Chapter LI: Summary and General Deductions (2)

Cadell, Mr. H. M., i. 114, 423; ii. 334
Cader Idris, volcanic rocks of, i. 42, 175, 176, 177, 178, 179, 180,
181, 182, 188, 207
Caer Caradoc, i. 131, 132, 170
Caerfai group (Cambrian), i. 155
Caernarvonshire, volcanic rocks of, i. 159, 207
Caithness Flags, i. 343, 352
---- volcanic vents in, i. 352
Calciferous Sandstones, i. 361, 366, 415
Calcite as a matrix of tuffs, ii. 27, 39, 41
Caldecote volcanic rocks, i. 170
Callaway, Dr. C., i. 126, 130, 132, 134, 220, 221
Calton Hill, lavas and tuffs of, i. 373, 378, 385, 386, 389
Cambrian system, i. 112, 123, 133, 139, 143, 144;
volcanoes of, 145, 159
Campbeltown, volcanic rocks of, i. 312, 386
Campsie Fells, i. 102, 368, 369, 384, 386, 389, 393, 397, 398, 400, 403,
410, 412, 447
Canary Islands, i. 27
Canna, basalts of, ii. 184, 187, 190, 215, 216;
vent in, 288
Cantyre, volcanic rocks of, i. 311, 369, 370, 386
Caradoc group, i. 175, 196
Carbonaceous rocks, influence of, on igneous masses, i. 95, 426, 449, 456;
ii. 65, 87, 104, 165
Carboniferous Limestone, origin of, i. 357
---- system, subdivisions of, in Britain, i. 358, 360, 366;
ancient geography of, 355, 361, 362, 432, 462;
flora and fauna of, 356
---- volcanic plateaux, distribution of, i. 364, 367;
nature of materials constituting, 377;
structure of, 383;
bedded lavas and tuffs of, 383;
vents of, 54, 394, 399
---- Puys, i. 46, 47, 308, 364;
of Scotland, 414;
nature of the materials erupted by, 416;
necks of, 424;
bedded lavas and tuffs of, 417, 436, 440;
sills of, 446, 472;
bosses of, 458, 465;
dykes of, 460;
of Derbyshire, ii. 8;
Isle of Man, 22;
of Somerset, 32;
of Devonshire, 32;
of King's County, 37;
of Limerick, 41
Carlingford, igneous rocks of, i. 96; ii. 175, 371, 420
Carnedd Dafydd, i. 209
Carnmony Hill, ii. 272
Carrock Fell, differentiation in rocks of, i. 91;
metamorphism at, 94, 96;
as a volcanic boss, 235, 236
Cement-stone group, i. 362, 366, 387, 418, 462
Cellular structure of volcanic rocks, i. 15, 33
Chalk, metamorphism of, by a dyke, ii. 164
Champernowne, A., i. 260, 262
Charnwood Forest, i. 134; ii. 53
Cherts associated with volcanic rocks, i. 123, 167, 169, 173, 174, 184,
196, 197, 240, 254; ii. 25, 36
Cheviot Hills, i. 102, 271, 272, 274, 275, 277, 278, 290, 293, 336
Chilled margin in intrusive rocks, i. 81, 83; ii. 126, 158, 160, 172,
299, 303, 310, 317, 321, 392, 402
Christiania, eruptive rocks of, i. 28
Chronology, volcanic, how determined, i. 46
Clark, Mr. G. T., ii. 180
Claystone, i. 277, 279, 318, 324, 327; ii. 403
Cleavage, effects of, on igneous rocks, i. 162, 165, 224, 231, 232, 234,
237, 260, 261; ii. 36
Clee Hills, ii. 101, 102
Cleveland Dyke, ii. 1, 122, 139, 140, 142, 144, 146, 147, 150, 153, 167,
168, 169
