ii. 300, 475

"Dimetian," i. 145 Dingle-beds, i. 346 Dingle, Upper Silurian nodular lavas of, i. 20, 254 Diorite, i. 78, 247, 249, 277, 278, 288; ii. 36 Dirrington Law, i. 290 Dittmar, Prof., ii. 137 Dolerite, i. 119, 134, 178, 190, 206, 230, 247, 261, 378, 403, 407, 417, 448; ii. 5, 11, 35, 49, 102, 103, 104, 125, 136, 157, 183, 271, 299, 303, 307, 319, 328 Dolgelli, i. 169, 178, 188 Donegal, Dalradian rocks of, i. 122; dykes in, ii. 124 Drogheda, volcanic rocks near, i. 244 Duffin, W. le S., ii. 426 Dumbarton, rocks near, i. 402, 404 Dumfoyn, a volcanic neck, i. 395, 398, 400 Dumgoyn, a volcanic neck, i. 395, 397, 398, 400 Dundee, sills and bosses near, i. 292, 306 Duneaton Water, volcanic rocks of, i. 329 Dunite, ii. 309 Du Noyer, G. V., i. 245, 250, 254; ii. 272, 426 Durham, Mr., i. 275 Durness Limestone, i. 112, 121, 123, 141 Dust, volcanic, i. 13 Dutton, Capt. C. E., i. 68; ii. 267 Dykes, vitreous margins of, i. 18; formation of, 54, 98; in necks, 66; filled with agglomerate, 70; grouping of, among intrusive rocks, 77; character of, 79; extent of, in Britain, 80; age of, 81; compound, 81; ii. 59; expulsion of lava from, i. 82; ii. 128; connected with the surface, i. 82; pre-Cambrian, 118; flow-structure in, 161; Cambrian, 156; Silurian, 187, 216, 235, 237, 248, 249; Old Red Sandstone, 277, 291, 338, 345; Carboniferous, 406, 429, 460; ii. 1, 30; Permian, 83; amygdaloidal structure of, 85 ---- Tertiary, ii. 114; arguments for their geological age, 118, 125, 171; geographical distribution, 121; two types of protrusion of, 122; nature of component rocks of, 125; external character of, 126; classification of basic, 129; enclosed fragments in, 129, 131, 144; porphyritic and amygdaloidal structures of, 128, 129, 130; veins in, 130; joints in, 132, 166; microscopic characters of, 134; chemical characters of, 137, 139; hade of, 139; breadth of, 139; interruptions of, 142; length of, 142; persistence of mineral characters of, 144; direction of, 145, 159; upward termination of, 147; known vertical extension of, 150; evidence of movement of molten rock of, 151; branches and veins from, 152; connection with sills, 155; intersecting, 158; compound or of more than one infilling, 159; double, treble, and multiple, 160, 318, 417, 439; compound, with basic and acid bands, 161, 435; contact metamorphism of, 163; relation of, to geological structure, 166; origin and history of, 175; Icelandic example of, 261; example communicating with cinder cone in Utah, 268; connection of, with surface, 179, 269, 280; latest protrusions of, 381, 408, 416; of granophyre, 435, 436, 437, 439

Earth, condition of the interior of the, i. 10; fractures in crust of the, 11 Earthquakes, influence of, on early man, i. 1; transient effects of, 3, 8 East Lothian, trachyte lavas of, i. 24; Carboniferous volcanic plateau of, 370, 389, 403, 409 Edinburgh, volcanic rocks near, i. 24, 102, 104, 269, 273, 276, 279, 281, 285, 287, 289, 291, 293, 311, 317, 318, 323, 364, 370, 373, 385, 386, 387, 389, 410, 420, 436, 449 Egan, Mr. F. W., i. 242; ii. 201, 423 Eifel, i. 4, 46, 58, 100 Eigg, Isle of, ii. 115; pitchstone of, 185, 217, 242, 445; brecciated basalt in, 189, 192; basalt plateau of, 215, 234; Scuir of, 217, 234, 447; sills of, 318; acid bosses of, 403; acid sills of, 431; proofs of subsidence at, 447; enormous denudation of, 239, 447, 458 Eildon Hills, i. 375 Electric Peak, i. 79, 82, 84 Elvans, i. 249, 281 Engulphment craters, i. 58 Ennerdale, granite of, i. 236 Enniscorthy, volcanic rocks near, i. 245 Environment, influence of, on early man, i. 1 Eozoic period, i. 110 Epidiorite, i. 118, 124, 129, 184, 247, 249 Erosion, laws of, i. 101 Eruptions, transient effects of, i. 3; old submarine, how ascertained, 48; lacustrine, 49; fluviatile, 49; terrestrial, 50; evidence of intervals between, 283, 287, 300, 442; ii. 42, 59, 203, 205, 221, 251, 254, 287 Erzeroum, old volcanoes near, i. 32 Eskdale Dyke, ii. 127, 133, 136, 137, 140, 143, 145, 146, 153 ---- (Lake District), granite of, i. 236 Etheridge, Mr. R, jun., ii. 24 Etna, i. 2, 4, 10, 55; ii. 261 Eurite, i. 188 Europe, basalt plateaux of north-western, i. 51, 52; ii. 181; pre-Cambrian disturbances of north-western, i. 117 Explosion-craters, i. 58; ii. 266 Explosions, volcanic, i. 246; ii. 196, 266, 425, 472 Extrusive rocks, defined, i. 14; textures of, 78

