Exogenous Processes and Associated Landforms

Static; Mobile

Step 1: Weathering is defined as the breaking of rocks by static agents of weather. Step 2: The key word is 'static' — in weathering, the rock material does not move (no transportation occurs). Step 3: The disintegrated material only falls down due to gravity but is not carried away. Step 4: Erosion, on the other hand, is a mobile process — it involves the picking up and transportation of weathered rock material from one place to another. Step 5: This is an important distinction: weathering breaks rocks IN PLACE, while erosion moves the broken material.

Hot and dry desert areas

Step 1: Insolation weathering is caused by rapid changes in temperature — rocks expand when heated and contract when cooled. Step 2: For this to be effective, there must be extreme temperature changes between day and night. Step 3: Hot and dry desert areas experience very high temperatures during the day and very cold temperatures at night. Step 4: This rapid alternation of expansion and contraction creates cracks in rocks, leading to block disintegration or granular disintegration. Step 5: Tropical rainforests have humid conditions more suited to chemical weathering. Polar regions are too con

Exfoliation

Step 1: Some rocks are poor conductors of heat. Step 2: As a result, when temperature changes, the outer layers expand or contract more than the inner layers. Step 3: This unequal expansion and contraction causes the outer layers to peel off from the rock in curved, concentric shells. Step 4: This process is called exfoliation, and it looks exactly like peeling layers off an onion. Step 5: Block disintegration is when rocks split into blocks, granular disintegration is when rocks break into small grains, and freeze-thaw is related to frost action — all are different types of physical weatherin

9%

Step 1: Frost action (freeze-thaw) is an important type of physical weathering in cold regions. Step 2: Water seeps into the cracks and joints of rocks during the day. Step 3: At night, when temperature drops below 0°C, this water freezes. Step 4: When water turns to ice, its volume increases by about 9% — on average, 9 cubic centimetres of water becomes 10 cubic centimetres of ice. Step 5: This expansion creates a bursting pressure of about 150 kg per square centimetre, which is enough to crack and rupture rocks. So 9% is the correct answer.