NDA Geography · Earth's Structure, Landforms and Geological Time
Landforms and Mass Movements
Each gradational agent — rivers, glaciers, wind, the sea and underground water — carves its own signature erosional and depositional landforms, while gravity drives rock and soil downslope as mass movements.
Why this matters
15 PYQs. The skill is matching a landform to its AGENT: oxbow lake → river, drumlin → glacier, barchan → wind, sea stack → waves, stalactite → underground water. Most traps are 'which is NOT a depositional/erosional feature' or 'which agent made this' — learn the landform-by-agent table and the mass-movement triggers.
Concept 1 of 6: Mountains and plateaus by origin
Mountains are classified by HOW they formed. Fold mountains are crumpled at convergent boundaries (Himalayas, Alps, Andes, Rockies). Block mountains are uplifted between faults. Volcanic mountains are built of erupted material (Fuji). Residual mountains are the worn-down stumps of old ranges (Aravalli).
Definition
- Fold mountains — buckled by compression at convergent boundaries: Himalayas, Alps, Andes, Rockies.
- Block mountains — uplifted between faults (horst): Sierra Nevada, Vosges, Black Forest.
- Volcanic mountains — built of lava/ash: Mount Fuji, Vesuvius, Mauna Loa.
- Residual mountains — erosion remnants of old ranges: Aravalli (among the world's oldest).
- Plateaus: intermontane (Tibet), piedmont (Patagonia), volcanic/lava (Deccan).
| Mountain type | Origin | Example |
|---|---|---|
| Fold | Compression at convergent boundary | Himalayas, Alps, Andes, Rockies NDA 2023 — Alps, Andes, Rockies are fold mountains; Mt. Fuji is NOT. |
| Block | Faulting (uplifted block) | Sierra Nevada, Black Forest |
| Volcanic | Lava / ash build-up | Mount Fuji, Vesuvius |
| Residual | Erosion remnant | Aravalli |
Practice this conceptself-check · 3 quick reps
The same idea in a real exam question:
NDA · Sep 2023 · Q123Easy
Example 1 · Earth's Structure, Landforms and Geological Time · Landforms and Mass Movements
Which one of the following is NOT an example of Fold Mountain?
Concept 2 of 6: River (fluvial) landforms
A river erodes in its youthful, steep upper course and deposits in its old, flat lower course. Upstream it cuts gorges, canyons and potholes; as it matures it swings into meanders that pinch off into oxbow lakes; near the sea it dumps its load as levees and a delta. Match the feature to the stage and the agent is obvious.
Definition
- Erosional (upper course): V-shaped valley, gorge, canyon (a deep valley with steep step-like sides), potholes, waterfalls.
- Depositional (lower course): oxbow lake (cut-off meander — needs both erosion AND deposition), natural levee, floodplain, delta.
- Delta features: chars are the uplands/islands of a delta region; Paradeep Port sits on the Mahanadi delta.
| Landform | Type | Where |
|---|---|---|
| Gorge / Canyon | Erosional | Upper course |
| Oxbow lake | Erosion + deposition | Middle/lower course NDA 2021 — an oxbow lake results from both erosion and deposition by a river. |
| Delta, levee | Depositional | Lower course / mouth |
Practice this conceptself-check · 3 quick reps
The same idea in a real exam question:
NDA · Sep 2021 · Q85Easy
Example 2 · Earth's Structure, Landforms and Geological Time · Landforms and Mass Movements
Which one of the following features is the result of erosion and deposition work of a river?
Concept 3 of 6: Glacial landforms
Moving ice grinds out its own set of features. It scoops armchair hollows (cirques) and U-shaped valleys, and it dumps debris as moraines, eskers and drumlins. The drumlin — a smooth, egg-shaped mound of glacial till — gives a field of them the nickname 'basket-of-eggs' topography.
Definition
- Erosional: cirque (armchair hollow), U-shaped valley, arete, horn, fjord.
