Maharashtra Board Class 11 Geography Notes Chapter 3 Agents of Erosion

By going through these Maharashtra State Board Class 11 Geography Notes Chapter 3 Agents of Erosion students can recall all the concepts quickly.

Maharashtra State Board Class 11 Geography Notes Chapter 3 Agents of Erosion

Agents of Erosion:

1. Running Water(River)
2. Sea Waves
3. Wind
4. Glaciers
5. Ground Water

→ Agents of erosion cause various processes when they pick up, move and deposit rock particles. These processes lead to erosional and depositional landforms.

Processes of Erosion:

River-

• Attrition
• Solution
• Downcutting
• Drilling
• Headward erosion
• Lateral erosion

Sea Waves-

• Abrasion
• Attrition
• Solution
• Lateral erosion

Wind-

• Abrasion
• Attrition
• Deflation

Glacier-

• Plucking
• Abrasion
• Downcutting
• Headward erosion
• Lateral erosion

Ground Water-
Solution

Processes of Transportation :

• Traction : The material acquired by the agents is transported by rolling, pushing and dragging along the surface.
• Saltation : Often the rock materials move forward by leaps and bounds through this process.
• Suspension : Fine light material is carried along with water or air in the upper layer.
• Solution : The material is carried in water in a dissolved state.

Processes of Transportation :

River-

• Traction
• Saltation
• Suspension
• Solution

Sea Waves-

• Traction
• Saltation
• Suspension
• Solution

Wind-

• Traction
• Saltation
• Suspension

Glacier-
Traction

Ground Water-
Solution

Processes of Erosion :

• Plucking : The process by which moving ice exerts pressure on majority portion of rocks on bed or along the bank.
• Abrasion : It involves the scratching and polishing of the surface or bedrock by the particles which are moving onto it.
• Attrition: It is when rocks and pebbles bump into each other and break up into smaller fragments.
• Solution : It is when certain types of rocks get eroded as a result of acids in the sea or river water.
• Deflation : The particles which are loosened on the surface are blown away by the wind.
• Drilling : Bedload moves along the running water. As and when this flow encounters an obstacle due to relief on the bed or joints in the bed, the flow tends to develop a circular pattern. This leads to development of a whirl.
• Downcutting : Also called downward erosion is a process of hydraulic action that deepens the channel of a stream or valley by removing material from the stream’s bed or the valley’s floor.
• Headward erosion : It is the backward erosion by river in the source region.
• Lateral erosion : It is the erosion that occurs on the sides of valleys of a river or glacier.

Agents of erosion and landforms :
Factor affecting formation of landforms – climate, type of rocks, intensity of erosion, slope of land and obstacles.

River as an Agent of Erosion:

1. Erosional Features
2. Depositional Features

1. Erosional Features

• Gorges and Canyons
• V-shaped valley
• Cliffs
• Waterfalls
• Rapids
• Potholes

2. Depositional Features

• Alluvial fans
• Meanders
• Oxbow lakes
• Flood plains
• Natural levees
• Islands
• Deltas
• Estuaries

Sea Water as an Agent of Erosion:

Erosional Features-

• Sea cliffs
• Sea caves
• Sea arch
• Sea stack
• Wave cut platforms

Depositional Features-

• Sea beach
• Lagoon
• Headlands
• Sand spits

Conditions necessary for wind erosion :

• Aridity – In such areas, rate of evaporation is greater than rate of precipitation.
• Sparse vegetation cores or absence of trees.
• Presence of dry loose materials at the surface.
• A wind velocity high enough to pick up and move sediments.

Wind as an agent of Erosion:

1. Erosional Features
2. Depositional Feature

1. Erosional Features:

• Deflation Hallows
• Ventifacts
• Mushroom Rocks
• Yardangs

2. Depositional Feature

• Loess
• Barchans
• Sand Dunes

Karst topography needs three important factors to develop:

1. Carbon dioxide
2. Active movement of underground water
3. Joints

Work of Ground Water:

1. Erosional Features
2. Depositional Features

1. Erosional Features

• Sink Holes
• Caves

2. Depositional Features:

• Stalactite
• Stalagmite
• Columnor Pillars

Work of Glaciers:

1. Erosional Features
2. De positional Features

1. Erosional Features:

• Roche mountonnees
• Cirque
• Arete
• Horn, Matterhorn
• U-Shaped valley, hanging valley

2. De positional Features:

• Drumlin
• Eskers
• Erratic rock