Clay slate, [466].
Cleavage, mineral, [27], [450];
rock, [44].
Clefts, volcanic, in Iceland, [99].
Cliffs, notched, [233].
Climatic conditions, in relation to mountain sculpture, [443].
Clinometer, [48].
Cloudbursts, in deserts, [201], [212].
Cloud zones, [268], [269], [294].
Coals, [466].