Clough, Mr. C. T., i. 114, 201, 236, 274, 290, 337; ii. 123, 124, 127,
128, 132, 137, 138, 142, 145, 146, 152, 162, 171, 172, 316, 384, 437
Clyde, Carboniferous volcanic plateau of, i. 368, 384, 385, 393, 400,
407, 411
Coal interbedded among volcanic rocks, i. 392, 423; ii. 198, 213, 251, 287
---- alteration of, at volcanic vents, i. 72; ii. 64
---- alteration of intrusive rocks by, i. 95, 451
---- alteration of by sills, dykes, etc., ii. 67, 164, 166
Coal-measures, i. 358, 360, 366
Coalbrookdale Coal-field, ii. 103
Cole, Prof. G. A., i. 176, 177, 178, 179, 180, 181, 184, 187, 188, 210,
211; ii. 134, 205, 212, 245, 370, 371, 378, 426
Colorado, Grand Cañon of, i. 30;
laccolites of, 86
Columnar structure, i. 25, 27, 343, 378, 385, 459; ii. 164, 186, 206, 301
Comley Sandstone, i. 144
Cones, volcanic, connection of, with necks, i. 70;
contemporaneous denudation of, 73; ii. 202, 218, 230;
entombment of, i. 433, 463; ii. 66
Conglomerates, volcanic, i. 31, 37, 183, 190, 286, 300, 307, 309, 310,
314, 315, 330, 341; ii. 195, 198, 218, 284
Coniston Limestone, i. 229, 231
Contemporaneity in Geology, 201
Continents, origin of, i. 11
Contraction, effects of terrestrial, i. 12, 97, 98
Conybeare, J. J., ii. 95
---- W., i. 171; ii. 9, 95, 110, 113, 199
Cooling, effects of, in inducing varieties of texture in igneous rocks,
i. 78, 79, 81; ii. 274, 275, 299, 303, 310, 317, 392, 402
Coon Butte, Arizona, i. 58
Cork, County, volcanic breccias of, ii. 49
Corndon, sill of, i. 176, 189, 190
Corston Hill, i. 373, 386, 387
Craiglockhart type of dolerite and basalt, i. 418
Crater, consolidation of tuff within a, i. 429
Crater-lakes, i. 58; ii. 266, 275
Cretaceous period, geography of the, ii. 108, 182
Cross Fell, i. 228, 229, 238
Cross, Mr. Whitman, i. 86
Crush-conglomerates or breccias, i. 32, 220, 223, 225, 244; ii. 281,
347, 352
Crushing, mechanical effects of, i. 315 (_see_ Schist)
Crust, contraction of the terrestrial, i. 12, 97, 98;
oldest rocks of, 110;
deformation of, 117, 121, 264, 295, 297
Cryptocrystalline type of basalt, i. 419
Crystallites of volcanic rocks, i. 18
Crystals, different periods of formation of, in volcanic rocks, i. 19, 20,
21, 421; ii. 128, 131, 134, 135;
ejected by volcanic vents, i. 62, 178, 180, 181, 195, 213, 234, 245;
ii. 27, 49, 58, 79
Cuillin Hills, scenery of, i. 106;
gabbro of, ii. 329, 361;
acid rocks of, 391
Culots, i. 78, 88
Culm-measures, ii. 33
Cumbrae Islands, i. 368, 369, 378, 407
Cumming, J. G., ii. 22
Cycles, volcanic, i. 27, 92; ii. 116

Dacite, i. 230; ii. 185
Dakyns, Mr. J. R., i. 90, 229, 272; ii. 10
Dalmellington, volcanic rocks at, i. 333; ii. 62
Dalmeny type of dolerite and basalt, i. 418, 420
Dalradian rocks, probable crushed necks of, i. 75, 125;
