Ch-6: Landforms and Their Evolution

Earth ki surface par small to medium tracts ko **Landforms** kehte hain. Jab kayi landforms milte hain, toh wo ek **Landscape** banate hain. Har landform ki apni history hoti hai jo teen stages se guzarti hai: **Youth, Mature aur Old age**.

1. Running Water (Behta Pani)

Humid regions mein running water sabse important agent hai.

• Erosional Forms: Valleys (V-shaped), Gorges (steep sides), aur Canyons (step-like slopes). Potholes aur Plunge pools waterfalls ke niche bante hain.
• Depositional Forms: Alluvial Fans tab bante hain jab mountain streams plains mein aati hain. Rivers jab samundar mein milti hain toh Deltas banati hain. Floodplains, Natural Levees, aur Point Bars bhi river deposition se bante hain.

2. Groundwater (Karst Topography)

Groundwater limestone aur dolomite rocks mein **Solution** aur **Precipitation** se landforms banata hai. Isse **Karst Topography** kehte hain.

• Erosional: Sinkholes (funnel shaped), Uvalas (valley sinks), aur Lapies (irregular ridges). Guphaein (Caves) bhi isi se banti hain.
• Depositional: Stalactites (gupha ki chhat se latakte hue), Stalagmites (farsh se upar uthte hue), aur jab dono mil jayein toh Pillars bante hain.

3. Glaciers (Barf ki Nadi)

Glaciers gravity ki wajah se dhire move karte hain.

• Erosional: Cirques (head walls), Horns (Everest ek horn hai), aur U-shaped Valleys.
• Depositional: Moraines (debris ridges), Eskers (sinuous ridges), aur Drumlins (smooth oval ridges).

4. Waves and Currents (Coastal)

• Erosional: Cliffs, Wave-cut platforms, Caves, aur Stacks (isolated rocks).
• Depositional: Beaches, Dunes, Bars, Spits, aur Lagoons. West coast erosional hai, jabki East coast depositional.

5. Winds (Deserts)

Hot deserts mein wind aur torrential rain kaam karte hain.

• Erosional: Pediments, Pediplains (low featureless plains), Playas (shallow lakes), aur Mushroom Rocks.
• Depositional (Sand Dunes): Barchans (crescent shaped), Seif (one wing), Parabolic, Longitudinal, aur Transverse dunes.

--- EXERCISE SOLUTIONS ---

1. MCQs:

• (i) Downward cutting dominant stage? → (a) Youth stage
• (ii) Deep valley with step-like slopes? → (d) Canyon
• (iii) Chemical weathering dominant region? → (b) Limestone region
• (iv) Term 'Lapies' definition? → (d) Irregular surface with sharp pinnacles/grooves
• (v) Deep long basin with steep concave walls? → (a) Cirque

2. Short Answers (30 Words):

(iii) **Limestone mein groundwater kyun common hai?** Kyunki yahan rocks permeable aur jointed hoti hain, jisse pani niche solution banata hai.

(v) **Wind in deserts?** Wind fine materials ko move karti hai, par sheet floods bhi erosional features banate hain.

Project Work:

Apne area ke landforms, materials aur processes ki pehchan karein.

[River Stages]

Youth: V-Shape 📉
Mature: Floodplain 🌊
Old: Peneplain 🗺️

[Karst Cave]

Stalactite (Ceiling) ⬇️
Stalagmite (Floor) ⬆️
Pillar (Joined) 🏛️

[Glacier]

Cirque 🥣
U-Shaped Valley 📦
Drumlins (Egg-like) 🥚

[Sand Dunes]

Barchan: 🌙
Seif: 🗡️
Transverse: 📏

🌍🌋💨