Question

What are the types of mass movements?
A. Rapid on steeper slopes
B. Slower on gentle slopes
C. Both A and B
D. None of these

Answer 1

Hint: Mass movements happen when weathered particles move down under the influence of gravity alone. Broadly speaking there are two ways a mass movement can occur.

Complete Answer:Mass movement is also known as mass wasting and it is the movement of large masses of bodies of soil, mud, bedrock, etc. This occurs usually along mountains or hills which have steep sides. The main reason behind mass movement is the pull of gravity.

In landslides, avalanches, mud slides, etc we can see the slipping of large amounts of rock and soil. Mass movement occurs at different speeds. They may vary from slow to very high speeds. On steep slopes mass movement occurs rapidly whereas on gentle slopes they are much slower.

We can classify mass movements into four different kinds :-

Rockfall - In this rocks or bits of rock fall off a cliff face.

Mudflow - In this soil filled with water (saturated soil) flows down a slope.

Landslides - In this there is sliding of large blocks of rock downhill.

Rotational Slip - In this soil filled with water slumps down a curved surface.

Creep is the slowest and the least noticeable type of mass movement or wasting. Creep involves the entire hillside and in it rock or soil material moves over a period of several years. Rockfall is the fastest type of mass movement or wasting.

So, the correct answer is option C.

Note: Mass movement is a geomorphic process and it happens because of the pull of gravity. However there can be various triggers - earthquakes, increased overburden from structures, increased soil moisture reduction of roots holding the soil to the bedrock, etc.