Volcano were proposed for volcano behavior before the modern understanding of the Earth's mantle structure as a semisolid material was developed. For decades after awareness that compression and radioactive materials may be heat sources, their contributions were specifically discounted. Volcanic action was often attributed to chemical reactions and a thin layer of molten rock near the surface. Volcano A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. Earth's volcanoes occur because its crust is broken into 17 major,
Liquid chalk Liquid chalk The term liquid chalk refers to several different kinds of chalk: Despite the term, some forms of "liquid chalk" contain no actual chalk. Liquid chalk can be a variation of normal chalk (see: magnesium carbonate) used to improve grip for sports, such as rock climbing, weight lifting, or gymnastics. Rock climbers use liquid chalk to prevent their hands from sweating. It may be used by climbers in situations where powdered chalk is restricted. It is preferred by athletes because it remains effective longer and leaves less residue on rocks and equipment. Liquid chalk for rock climbers is made