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The process of levelling up of lands by means of natural agents is____________.

Gradation is the process of levelling up and formation of land surface by the operation of natural agents like air, water, glaciers or sea waves. The action of these agents results in the formation of various geographical features and structures with the passage of time. It is a highly time-consuming process and can result in the formation of sea cliffs, canyons, waterfalls and various other landforms. It occurs because of the combined action of erosion, transportation and deposition.