- Depositional: moraine (rock debris), esker (winding ridge), drumlin (smooth egg-shaped mound of till).
- A field of drumlins looks like a 'basket-of-eggs' topography.
| Landform | Type |
|---|---|
| Cirque, U-valley, fjord | Erosional |
| Drumlin | Depositional ('basket-of-eggs') NDA 2021 — basket-of-eggs topography = drumlins. |
| Esker, moraine | Depositional |
Practice this conceptself-check · 2 quick reps
The same idea in a real exam question:
NDA · Apr 2021 · Q119Moderate
Example 3 · Earth's Structure, Landforms and Geological Time · Landforms and Mass Movements
Basket-of-eggs topography is related to
Concept 4 of 6: Desert (arid / wind) landforms
In deserts, wind and rare flash floods are the sculptors. Wind piles sand into crescent dunes called barchans, and the dry beds of short-lived desert lakes harden into flat playas. These are ARID landforms — a category of their own, not fluvial or glacial.
Definition
- Barchan — a crescent-shaped sand dune formed by wind blowing steadily from ONE direction; its horns point DOWNWIND (the way the wind blows), and the windward slope is gentle (not steep).
- Playa — the fine-grained bed of an ephemeral (temporary) desert lake; it occupies the lowest part of a basin (bolson). It is an arid landform.
- Other wind features: yardangs, mushroom (pedestal) rocks.
| Landform | What it is |
|---|---|
| Barchan | Crescent wind-blown dune; horns point downwind NDA 2024 — barchan is a crescent dune from a one-direction wind (only that claim is fully correct). |
| Playa | Bed of a temporary desert lake (arid landform) NDA 2021 & 2024 — playa = fine-grained ephemeral-lake bed in a bolson; an ARID landform. |
Practice this conceptself-check · 2 quick reps
The same idea in a real exam question:
NDA · Sep 2021 · Q54Easy
Example 4 · Earth's Structure, Landforms and Geological Time · Landforms and Mass Movements
Fine-grained bed of ephemeral lake in a desert is also known as
A playa is an ARID landform, not fluvial
Because a playa holds water occasionally, students file it under fluvial/lake landforms. It is classified as an arid landform — it occupies the floor of a desert basin (bolson).
Concept 5 of 6: Coastal and karst landforms
Waves attack a coast (erosion) and also build it up (deposition). Erosion cuts notches, sea caves, arches, stacks and cliffs; deposition builds beaches, spits, bars and tombolos. Separately, underground water dissolving limestone (karst) hangs stalactites from cave roofs and grows stalagmites from the floor.
Definition
- Coastal EROSIONAL: notch, sea cave, sea arch, stack, cliff, hook (a stack is erosional — wave-cut).
- Coastal DEPOSITIONAL: beach, spit, sand bar, tombolo.
- Karst (underground water): dissolving limestone forms caves, sinkholes, and the deposits stalactites (from the roof), stalagmites (from the floor) and pillars.
| Landform | Type / agent |
|---|---|
| Stack, sea arch, cliff, notch | Coastal EROSIONAL (waves) NDA 2018 — a stack is erosional, NOT a depositional feature. |
| Spit, bar, tombolo, beach | Coastal DEPOSITIONAL |
| Stalactite, stalagmite, pillar | Underground water (karst) NDA 2019 — stalactites/stalagmites are deposits of underground water. |
Practice this conceptself-check · 3 quick reps
The same idea in a real exam question:
NDA · Sep 2019 · Q128Easy
Example 5 · Earth's Structure, Landforms and Geological Time · Landforms and Mass Movements
Stalactite, stalagmite and pillars are the depositional landforms of
Stack = erosional
A sea stack is an isolated pillar left after waves erode an arch — it is EROSIONAL. Don't group it with depositional features like spits, bars and tombolos.
Concept 6 of 6: Mass movements
When gravity pulls weathered rock and soil downslope, that is mass movement (mass wasting). It ranges from fast and violent — avalanches of snow and ice, landslides, rockfalls — to slow and quiet creep. Heavy rain and earthquakes are the usual triggers, and clay-rich, steep slopes are the most prone.
