568. But the cavities, besides raising mountain chains, could just as well depress or allow them to sink in, and thus produce valleys. By these means the seas have probably been formed. Like the seas so also have the inland seas or lakes originated. 569. Lastly, a similar origin must be ascribed to the world-sea or ocean. Many earthquakes arose, with all their concomitant phenomena, by partial and sudden falling in of the deep descending cavities of the earth. Frequently that which fell in was again driven out by the expansive force of the suddenly compressed air. 2. _Organs of the Planet._ 570. The principal mass or body of the planet is formed by the earths proper, as being the typical or genuine representatives of the earth-element. The other classes, as the metallic minerals or ores, the Inflammables, and salts, are to be regarded only as viscera of this body. If we take a circumspective glance at the planet, we cannot fail to recognize this remarkable relation, that it is properly the elemental families only of the earths that form the mountain masses, while the other families are only scattered within them, like the glands in an animal body. Let us again place the Families in tabular contrast with each other. SILICIOUS, ARGILLACEOUS, TALCOSE and CALCAREOUS-EARTHS. A. Earth-silices. Earth-clays. Earth-talcs. Earth-calces. Fam. 1. Quartz. 1. Felspar. 1. Mica. 1. Lapis-lazuli. 2. Zircon. 2. Sapphire. 2. Sappharine. 2. Mesotype. 3. Emerald. 3. Ruby. 3. Talc. 3. Stellite. 4. Leucite. 4. Epidote. 4. Angite. 4. Tabular-spar. 5. Topaz. 5. Schorl. 5. Hornblende. 5. Boracite. 6. Diamond. 6. Azurite. 6. Asbestus. 6. Phosphorite. 7. Garnet. 7. Harmotone. 7. Olivine. 7. Titanite. B. Water-silices. Water-clays. Water-talcs. Water-calces. 8. Hornstone. 8. Clay-slate. 8. Serpentine. 8. Hydrophyllite. C. Air-silices. Air-clays. Air-talcs. Air-calces. 9. Tripoli. 9. Clay-stone. 9. Lithomarge. 9. Gypsum. D. Fire-silices. Fire-clays. Fire-talcs. Fire-calces. 10. Obsidian. 10. Lava. 10. Basalt. 10. Limestone. 571. Now we here observe that only Quartz, Hornstone, Tripoli and Obsidian, occur as mineral aggregates in large masses, while all the others are only rare precious stones. Among the Clays, only Felspar, Clay-Slate, Hornstone and Lava. Among the Talcs, only Mica, Serpentine, Lithomarge, and Basalt. Among the Calcareous-earths, which incline towards the nature of salts, all the first families are of rare occurrence, and the latter only appear as mineral masses. This regularity speaks moreover retrospectively in favour of the correctness of the classification. The families have thus the same import or value in Geology as in Oryctognosy. A.--_EARTHS_.