The coarsest sediments are those produced by land sliding and glaciation which maytransport fragments of rock so large that an examination at close range may fail torecognize that they have been displaced. More commonly, rock fragments found beloweroding cliffs may be many tones in weight. Such very large fragments may befurther eroded during river transportation to gravel and boulder size. These fragmentsare recognizably rock but, as they disintegrate to yet smaller and sand-size grains, thegrains tend to be largely of single minerals. The type of mineral of which they are composed will depend upon the source rock and the degree of abrasion suffered during transportation.