lavas and sills of, 121;
green schists of, 124
Dalry, Ayrshire, buried volcanoes of, i. 434
Dana, J. D., ii. 189
Darwin, C., i. 27
Daubrée, A., i. 72, 404
Davies, J., i. 156, 157
Dechen, H. von, i. 46; ii. 112, 280, 333, 340, 367, 372, 381
Deformation, effects of, on volcanic rocks, i. 75, 115, 117, 119, 121,
127, 129, 162
De la Beche, H., i. 142, 143, 170, 175, 204, 205, 207, 259; ii. 9, 10,
19, 33, 95, 96, 97
Delessite, ii. 79
Denudation, influence of, on volcanoes, i. 3, 4, 8, 40, 43, 45, 46, 54,
58, 71, 73, 75, 79, 87, 100-107, 370, 433, 434, 436, 476; ii. 55, 61,
62, 179, 181, 182, 241, 245, 248, 249, 255, 257, 282, 283, 292, 316,
317, 363, 373, 407, 455
Derbyshire, toadstones of, i. 359; ii. 8
Desmarest, ii. 373
Devitrification of volcanic rocks, i. 18, 19, 78; ii. 437, 446
Devonian system, i. 257;
volcanoes of, 259
Devonshire, volcanic scenery of, i. 103;
Devonian volcanic rocks of, 259;
Carboniferous volcanic rocks of, ii. 32;
Permian volcanic rocks of, 94
Diabase, i. 151, 153 (analyses), 156, 192, 194, 204, 206, 214, 217, 235,
240, 247, 249, 273 (analyses), 278, 292, 318, 320, 330, 335, 344, 345,
351, 403; ii. 5, 136, 415
Diabase-porphyrite, i. 192, 204
Diamond found in volcanic vents, i. 62
Dick, Mr. A., jun., i. 380
Dickson, Mr. E., ii. 23
Differentiation in igneous rocks, i. 22, 27, 84, 85, 90, 91, 449;
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;
ii. 57, 191, 259, 322
Genèvre, Mont, i. 194
Geological action, supposed former greater intensity of, i, 139
---- contrasts, i. 103
---- history, i. 109, 113
---- Survey of Great Britain, i. 113, 115, 118, 119, 121, 122, 123, 124,
125, 126, 129, 130, 133, 135, 142, 143, 144, 145, 159, 160, 166, 170,
171, 175, 176, 179, 181, 182, 183, 186, 187, 188, 190, 196, 198, 201,
204, 205, 207, 208, 212, 214, 215, 216, 217, 218, 219, 220, 221, 225,
227, 228, 232, 233, 238, 239, 240, 242, 243, 244, 245, 250, 251, 254,
259, 270, 275, 278, 294, 299, 306, 307, 308, 314, 315, 317, 318, 325,
329, 331, 336, 339, 340, 344, 346, 349, 350, 352, 364, 369, 372, 373,
375, 397, 403, 404, 406, 407, 411, 423, 425, 434, 449, 462, 475, 476;
ii. 3, 4, 9, 10, 12, 13, 16, 17, 20, 23, 33, 36, 37, 42, 43, 46, 48, 49,
56, 58, 65, 66, 68, 94, 95, 102, 103, 118, 121, 125, 127, 144, 145, 148,
162, 164, 170, 174, 175, 190, 192, 199, 201, 203, 253, 272, 277, 292,
347, 384, 391, 420, 422, 423, 426, 428, 433, 435, 446, 449
Giant's Causeway, ii. 80, 109, 186, 188, 192, 206
Gilbert, Mr. G. K., i. 87; ii. 362, 363
Girvan, i. 192, 200
Glaciation, absence of, in Devonshire, i. 261
Glass in volcanic rocks, i. 18, 33, 60, 78, 180, 211, 216, 230, 232, 235,
316; ii. 85, 120, 126, 133, 135, 137, 184, 204, 247, 272, 285, 316, 317
Globulites, ii. 135
Gloucestershire, Silurian volcanoes of, i. 238
