Describe how lichens and big trees influence the formation of soil.

(N/A) $(i)$ Lichens grow on the surface of rocks and release certain chemicals that cause the rock surface to powder down,creating a thin layer of soil.
$(ii)$ Mosses then grow on this surface,which further breaks down the rock material.
$(iii)$ The roots of big trees grow into the crevices of rocks,creating cracks and widening them over time,which eventually leads to the formation of soil.