Geomorphic Processes
Class 11 · Geography
4 ideas in Class 11 Geography, explained in plain words, with games and quizzes to practise.
Endogenic and Exogenic Forces
Part of: Forces that shape the surface
Inside heat builds land through folding, uplift, quakes and eruptions; these are endogenic forces. Sun-driven air, water and ice wear land down and fill hollows; these are exogenic forces. The wearing plus filling that levels relief is called gradation. A process is the force on matter, while an agent is the moving carrier like a river or glacier. Nothing moves without slopes and gravity.
Why it matters. Every landform later comes from this tug of war. Mixing up builder and wearer, or process and carrier, confuses all that follows.
Key words
- Endogenic force
- : Inner-earth energy that builds and lifts land
- Exogenic force
- : Sun-driven surface energy that wears and fills land
- Gradation
- : Joint wearing of highs and filling of lows
- Geomorphic agent
- : Moving carrier of matter like rivers or wind
- Gravity pull
- : Downslope force switching on all movement
Try it in two minutes
- Pile sand into a hill and call it built land.
- Pour spoonfuls of water to wear gullies and fill the tray edge.
- Name the pile builder endogenic and the water wearer exogenic.
- Point to water as carrier and slope pull as process force.
Try at home. Watch rain on bare soil and name one wearing spot and one filling spot, plus the carrier.
Weathering and Its Gifts
Part of: Forces that shape the surface
Weathering rots rock where it lies, with almost no movement. Chemical decay uses water, air and heat to dissolve and rust minerals. Physical breakup splits rock by heat swings and pressure release. Living things wedge, burrow and brew acids. Flaked curved sheets called exfoliation show physical work. Rotted beds feed soils, ore riches and plant variety.
Why it matters. Weathering is the quiet starter of soils, farms and mineral wealth. Skipping it makes erosion and soil stories sound like magic.
Key words
- In-situ decay
- : Breakdown of rock at its own spot with no travel
- Chemical decay
- : Rotting of minerals by water, air and heat
- Physical breakup
- : Splitting of rock by heat swings and load release
- Exfoliation
- : Peeling of curved sheets, a result and not a force
- Enrichment
- : Rise in ore share after waste washes away
Try it in two minutes
- Leave one chalk piece dry and soak one in water overnight.
- Compare strength and crumbling next morning.
- Heat a stone and cool it quickly to hear faint ticks.
- Crumble garden soil and name the rotted rock inside.
Try at home. Keep two stones, one wet and one dry, for a week and note which weakens faster.
Mass Movements Down Slopes
Part of: Moving matter and making soil
Mass movement slides rock waste downhill by gravity alone, with no river, wind or ice carrying it. Falls drop freely, slides slip along cracks, flows ooze like wet concrete, and creep inches unseen. Slump turns back as it slips, debris slides do not. Triggers include cut supports, steeper cuts, overload, soaking rains, shakes and bare slopes.
Why it matters. Road and hill safety rests on this idea. Knowing triggers helps read why some slopes fail after rains or cuts.
Key words
- Slump
- : Slip of earth turning backward as it drops
- Debris slide
- : Slip of waste without backward turning
- Rock fall
- : Free drop of blocks from a steep face
- Creep
- : Unseen inching of soil down gentle slopes
- Trigger
- : Cut, soak or shake that frees a slope to move
Try it in two minutes
- Pile damp soil on a tilted tray.
- Tap the tray foot to remove support and watch a slip.
- Spray water and watch the flow turn faster.
- Compare a grassy patch with a bare patch.
Try at home. After rain, spot one slope with fresh scars and list two triggers you can see.
Erosion, Deposition and Soils
Part of: Moving matter and making soil
Erosion grips and hauls rock waste through rivers, groundwater, glaciers, wind and waves. When carriers slow on gentle ground, they drop loads, coarse bits first, filling hollows; this laying is deposition. Soils grow from rotted or carried matter settled by life: tiny plants first, then humus, grasses and trees. Parent rock, relief, climate, life and time steer the build, with climate and life leading actively.
Why it matters. Farms, houses and rivers all rest on this chain. It links rain, slope, soil depth and plant growth in one story.
Key words
- Erosion
- : Gripping and hauling of waste by moving carriers
- Deposition
- : Laying down of loads where carriers slow
- Pedogenesis
- : Slow birth and growth of soil from parent matter
- Humus
- : Dark rotted life remains enriching young soil
- Active factor
- : Climate or life steering soil growth strongly
Try it in two minutes
- Stir sand in a bottle and pour it on a tray.
- Watch fast water grip grains and slow water drop them.
- Note coarse grains halting first, fine silt later.
- Press a sprout into settled silt as first life.
Try at home. Pour muddy water on a slope tray and mark where coarse and fine loads settle.
What your child will practise
- Endogenic and Exogenic Forces: Desert Quick Fire (Quick Fire)
- Erosion, Deposition and Soils: Space Puzzle (Clue Puzzle)
- Erosion, Deposition and Soils: Space Quick Fire (Quick Fire)
- Mass Movements Down Slopes: Ocean Quick Fire (Quick Fire)
- Weathering and Its Gifts: Jungle Puzzle (Clue Puzzle)
- Quiz: Endogenic and Exogenic Forces (8 questions)
- Quiz: Erosion, Deposition and Soils (8 questions)
- Quiz: Mass Movements Down Slopes (8 questions)
- Quiz: Weathering and Its Gifts (8 questions)