Salts and minerals are dissolved into the river water and thus travel in solution. Insoluble materal such as clay floats giving the river water a darker murky appearance as it travels in suspension. larger rocks and stones such as flint travel by saltation where they propagate along the river bed in a bouncing motion. During a storm under high energy these materials can travel by suspension. The largest materials such as boulders travel by rolling. In large storms, they may travel by either saltation or suspension depending on the energy of the river and the weight of the object.