Gneiss, analogies of, with igneous rocks, i. 93; ii. 476;
oldest, i. 110, 115
Godwin-Austen, A. C., i. 259, 262
Goodchild, Mr. J. G., i. 229, 449; ii. 150
Grainger, Rev. Dr., ii. 198
Grand Sarcoui, ii. 373, 374, 381
Granite, bosses of, i. 88, 90, 93;
plutonic and volcanic, 89;
metamorphism by, 95;
altered by dykes, ii. 164;
pre-Cambrian, i. 119;
post-Arenig in Highlands, 126, 310;
in Cambrian rocks, 155;
in Silurian rocks, 200, 229, 236, 238, 249;
of probably Old Red Sandstone age, 272, 277, 290, 331, 337;
Tertiary, ii. 366, 418, 420
Granitite, i. 188, 277, 290, 337; ii. 367
Granophyre, alteration of rocks by, i. 95, 96;
scenery of, 105;
solvent action of, 82, 84, 85, 96, 99; ii. 163, 392, 415, 422, 433;
brecciated, 382;
spherulitic, 381;
bedded structure of, 381, 403, 404;
apt to be intruded at the base of a volcanic series, 403;
shattering of rocks invaded by, 405, 411, 413, 416, 439;
veins of, 409, 410, 432, 437;
Silurian, i. 214, 215
---- Tertiary, i. 339; ii. 368, 395, 408, 430;
boundaries of, 382, 409;
relation to older vents, 280, 384, 399;
relation to plateau-basalts, 386, 396, 402, 404;
relation to gabbro, 391, 402, 404, 410;
relation to basic dykes, 395;
proof of liquidity of, 413;
sills of, 430, 436, 437;
dykes of, 435
Granophyric structure, i. 20; ii. 366
Graphite in Tertiary volcanic series, ii. 198
Graptolites, i. 174, 196, 197
Grauwacke or Devonian rocks, De la Beche on, i. 259, ii. 33
Graves, Lieut. T., ii. 451
Great Glen of Scotland, i. 121
Greeks, influence of volcanoes on, i. 1
Green, A. H., i. 133, 134, 163; ii. 10, 12
Greenland, Tertiary basalts of, ii. 182
Greenly, Mr. E., i. 129, 214
Greenock, Lord, i. 363
Green schists of the Scottish Highlands, i. 122;
of Anglesey, 129
Greenstone, i. 183, 187, 206, 217, 219, 249, 259, 261; ii. 34, 35, 37,
103, 104, 355
Greenstone-ash, i. 219
Griffith, Sir R., ii. 299, 422
Gunn, Mr. W., i. 114, 298, 311, 336, 369, 407, 410; ii. 58, 172, 420
Gypsum deposits, ii. 54

Hade of dykes, ii. 139
Hæmatitic iron-ore, ii. 197
Hall, Sir James, i. 72, 363
Hälleflinta, i. 131, 167
Hardman, E. T., ii. 365, 449
Harker, Mr. A., i. 90, 91, 93, 95, 96, 99, 188, 209, 210, 211, 212, 213,
214, 217, 218, 222, 227, 228, 230, 231, 232, 235, 236, 237, 238, 290;
ii. 124, 125, 126, 129, 130, 139, 144, 146, 160, 162, 163, 164, 174,
185, 189, 190, 223, 224, 247, 269, 281, 284, 285, 309, 310, 318, 320,
334, 339, 347, 348, 368, 382, 384, 385, 387, 389, 392, 407, 408, 409,
413, 415, 433, 434, 437, 441, 446
Harkness, R., i. 228; ii. 56
Harlech anticline, i. 159, 179, 187;
group, 176
Hatch, Dr. F. H., i. 183, 184, 187, 188, 229, 230, 246, 247, 248, 249,
261, 277, 278, 306, 377, 380, 381, 417, 419, 420; ii. 57, 96, 184, 274,
