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
Intuition
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
Try it yourself
Which is NOT a fold mountain: Mt. Fuji, Alps, Andes, Rockies?
Practice — Level 1 (3 reps)
Quick reps to lock in the method. Try each, then check.
- 1.The Himalayas are which mountain type?
- 2.Mount Fuji is which mountain type?
- 3.The Aravalli range is which type?
From the bank · past-year question
Which one of the following is NOT an example of Fold Mountain?
[Q123 · Sep · 2023]
Concept 2 of 6
River (fluvial) landforms
Intuition
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
Try it yourself
A deep valley with steep, step-like sides is called a?
Practice — Level 1 (3 reps)
Quick reps to lock in the method. Try each, then check.
- 1.A cut-off meander loop becomes a?
- 2.Paradeep Port lies on the delta of which river?
- 3.The uplands of a delta region are called?
From the bank · past-year question
Which one of the following features is the result of erosion and deposition work of a river?
[Q85 · Sep · 2021]
Concept 3 of 6
Glacial landforms
Intuition
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
Try it yourself
'Basket-of-eggs' topography is made of which glacial landform?
Practice — Level 1 (2 reps)
Quick reps to lock in the method. Try each, then check.
- 1.An armchair-shaped glacial hollow is a?
- 2.Egg-shaped depositional mounds of till are?
From the bank · past-year question
Basket-of-eggs topography is related to
[Q119 · Apr · 2021]
Concept 4 of 6
Desert (arid / wind) landforms
Intuition
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
Try it yourself
The fine-grained bed of an ephemeral desert lake is called a?
Practice — Level 1 (2 reps)
Quick reps to lock in the method. Try each, then check.
- 1.A crescent-shaped sand dune is a?
- 2.A playa belongs to which landform category?
From the bank · past-year question
Fine-grained bed of ephemeral lake in a desert is also known as
[Q54 · Sep · 2021]
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
Intuition
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
Try it yourself
Which is NOT a coastal DEPOSITIONAL feature: tombolo, sand bar, stack, spit?
Practice — Level 1 (3 reps)
Quick reps to lock in the method. Try each, then check.
- 1.Stalactites and stalagmites are deposited by which agent?
- 2.Is a sea stack erosional or depositional?
- 3.Name one coastal depositional feature.
From the bank · past-year question
Stalactite, stalagmite and pillars are the depositional landforms of
[Q128 · Sep · 2019]
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
Intuition
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?
- Snow + ice + steep slope + mixed motion is the key combination.
- A landslide/rockslide is rock, not snow; an earthflow is slow mud.
- Fast-moving snow and ice down a mountainside is an avalanche.
Answer:An avalanche.
Practice this conceptself-check · 3 quick reps
Try it yourself
Landslides: (1) occur only on gentle slopes; (2) occur in clay-rich soil; (3) are triggered by earthquakes. Which are correct?
Practice — Level 1 (3 reps)
Quick reps to lock in the method. Try each, then check.
- 1.Fast-moving snow and ice down a steep slope is a?
- 2.Do landslides occur on gentle or steep slopes?
- 3.Name one trigger of landslides.
From the bank · past-year question
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?
[Q120 · Apr · 2022]
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
Mastery check — 5 interleaved questions
Try each one before clicking. Questions are interleaved across the concepts above, not grouped — interleaving sharpens transfer.
A deep valley characterized by steep step-like slope is known as
[Q129 · Sep · 2019]
The lowest part of most bolsons is occupied by a landform called playa. Which category of landform formation does it represent ?
[Q83 · Sep · 2024]
Which one of the following is NOT a coastal depositional feature?
[Q98 · Apr · 2018]
While travelling to a hilly region, you notice a massive boulder, which was loosened by heavy rains and moved downhill. This has resulted due to which of the following processes?
1. Mass wasting
2. Erosion
3. Weathering
Select the correct answer using the code given below.
[Q118 · Apr · 2022]
Which one of the following is known as uplands of delta region?
[Q74 · Sep · 2018]
Drill every past-year question on this subtopic
15 questions from the bank — paginated, with cart and Word-export support.