALLOW: The Peninsular Block is ancient (Precambrian). Old rivers erode over millions of years to produce wide, flat, shallow valleys. Deep V-shaped valleys = YOUNG mountains (Himalayas) = active cutting. Old plateau = gentle, shallow valleys.
NCERT quote to memorise: “The river valleys here are shallow with low gradients.” This is the direct opposite of Statement 3. When you see “V-shaped” or “fast-flowing” for peninsular rivers → immediately mark wrong.
Residual hills list (NCERT exact): Aravali → Nallamala → Javadi → Veliconda → Palkonda → Mahendragiri. Learn this sequence. UPSC picks any two from this list and tests whether students know they are all residual/relict mountains of the Peninsular Block.
Western coast submergence = why rivers flow east: The tectonic subsidence of the western coast tilted the entire drainage system eastward. This is why most peninsular rivers drain to the Bay of Bengal — Mahanadi, Godavari, Krishna, Kaveri. The westward rivers (Narmada, Tapi) flow through rift valleys — different mechanism.
