Which of these is not a cause of desertification in the region?

'Climatic variations' and 'Human activities' can be regarded as the two main causes of desertification. removal of the natural vegetation cover（by taking too much fuel wood）, agricultural activities in the vulnerable ecosystems of arid and semi-arid areas, which are thus strained beyond their capacity.

Answermost of the time it would be ground into fine sediment,and sometimes they are carried away from the original location;