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,
Name of Croatia the derivation of Proto-Slavic *xъrvatъ from the Old Persian "xaraxwat-", attested by the Old Iranian toponym "Harahvait-", the native name of Arachosia. "Arachosia" is the Latinized form of Ancient Greek Ἀραχωσία ("Arachosíā"); in Old Persian inscriptions, the region is referred to as "" (). In Indo-Iranian it actually means "one that pours into ponds", which derives from the name of the Sarasvati River of Rigveda. However, although the somewhat suggestive similarity, the connection to the name of Arachosia is etymologically incorrect. The first etymological thesis about the name of the Croats stems from Constantine Porphyrogennetos (tenth century), who connected the