276, 299, 319, 332, 367, 368, 369, 370, 388, 398
Haughton, Prof. S., i. 346; ii. 422
Hawaii, lava-fountains of, i. 12;
differentiation in lavas of, 27;
lava-cauldron of, 58
Haworth, Mr. E., ii. 96
Hay Cunningham, R. I., i. 269, 317, 363, 372, 373, 449, 451; ii. 237,
238, 244
Heaphy, Mr. C., i. 432
Hebrides, basalt-sheets of, i. 24, 47, 52, 102;
acid rocks of, 95, 102;
gabbros of, 84, 90, 102;
scenery of, 105;
pre-Cambrian rocks of, 112, 114, 117, 121;
Cambrian land of, 141;
early observations on the Tertiary volcanic rocks of, ii. 109, 110, 111;
dykes of, 118, 146, 158, 174;
basalts of, 181, 186, 215;
pitchstone lava of, 238, 246;
plateau-scenery of, 249;
Tertiary rivers and lakes of, 217, 228, 231, 234, 252;
vents of, 274;
basic sills of, 304;
gabbro intrusions of, 327;
acid intrusions of, 364, 379, 430, 437;
dislocations of, 452;
denudation of, 455
Heddle, Dr., i. 274, 302; ii. 78, 79, 246, 307, 406
Helland, Prof. A., ii. 191, 261, 263, 264
Henderson, Mr. J., i. 449
Henry Mountains, laccolites of, i. 86; ii. 362
Henslow, J. S., ii. 22, 224
Heterogeneity in volcanic magmas, i. 85, 90; ii, 190, 334
Hett Dyke, ii. 1, 7, 147
Hibbert, S., i. 46
Hicks, Dr. H., i. 126, 145, 154, 158, 159, 166, 206
Hill, Mr. J. B., ii. 140
Hill, Rev. E., i. 135
Hinde, Dr. G. J., i. 198; ii. 35
Hinxman, Mr. L., i. 114, 344; ii. 121
Hobson, Mr. B., i. 260; ii. 23, 27, 96, 99
Holden, Mr. J. S., ii. 204
Holl, H. B., i. 133, 134, 170
Holland, Mr. P., i. 177, 178, 179; ii. 23
Hollybush Sandstone, i. 133, 170
Holocrystalline structure, i. 78; ii. 136, 184
Hopkins, W., ii. 177, 179, 268
Hornblende, ejected crystals of, i. 178, 181; ii. 49, 51, 58, 79
Hornblende-schists formed from basic igneous rocks, i. 75, 114, 118, 119,
124, 129
Horne, Mr. John, i. 114, 196, 199, 200, 344, 345, 375; ii. 23, 144, 292
Hornito of a lava-stream, i. 55; ii. 264
Hornstone, i. 131, 136, 277, 278 (analyses), 324
Houston Marls, i. 423, 436, 440, 444, 466
Howard, Mr. H. T., i. 207
Howell, Mr. H. H., i. 294, 307, 364
Hoy, Island of, i. 350
Hughes, Prof. T. M'K., i. 126, 144, 160, 161, 166, 168, 220, 222, 223, 227
Hull, Mr. E., ii. 42, 95, 103, 272, 421, 426, 449
Hurlet Limestone, i. 360, 366, 394, 410, 415, 444, 452, 456, 467, 470, 474
Huronian rocks, i. 111
Hutchings, Mr. W. M., i. 227, 230, 233
Hutton, James, i. 363; ii. 9, 110
Hutton, W., ii. 3
Hyperite, i. 279
Hysgeir, pitchstone of, ii. 246

Iceland, Tertiary basalts of, ii. 182, 260;
Tertiary gabbros and liparites or granophyres of, 261;
continuity of volcanic phenomenon of, 261;
lava-fields of, i. 24, 42, 53, 100; ii. 260;
lava-domes of, i. 10; ii. 265;
fissures of, i. 70; ii. 262, 271, 454;
dykes of, 122, 261;
cinder cones of, 264, 271;
subsidence of, 447
Idaho, lava-fields of, ii. 267