Definition
- Avalanche — torrents of snow and ice roaring down a steep mountainside; a mix of falling, rolling, sliding and flowing; hazardous to skiers/mountaineers.
- Landslide — rapid downslope slip; favoured by STEEP slopes, clay-rich soil, and earthquake or heavy-rain triggers (NOT gentle slopes).
- A boulder loosened by rain rolling downhill involves mass wasting + erosion (it is moved AND worn).
- Slower forms: soil creep, solifluction, mudflow, slump.
Worked example
Torrents of snow and ice roar down a steep slope, mixing falling, rolling, sliding and flowing — dangerous to mountaineers. What phenomenon is this?
Practice this conceptself-check · 3 quick reps
The same idea in a real exam question:
NDA · Apr 2022 · Q120Easy
Example 6 · Earth's Structure, Landforms and Geological Time · Landforms and Mass Movements
Consider the following features about a geographical phenomenon:
1. Torrents of snow and ice roaring down a steep mountain side
2. It is hazardous to skiers and mountaineers
3. It involves a mix of falling, rolling, sliding and flowing of materials
Which of the following phenomena can be identified with the above features?
Landslides need STEEP slopes
A trap states landslides happen 'only on gentle slopes during rain'. Wrong — they need STEEP slopes. The true conditions are clay-rich soil and an earthquake/rain trigger.
Summary — formulas & gotchas at a glance
A revision cheat-sheet for the formulas and gotchas above. Click any concept name to jump back to its full explanation.
Reference tables (5)
Mountains and plateaus by origin4 rows
| Mountain type | Origin | Example |
|---|---|---|
| Fold | Compression at convergent boundary | Himalayas, Alps, Andes, Rockies NDA 2023 — Alps, Andes, Rockies are fold mountains; Mt. Fuji is NOT. |
| Block | Faulting (uplifted block) | Sierra Nevada, Black Forest |
| Volcanic | Lava / ash build-up | Mount Fuji, Vesuvius |
| Residual | Erosion remnant | Aravalli |
River (fluvial) landforms3 rows
| Landform | Type | Where |
|---|---|---|
| Gorge / Canyon | Erosional | Upper course |
| Oxbow lake | Erosion + deposition | Middle/lower course NDA 2021 — an oxbow lake results from both erosion and deposition by a river. |
| Delta, levee | Depositional | Lower course / mouth |
Glacial landforms3 rows
| Landform | Type |
|---|---|
| Cirque, U-valley, fjord | Erosional |
| Drumlin | Depositional ('basket-of-eggs') NDA 2021 — basket-of-eggs topography = drumlins. |
| Esker, moraine | Depositional |
Desert (arid / wind) landforms2 rows
| Landform | What it is |
|---|---|
| Barchan | Crescent wind-blown dune; horns point downwind NDA 2024 — barchan is a crescent dune from a one-direction wind (only that claim is fully correct). |
| Playa | Bed of a temporary desert lake (arid landform) NDA 2021 & 2024 — playa = fine-grained ephemeral-lake bed in a bolson; an ARID landform. |
Coastal and karst landforms3 rows
| Landform | Type / agent |
|---|---|
| Stack, sea arch, cliff, notch | Coastal EROSIONAL (waves) NDA 2018 — a stack is erosional, NOT a depositional feature. |
| Spit, bar, tombolo, beach | Coastal DEPOSITIONAL |
| Stalactite, stalagmite, pillar | Underground water (karst) NDA 2019 — stalactites/stalagmites are deposits of underground water. |
Watch out for (3)
- A playa is an ARID landform, not fluvial→ Desert (arid / wind) landforms
- Stack = erosional→ Coastal and karst landforms
- Landslides need STEEP slopes→ Mass movements
Test yourself on Earth's Structure, Landforms and Geological Time
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