Weathering is the dissemination, destruction or breaking of the rock to finer particles. Weathering occur by many means, it can be either chemical, organic or mechanical.
Chemical weathering occurs by the ion exchange method, dissolution of some particles which breaks the bond and the rock is thus weathered. The rock is dissolved when it is acid rain and the rock weathers. the best example in understanding chemical weathering is water dissolving limestone producing Karst topography. This help in the building of sedimentary rocks by erosion. Erosional means are wind, gravity, ice and water. When sediments are eroded it deposits at some other place, builds sedimentary rocks
Organic as the name indicates is done by organisms. Plant roots break rock when they move into the rock and so the weathering process occurs.Rock is first weakened by penetrating forces of roots and thus split into smaller and smaller pieces. These are then eroded.
Mechanical weathering is the physical breaking of a rock by means of force. The best example of the mechanical weathering is the permafrost. The water enters the pores and joints of a rock and when it freezes at low temperature areas. As the property of water at freezing is expansion so the water in rocks expands which widens the spaces and after some time disintegrated.
The deposition of these sediments occur when wind, water or ice slows in speed and have no capacity to blow away the particles, it deposits.