Iddings, Prof., i. 28, 29, 30, 78, 79, 82, 84, 90; ii. 128, 178
Idiomorphic crystals, i. 21, 417, 420; ii. 40
Index Limestone of the Scottish coal-fields, i. 360, 444, 452
India, fissure-eruptions of, i. 10;
volcanic plateau of, ii. 180
Intermediate volcanic rocks, silica-percentage of, i. 14
Intersertal structure, i. 417; ii. 136
Intrusive rooks, defined, i. 14;
occasional cellular character of, 16;
flow-structure in, 22, 161;
varieties of, 77;
textures of, 78, 449; ii. 274, 360, 392;
in sheets, sills, and laccolites, i. 83;
melting of rocks by, 82, 84; ii. 129, 163, 392;
consolidation of, i. 84;
banding of, 84, 450; ii. 329, 342;
heterogeneity of, i. 85; ii. 344;
metamorphism by, i. 94, 451;
influence of surrounding rocks on, 95;
conditions of their intrusion, 97;
columnar structure in, ii. 187, 291, 301
---- Pre-Cambrian, i. 116;
Cambrian, 156;
Silurian, 187, 195, 206, 216, 235, 237, 248, 249;
Devonian, 261;
Old Red Sandstone, 277, 291, 321, 335, 338, 343, 345;
Carboniferous, 406, 408, 420, 446; ii. 1, 21, 30, 33, 40, 48;
Permian, 58, 64;
Tertiary, 270, 298
Ireland, submarine eruptions of, i. 48;
Dalradian rocks of, 122, 123, 126;
Arenig rocks in, 123;
Silurian volcanic rocks of, 239, 251;
granites of, 290;
Old Red Sandstone volcanic rocks of, 346, 348;
Carboniferous volcanic rocks of, 359; ii. 37;
early observers among the Tertiary volcanic rooks of, 109;
Tertiary basalt plateau of, 364, 370, 371;
gabbros of, 359;
acid rocks of, 420
Iron-ore, pisolitic (Arenig), i. 181, 208;
Tertiary, of Antrim, ii. 204
Irvine, Mr. D. R., i. 294, 299
Irving, Rev. A., ii. 95
Isogeotherms, shifting of, i. 98
Italy, old volcanoes of, i. 4; ii. 474, 477

Jack, Mr. R. L., i. 294, 308, 369, 375, 396, 404; ii. 57, 145
Jameson, Robert, i. 268, 269, 317, 363; ii. 109, 161, 244, 333, 355, 364
Jan Mayen, ii. 182
Jedburgh type of dolerite and basalt, i. 418
Jennings, Mr. C. V., i. 176, 177, 179, 180, 181, 184, 185, 186, 187, 188
Johnston-Lavis, Dr., ii. 261
Joints in dykes, ii. 132
Judd, Prof. J. W., i. 157, 275; ii. 115, 116, 134, 137, 162, 185, 209,
211, 245, 247, 267, 274, 278, 280, 303, 307, 309, 315, 316, 319, 322,
328, 329, 332, 333, 349, 356, 360, 372, 388, 410, 439
Jukes, J. B., i. 143, 171, 175, 208, 218, 219, 245, 246, 250, 254, 316;
ii. 10, 20, 42, 47, 49, 101, 103, 105
Jurassic period, physical conditions of the, ii. 108, 182

Kelly, J., i. 314
Kenmare, Old Red Sandstone volcanic rocks of, i. 350
Keratophyre, i. 247
Kerrera, Isle of, i. 342
Kersantite, i. 261
Keswick, i. 229
Kildare, Chair of, Bala volcanic rocks at, i. 245, 256
Killarney, nodular lavas of, i. 20, 272, 346
Kilpatrick Hills, i. 385, 388, 403, 410
Kilroe, Mr. J. R., i. 251, 253, 315
Kilsyth type of dolerite and basalt, i. 418
Kinahan, Mr. G. H., i. 349; ii. 45, 49, 426
