The correct answer is - landslide.
The landslides are mass movements that involve rocks, soil, debris, moving as a single unit. The movement is always from a higher part towards a lower part, from a hill or mountain towards a valley.
This mass movement appears either after heavy rainfall or earthquakes. When there's heavy rainfall, the water over-saturates the soil, thus it starts to move downwards, taking with it everything on it, including the rocks and the debris, as well as plants. The earthquakes, on the other hand, make the ground move with their vibrations, and once it can not withstand the pressure, it moves downwards with everything on it.
