Page 169 - Primary Five Science

(iii) Gully Erosion: This is the third stage of sheet erosion. With

further erosion of the soil, the rills may deepen and become

enlarged, and are ultimately turned into gullies. The main

cause of gully erosion is the removal of vegetation, particularly

of trees with their widespread binding roots. Gullies cut up ag-

ricultural land and the entire area may be turned into a bad
land topography. Gully erosion is also responsible for the for-

mation of ravines.

2. Wind erosion

Wind is a powerful agent of erosion in arid and semi-arid

lands with little rainfall. Wind can lift the valuable top soil

from one area and deposits in another area. The wind erosion

is very dangerous type of erosion because due to wind most of

the deserts of the world are expanding.