Exfoliation and sheeting occurs because water combines with minerals and increases their size, thereby causing surrounding minerals to expand. water freezes in joints and expands. overlying rock is removed, thereby allowing the underlying rock mass to expand and fracture. O evaporated water leaves behind previously dissolved mineral to form crystals, which accumulate and grow over time, exerting pressure on the rock. rock minerals react with carbonic acids in rain, causing weathering to occur. When rock is dissolved or altered by of water and with chemical alterations to the rock, the process in operation is physical weathering. chemical weathering. mass movement. scarification. O biological weathering.