Saccharine limestone, 19, 32 Saliferous system, 47 Saline properties of the ocean, how obtained, 104 Salt beds-- where found, 118 how formed, 119 Sandstone, 19 Schorl, 16 Scoriæ, 17, 133 Sediment-- amount of in rivers, 107 deposition of, 113 sorted by rivers, 112 Selenite, 16 Serpentine, 15 a primary rock, 25 Shale, 20 Siberia, remains of elephants in, 89 Sigillaria, 45 Silicium, 12 Sinking of wharves, towns, &c., 79 Silurian system, 34 tabular arrangement of, 34 divisions of, 35 fossils of, 36 geographical range, 38 Slaty structure-- in the gold washings of Chili, 98 produced by electric currents, 98 Slope of mountains, 73 Soapstone, 15 Sodium, 13 Solidification of rocks, 68, 119 Soluble materials of rocks, 103 Solution of mineral substances-- promoted by heat, 104 promoted by an alkali, 104 promoted by carbonic acid, 105 Sources of the sedimentary materials, 103 Sources of the sediment of rivers, 97 Species-- disappearance of, 62 causes of the disappearance of, 62 Springs, 92 Stability of continents only apparent, 145 Statuary marble, 19 Stigmaria, 44 Strata-- horizontal, 70, 115 permeable and impermeable, 92