Which of the following is not a fast type of mass movement?

Correct option is D

Solifluction is a slow type of mass movement that occurs in regions with permafrost or seasonal freeze-thaw cycles. It involves the gradual downslope movement of water-saturated soil due to gravity. Since it progresses slowly over time, it does not fall into the category of fast mass movements like rockfalls, mudflows, or slumps.

Information Booster:

1. Solifluction is common in cold climates where the ground remains frozen for much of the year.
2. The top layer of soil moves downslope when thawed, while the frozen lower layer prevents drainage.
3. It leads to the formation of lobate (tongue-shaped) or sheet-like structures on slopes.
4. It is different from landslides or mudflows, which are rapid.
5. Solifluction occurs in tundra regions and high-altitude areas.
6. Human activities like deforestation can accelerate this process by reducing soil stability.

Additional Knowledge:

(a) Rock Fall: This is a fast mass movement where rocks or debris fall freely from a cliff or steep slope due to gravity. It occurs suddenly and is one of the fastest types of mass movement.

(b) Mud Flow: A very rapid flow of water-saturated soil and debris down a slope. It is common in volcanic eruptions (lahars) and heavy rainfall areas.

(c) Bed Rock Slump: A moderately fast type of mass movement where a section of bedrock or soil moves downslope along a curved surface, often due to water saturation and weak rock layers.