Kincardineshire, volcanic necks of, i. 281, 286, 293, 299;
Old Red Sandstone of, 301
King, Mr. Clarence, i. 27
King's County, volcanic necks of, ii. 37
Kippie Law type of basalt, i. 418
Kirkby, Mr. J., ii. 106
Kirwan, R., ii. 110
Knockfeerina, Old Red Sandstone volcanic rocks of, i. 349
Knocklayd, ii. 200
Kynaston, Mr. H., i. 343

Labyrinthodonts, i. 356
Laccolites, i. 77, 83, 86, 88, 98, 99, 190; ii. 363
Lacroix, Prof., i. 96
Lacustrine volcanic eruptions, i. 49
Lagorio, Dr. A., ii. 137
Lake, Mr. P., i. 177, 179
Lake-District, i. 227, 290;
Vesuvian cone of, i. 42, 45
"Lake Caledonia," i. 272, 294, 296
"Lake of Lorne," i. 341
"Lake Orcadie," i. 266, 271, 343, 350
Lakes, eruptions in, i. 49;
crater, 58;
of Old Red Sandstone, 264
Lambay Island, conglomerates of, i. 244
Lammermuir, granites of, i. 290, 340
Lamplugh, Mr. G. W., i. 32, 220; ii. 23, 28
Lamprophyre, i. 291, 293
Lanarkshire, i. 291, 368, 416
Land, sculpture of the, i. 101, 102
Landslips, ii. 200, 287
Lankester, Prof. E. Ray, i. 310
Lapilli, volcanic, i. 33, 34, 61, 151
Lapworth, Prof. C., i. 130, 132, 137, 171, 172, 189, 190, 196
Largs, volcanic vent near, i. 56, 396, 397, 401
Lasaulx, Prof. von, ii. 365, 371, 426
Laurentian gneiss, i. 110
Lavas, classification of, i. 14;
flow-structure of, 16, 21;
vesicular structure of, 17;
glass in, 18;
devitrification of, 19;
bedding of, 24;
effect of water on molten, 25, 334;
sack-like or pillow-structure of, 26, 184, 193, 201, 240, 244, 252;
seldom occur in solitary sheets, 26;
variations in structure in, 27;
sequence of, in eruptions, 28, 92, 377, 386;
crusts of, disrupted in volcanic explosions, 58, 59, 60; ii. 189;
alternations of acid and basic, i. 28, 61, 152, 157, 165, 207, 213,
284, 318; ii. 236, 266;
contrasted with intrusive rocks, i. 78;
sandstone veins in, 283, 300, 303, 320, 327, 333, 337; ii. 59, 98;
shattered or agglomerate structure of, 99;
metamorphism of, i. 231, 240, 338; ii. 272, 276, 337, 339, 340, 347,
355, 379, 386, 397, 399, 400, 404, 413
---- Cambrian, i. 152, 168
---- Silurian of Merionethshire, i. 183;
Scotland, 191;
Builth, 203;
Pembrokeshire, 205;
Caernarvonshire, 207;
Berwyn Hills, 218;
Anglesey, 219;
Lake District, 227;
Gloucestershire, 238;
Ireland, 239, 254
---- Lower Old Red Sandstone, i. 273, 281, 294, 317
---- Carboniferous, i. 377, 384, 417, 436, 440, 443; ii. 8, 18, 34, 45
---- Permian, ii. 68, 96
---- Tertiary, ii. 183;
types of, 186;
banding of, 189;
thickness of, 192;
lenticular character of, 193;
of Antrim, 199;
irregular bedding of the vitreous, 243
---- modern Icelandic eruptions of, ii. 261
Lava-domes, ii. 265
Lava-plug of volcanic funnels, permanence of, i. 40, 41, 55, 73, 76, 430
Lawson, Prof. A. C., i. 82
Leaf-beds, ii. 198
