Q. Which of the following is/are rapid mass movement of rocks or debris?
1. Earthflow
2. Creep
3. Avalanche
4. Landslide
Select the correct answer using the codes given below:

[A] 1, 2 and 3 only

[B] 2, 3 and 4 only

[C] 1, 3 and 4 only

[D] 1, 2, 3 and 4

Answer: C

Mass Movements transfer the mass of rock debris down the slopes under the direct influence of gravity. That means, air, water or ice does not carry debris with them from place to place but on the other hand the debris may carry with it air, water or ice.  

  • The movements of mass may range from slow to rapid, affecting shallow to deep columns of materials and include creep, flow, slide and fall. 
  • Creep can occur on moderately steep and soil covered slopes. Movement of materials is extremely slow and imperceptible except through extended observation. Material involved can be soil or rock debris. 
  • Landslides are relatively rapid and perceptible movements. The materials involved are relatively dry. The size and shape of the detached mass depends on the nature of discontinuities in the rock, the degree of weathering and the steepness of the slope. 
  • Movement of water saturated clayey or silty earth materials down low-angle terraces or hillsides is known as Earthflow. 
  • Avalanche is more characteristic of humid regions with or without vegetation cover and occurs in narrow tracks on steep slopes. Debris avalanche is similar to snow avalanche. 

Source: NCERT – XI Fundamentals of Physical Geography