4. Exogenetic Processes Part- II
Complete solutions to the Exercise. Maharashtra State Board (Balbharati), Grade 9 Geography.
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Exercise
- (1) The temperature range helps the wind in its work.
- (2) River's work is more prominent than other agents of erosion in desert regions.
- (3) The work of groundwater is effective in the area with soft rocks.
- ✓ (4) The work of wind is not limited like river, glacier or the sea waves and takes place everywhere.
Correct Statement: (4) The work of wind is not limited like river, glacier or the sea waves and takes place everywhere.
(1) The ice on the lateral side of the glacier moves faster than the ice at the base.
Incorrect.
Corrected statement: The ice in the middle of the glacier moves faster than the ice on the lateral sides and the base due to lesser friction.
(2) The depositional work by rivers happens because of gentle slope, reduced speed and transported sediments.
Correct statement.
(3) A river flows at a faster speed than the glacier.
Correct statement.
(4) The speed of the glacier is more on both the banks than in the middle.
Incorrect.
Corrected statement: The speed of the glacier is less on both the banks than in the middle due to the friction created by the banks.
- (1) Deposition - V-shaped valley
- (2) Transport - Ripple Marks
- (3) Erosion - Mushroom Rocks
Answer: The wrong pairs are (1) Deposition - V-shaped valley (as V-shaped valleys are formed by the erosional work of rivers) and (2) Transport - Ripple Marks (as ripple marks are formed by the depositional work of wind).
Mushroom Rocks are formed by the erosional work of wind, so pair (3) is correct.
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This is a diagram-based activity. Please refer to the corresponding textbook diagrams to identify the specific landforms (e.g., V-shaped valley, gorge, sand dunes, sea arch, etc.) shown in your textbook.
Given landforms: waterfall, delta, cirque, arête, barchans, moraine, pothole, mushroom rock, sinkholes, beach, pillars, lagoons.
| Agent | Landforms |
|---|---|
| Rivers | Waterfall, Delta, Pothole |
| Wind | Barchans, Mushroom rock |
| Glacier | Cirque, Arête, Moraine |
| Sea Waves | Beach, Lagoons, Pillars (Sea stacks) |
| Groundwater | Sinkholes |
(1) List the landforms that are a result of the erosional work of the rivers.
The fast flow of river water, along with sand particles and pebbles, erodes the riverbed and banks. The landforms formed as a result of the erosional work of rivers are:
- Gorges (Canyons)
- V-shaped valleys
- Waterfalls
- Potholes
(2) Which agent is responsible for formation of stalactites and stalagmites and where are they formed?
The agent responsible for the formation of stalactites and stalagmites is groundwater.
Where they are formed: They are formed in limestone caves. When groundwater containing dissolved minerals (like calcium carbonate) evaporates, or when the volume of soluble minerals exceeds the solubility limit, the dissolved materials start depositing from the roof of the cave (forming stalactites) and on the floor of the cave (forming stalagmites).
(3) List the landforms that are produced by the depositional work of the sea waves.
Eroded materials accumulate at the seabed and are constantly moved toward and away from the coast by tides, causing them to become fine through attrition. They are deposited where the wave effect is weak. Landforms produced by the depositional work of sea waves include:
- Beaches
- Sand bars
- Lagoons
(4) Name the types of moraines.
The sediments carried and deposited by a glacier are called moraines. Depending on the location of the deposits, moraines are divided into four types:
- Ground moraines: Material deposited at the base of a glacier.
- Lateral moraines: Material deposited along the sides (banks) of a glacier.
- Medial moraines: Material deposited in the center where two glaciers meet.
- Terminal moraines: Material deposited at the end (snout) of a glacier where the ice melts.
The field observation and collage-making activities are to be done practically under your teacher's guidance.