Icebergs-- how formed, 124 earthy materials in, 125 motion of, 125 size and number of, 125 effect in distributing drift, 126 grooving the surface, 126 Iceland spar, 19 Iceland, volcanic eruption in, 26 Ichthyosaurus, 50 Igneous causes, 127 Iguanodon, 51 Inclined position of strata produced by upheaval, 70, 140 Increase of temperature below the surface, 127 Iron, 12

J.

Jasper, 14 Jorullo, 131

K.

Kilauea, 26, 142

L.

Lakes, filling up of, 76, 113 Lava, 17, 25, 137 varieties of, 25 tertiary, 27 elastic vapors contained in, 130, 132 great quant.i.ty of modern, 26 Lead-bearing strata, 35, 40 Lepidodendron, 46 Lias, 19, 49 Limestone, 15, 19 as a primary rock, 25 metalliferous, 40 Local changes of climate, 90

M.

Magnesian limestone, 19, 47 Magnesium, 13 Mammoth, 56 Man-- recently created, 59 as an agent in producing geological changes, 101 impressions of the feet of, 59 skeleton of from Guadaloupe, 59 Manganese, 12 Marine currents, 108 Marine currents, cause of, 109 abrading power of, 111 Marl, 19 Mastodon, 55 Megatherium, 55 Metamorphic changes, 67 Metamorphic rocks, 30 amount of, 67 origin of, 134 order of superposition, 31 upper limit variable, 13 localities of, 32 Metallic ores, 92 Mica, 14 slate, 18, 31 Millstone grit, 40 fossils of, 41 becomes coal measures, 42 Mineral-- definition of, 13 Mineral veins, 69 formation of, 100 Modern formation, 57 why but little known, 57 fossils, 57 Moisture of the atmosphere a disintegrating agent, 96 Monte Nuovo, 26 Mount Loa, eruption of, 26

N.

Neocomian system, 52 New red sandstone, 47 fossils of, 48 ores of, 47 geographical range of, 49 Niagara Falls, how preserved, 106 Nitrogen, 11 Nummulite rock, 54

O.

Oceanic mountains, 75 Ocean level, nearly permanent, 74 Old red sandstone, 38 fossils of, 39 extent of, 39 Oolite, 19 Oolitic structure, 49 Oolite system, 49 calcareous, 49 fossils of, 50 localities of, 51 Opal, 14 Organic causes, 101 Orthoceras, 36, 40 Outcrop, 71 Oxide of iron, 16 Oxygen, 11

P.

Paleotherium, 55 Papandayang, 95, 142 Permian system, 47 Plesiosaurus, 51 Porphyritic structure, 17 Pota.s.sium, 12 Primary limestone, 19 Pterodactyle, 51 Pumice-stone, 17 Pyroxene, 15

Q.

Quartz, 14 rock, 32

R.

Raindrops, impressions of, 48 Raised beaches, 76 Ravine, 69 Recent elevation in Europe, 79 Recent formation, 57 Ripple marks, 48 Rivers-- beds of, raised, 113 continued into the sea, 112 abrading action of, 105 abrading action of promoted by foreign substances, 106 Rock crystal, 14 Rock salt, 16, 118 Rocks, denned, 16 Rose quartz, 14

S.

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 Scoriae, 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 irregular, how produced, 115 Striated surfaces, 87 Submerged forests, 79 Subsidence of land, 79, 145 Subsidence of land in Greenland, 82 Subsidence and elevation in the Pacific, 80 Sulphate of lime, 15 Sulphur, 12 Sun-cracks, 48 Sunken areas, 142 Syenite, 17 Synclinal axes, 72

T.

Taconic system, 32 Talc, 15 Talcose slate, 20, 32 Temperature at great depths, 127 Temple of Jupiter Serapis, 83 Tertiary system, 53 age, how determined, 53 fossils, 54 divisions of, 53 geographical range, 56 Tilestones of the old red sandstone, 38 Trachyte, 18 Tracks in new red sandstone, 49 Transportation of sediment, 111 Trappean rocks, 17 localities of, 29 Tremolite, 15 Trias, 47 Trilobite, 37, 40

V.

Valley, 69 of elevation, 71, 75 of subsidence, 72

Valley of denudation, 87 Vein of segregation, 69 Verd-antique marble, 15 Volcanic rocks, 17, 25 of different ages, 26 in what states ejected, 25 Volcanic mountains, dimensions, 26 Volcanic activity-- regions of, 129 water essential to, 130 Volcanic cones-- formation of, 131 lateral, 132 Volcanic cinders, scoriae, gla.s.s, 132 Volcanic action, effects of, 133 Volcanic origin-- of trappean rocks, 138 of granitic rocks, 138 Volcanoes-- number, 26 linear arrangement of, 131 near the sea, 129 new, 131 of the tertiary period, long active, 28

W.

Watt on fusion of basalt, 100 Waves, action of, 107 Wealden, 49 Wind a geological agent, 96

Z.

Zechstein, 47

QUESTIONS

TO

ELEMENTS OF GEOLOGY

QUESTIONS.

CHAPTER I.

SECTION I.

How many elementary substances are known?