INDEX. 
- Hornbeam, fossil, 839, 877 
Hornblende, 74 
Hornblende-rock, 121, 126 
Hornblende-schist, 121, 126 
- Hornstone, 117 
Hornwort (Ceratophyllum), fossil, 875 
Horny texture of rocks, 87 
Horse, genealogy of, 625, 841, 842, 872; 
three-toed forms of, 841, 842, 868, 869, 872 
Human period in geology, 883 
Humus, formed from decomposing vegeta- 
tion, 305, 453, 458; supplies organic 
acids to spring water, 347 
Humus Acids (see Organic Acids) 
Hundsriickien, 702 
- Hungary, volcanoes of, 255, 861; glaciére 
in, 346 
Huron, Lake, terraces of, 901 
Huronian rocks, 645 
Hyzmoschus, 856 
Hyzxna, fossil, 873, 898, 905; in glacial 
period, 891; asa type-fossil, 616 
Hyznarctos, 864, 876 
Hyznictis, 878 
Hyznodon, 856, 869 
Hyalinia, 857 
Hyalomelan, 149 
Hybodus, 763, 775, 807 
Hydaspithertwm, 880 
Hydration of minerals, 333 
Hydraulic pressure of waves, 429 
Hydrobia, 874 
Hydrocarbons emitted from earth’s crust, 
03, 201, 236 
Hydrocephalus, 659 
Hydrochloric acid at volcanoes, 200 
Hydrofluoric acid, use of in petrographical 
analysis, 192 
Hydrofluosilicie acid, use of in petro- 
graphical analysis, 193 
Hydrogen in earth’s interior, 53; in crust 
and envelopes, 57; at volcanoes, 93, 200, 
252; sulphuretted in spring-water, 347, 
301; sulphuretted at volcanoes, 201, 235 
Hydro-mica-schists, 120, 123 
Hylzosaurus, 817 
Hylonomus, 754 
Hymenocaris, 651* 
Hymenophyllites, 748 
Hyolithus , 658, 666 
Hyopotamus, 841, 857, 869; 
fossil, 616 
Hyotherium, 863* 
Hyperodapedon, 763 
Hypersthene, 77 
Hypersthenite, 150 
Hypogene action, 196 
Hypsilophodon, 817 
Hypsiprimnopsis, 763 
Hyrachius, 856 
Hyracodon, 869 
Hyracotheriwm, 840, 857 
Hystrix, 878 
Hythe Beds, 818 
as a type- 
Ibex, fossil, 898 
Ice, effect of on climate, 25; effect of on 
temperature of earth’s crust, 46; kinds 
of, 110; terrestrial, 400 (see Glaciers) : 
of rivers and lakes, 461; on the sea, 
423; of the ice-foot, 424; of floes, 424: 
erosion by, 413, 434, 884, 886 : transport 
by on the sea, 436; contortion of strata 
by, 480, 488 
Ice-age, 883 (see Glacial Period) 
Ieeberes, formation of, 407, 425; 
logical action of, 434, "436 
Ice-cap, effects of transference of polar, 18, 
275 
Ice-falls, 404 
Ice-foot, 111, 424, 436 
Ice-sheet of glacial period, thickness of, 
886 
Ice-worn features of rocks, 414, 416, 884 
Iceland, transport of wind-borne yolcanic 
dust from, 219,326; sinter beds of, 354; 
volcanic phenomena of, 214, 219, 224, 
230, 236, 249, 259, 261 
Ichthyornis, 812, 813* 
Ichthyosaurus, 767, 777, 781*; as type- 
fossil, 615 
Ictitherium, 878 
Idaho, lava-fields of, 209, 256, 261 
Idocrase, 79 
Igneous (eruptive) rocks, 108, 129, 535; 
metamorphism of, 587 
Iguanodon, 807, 811* 
Ilex, 862 
Ilfracombe Group, 699 
Illznopsis, 667 
TIilenurus, 660 
Illenus, 664, 665*, 667 
Ilmenite, 69 
Imatra-stones, 488 
Impervious, defined, 344 
Inclination of rocks, 509 
Incrustations, calcareous, 354 : 
Indertsch, Lake, salinity of, 398 
India, volcanic plateau of Deccan, 258; 
heavy rainfall in, 369; coast bars of, 
387; cyclone waves of, 423; Archean 
rocks of, 646; Silurian, 693; Triassic 
770; Jurassic, 801; Cretaceous, 831; 
Cretaceous conformably and continu- 
ously followed by Tertiary strata up 
to Pliocene, 879; Hocene, 852; Miocene, 
869; Pliocene, 879 ; Glaciation in, 901 
Induration of rocks, by meteoric influences, 
333; by intrusion of eruptive rock, 573 
Indus, mud voleanoes of, 245; alluvial 
forms of, 381 
Infiltration products, 72, 167 
Infra-lias, 776 
Infra-littoral deposits, 438 
Infusorial earth, 168, 461 
Inoceramus, 799, 805, 806* 
Insect-beds, 787, 798 
Insects, fossil, 710, 732, 775, 780, 786, 792, 
796, 798, 800 
2e0- 