Fair Head, sills of, ii. 301 Farey, J., ii. 9 Farne Islands, ii. 2 Faroe Isles, basalt plateaux of, i. 52, 102; ii. 191, 192, 194, 256; vents in, i. 63; ii. 293; dykes of, 122, 133; tuffs and lignites of, 258; sills of, 322; absence of gabbro bosses in, 355; subsidence of, 447; dip of basalts in, 448; proofs of denudation in, 458 Faujas St. Fond, ii. 109, 112 Faults, connexion of volcanic vents with, i. 69; ii. 65; boundary, i. 294, 303, 305, 369; ii. 169; effects of, i. 446; ii. 200; connection with, dykes, 168 ---- of Tertiary basalt-plateau, ii. 452 Felsite (Felstone), Torridonian, i. 120; Uriconian, 130, 133; of Malverns, 134; Cambrian, 151, 160, 161, 164, 165, 167, 168; Silurian, 184, 199, 205, 206, 207, 210, 212, 218, 231, 232, 246, 247, 252, 255; Old Red Sandstone, 276, 277, 291, 293, 321, 327, 335, 346; Carboniferous, ii. 36, 49; Permian, 85; Tertiary, 174, 369, 424, 446 Felsitic breccia, ii. 195 ---- type of devitrification, i. 19 Felspar, ejected crystals of, i. 181; ii. 58, 79; large porphyritic crystals of, in dykes, 129, 135 Fife, Old Red Sandstone volcanic rocks of, i. 307; Carboniferous volcanic rocks of, 428, 429, 430, 433, 437, 448; Permian volcanic rocks of, ii. 56, 69 Fingal's Cave, i. 25; ii. 210 Fisher, Rev. O., i. 98 Fishguard, volcanic rocks at, i. 205 Fissure type of volcanoes, i. 42, 52; ii. 108, 115, 267 Fissures, volcanic, i. 42, 52, 53, 54, 425; ii. 141, 145, 159, 176; filled with agglomerate, i. 70; filled with dykes, 81, 118; compound, 82, ii. 159; pre-Cambrian, i. 118, 119; Carboniferous, 425; Tertiary, ii. 141, 159, 176, 425; modern of Iceland, 262; cause of, 177 Fleming, John, i. 268 Flow-structure, i. 21, 157, 160, 161, 162, 184, 210, 232, 246, 248, 255, 315, 321, 327, 346; ii. 129, 152, 190, 191, 332, 369, 392, 402, 424, 437, 441 Foot, F. J., i. 316 Forbes, D., ii. 370 ---- Edward, ii. 66, 113, 114, 198 ---- J. D., ii. 112, 333, 372, 381 Forellenstein, ii. 332 Forest of Wyre coal-field, ii. 102 Forfarshire, volcanic rocks of, i. 285, 299; flagstones of, 299 Forster, M., ii. 113 Forth-basin, Carboniferous system of, i. 361; Carboniferous plateaux of, 370; Carboniferous puys of, 416, 427, 429, 430, 432, 434, 437, 440, 446, 462; Permian volcanoes of, ii. 55, 67 Foster, Mr. C. le Neve, ii. 10 Fouqué, Prof., i. 18, 21; ii. 134 Fox, Mr. Howard, ii. 36 Fox Strangways, Mr. C., i, 135 Fragmental volcanic rocks, i. 14; only arise from explosions which reach the surface, 57 (_see_ Agglomerates, Conglomerates, Tuffs) France, Tertiary volcanoes of Central, i. 4, 10, 29, 41, 45, 49, 58, 60, 70; ii. 31, 271, 281, 373; Carboniferous volcanic action in, i. 357 Frankland, Prof. E., i. 273, 278 Fundamental complex of oldest gneiss, i. 114, 115 ---- gneiss, i. 115

Gabbro, granulitic, ii. 329; banded structure of, i. 116; ii. 329, 354, 357, 476; coarse-grained massive, 330; pale varieties in veins, 330; gneiss-like aspect of, 342, 254, 358 ---- of Carrock Fell, i. 91; Silurian, 195, 206, 247; Devonian, 262; Tertiary, 84, 90, 116; ii. 307, 308, 309, 319, 327, 334, 349, 355, 358, 391, 406, 407 Gairloch, peculiar pre-Cambrian rocks of, i. 115, 117 Galapagos Islands, i. 27 Gallaston type of dolerite and basalt, i. 418 Galloway, granites of, i. 93, 95, 272, 277, 290, 331 Garabol Hill, differentiation at, i. 90 Gardiner, Miss, i. 95 Gardiner, Mr. C. J., i. 256 Gardner, Mr. Starkie, ii. 196, 198, 212 Garlton Hills, i. 102, 370, 377, 378, 379, 380, 386, 390, 405, 412 Garnet found in volcanic vents, i. 62 Garth Grit, i. 177, 185, 208 Gases dissolved in the volcanic magma, i. 13, 15, 72, 97, 99 Geikie, Prof. J., i. 277, 306, 308, 331, 336, 339, 340, 369, 375, 426;