Lichens are the effective agencies on disintegration and weathering processes of rocks. These effects mainly depend on the kind of rocks and site characteristics. The steps of the disintegration process is; 1) penetration hyphae of lichens into the rocks 2) expansion and contraction of lichen thallus 3) freezing and thaving of lichen thallus 4) incorporation of mineral fragments into lichen thallus. Weathering process also goes on together with all these disintegration effects, and include two steps. First step is COı emission by respiration of licherıs, lichen acids and other lichen compounds change the rock structure. Second step is; lichens constitute new compounds on their own bodies or contact points on rock accompanied by changed structure, and lichens use the minerals of rock in this step.