Detritus (pronunciation: /dɪˈtraɪtəs/; adjective detrital /dɪˈtraɪtəl/) is particles of rock derived from pre-existing rock through processes of weathering and erosion. A fragment of detritus is called a clast. Detrital particles can consist of lithic fragments (particles of recognisable rock), or of monomineralic fragments (mineral grains). Particles may be transported to riverbeds, lakes, or oceans, forming sedimentary successions. Diagenetic processes can transform these sediments into rock through cementation and lithification, forming sedimentary rocks such as sandstone. These rocks can then in turn again be weathered and eroded to form a second generation of sediment.