Lebour, Prof., i. 336; ii. 2, 3, 5, 7
Leckstone, i. 419, 442, 443
Lecoq, H., i. 45; ii. 373
Leinster granite, ii. 245, 249, 290
Lewisian Gneiss, i. 81, 110, 111, 113, 118
Liddesdale, Carboniferous volcanic vents of, i. 55, 416, 425, 440, 475
Life, earliest traces of, i. 140
Lignite in Tertiary volcanic series, ii. 198
Limburgite, i. 377, 408, 417, 420, 448; ii. 40, 46
---- type, i. 418
Limerick, Carboniferous volcanic rocks of, i. 421, 430; ii. 41;
Old Red Sandstone volcanic rocks of, i. 348
Limestone, metamorphism of, i. 72, 451; ii. 14, 22, 164, 280, 383
Lindley and Hutton on Eigg conifer, ii. 238
Lingula Flags, i. 144, 177
Linlithgowshire (_see_ West Lothian)
Lintrathen, porphyry of, i. 277, 292, 311
Lion's haunch type of dolerite and basalt, i. 418
Lithomarge, ii. 197, 204
Lizard, rocks at the, i. 194
Llanberis, Pass of, i. 159, 163
---- group, i. 144
Llandeilo group, i. 175, 196, 242;
volcanic rocks of, 186, 202, 221, 227, 241
Llandeiniolen, i. 160
Llandovery group, i. 175, 196;
possible volcanic rocks of, 238
Llangadock, i. 205
Llangefni, i. 220
Llanllyfni, i. 161
Llanwrtyd, i. 204
Lleyn Peninsula, i. 208, 209, 213, 215
Lloyd Morgan, Prof., i. 145, 147, 154
Llyn Padarn, i. 157, 159, 160
Loch Carron, pre-Cambrian rocks of, i. 115, 117
Loch Lomond, dykes at, ii. 180
Loch Tay Limestone, i. 122, 124, 125
Lomas, Mr. J., ii. 191, 322
Longulites, ii. 135
Lonsdale, W., i. 257
Longmyndian rocks, i. 111, 129, 132
Lorne, volcanic rocks of, i. 102, 271, 281, 341
Lough Mask, Silurian volcanic rocks of, i. 251
---- Nafooey, Silurian volcanic rocks of, i. 251
---- Neagh, subsidence of site of, ii. 201, 205;
history of, 448
Ludlow group, i. 175
Lycopods, fossil, i. 174

Maare, volcanic, i. 58; ii. 287, 288, 296
Macconochie, Mr. A., ii. 58
Macculloch, John, i. 95, 269, 270; ii. 22, 111, 113, 123, 140, 154, 156,
159, 172, 174, 175, 213, 217, 231, 237, 244, 251, 280, 293, 304-307,
310, 314, 315, 327, 349, 364, 371, 403, 406, 408, 409, 418
Macknight, Dr., i. 268, 317
Maclaren, Charles, i. 269, 317, 325, 363, 372, 373, 451, 462; ii. 67
M'Henry, Mr. A., i. 32, 240, 242, 244, 314, 347; ii. 201, 204, 272, 293,
426, 427, 428, 429
M'Mahon, General, i. 260; ii. 35, 36
Magma, volcanic, explosive energy of, i. 13;
gases and vapours dissolved in, 13, 72, 97, 99;
differentiation of, 22, 84, 91;
solvent action of, 82, 84, 85, 99; ii. 392, 415, 422, 433;
heterogeneity of, i. 85, 90, 91; ii. 344, 360, 476;
metamorphic action of, i. 94;
alteration of, by incorporation of foreign material, 96;
ii. 386, 390, 392;
conditions for the injection of, i. 97, 99
Magnesian Limestone, ii. 54
Malvern, pre-Cambrian volcanic rocks of, i. 133;
Cambrian volcanic rocks of, 169
Man, Isle of, Carboniferous volcanic rocks of, ii. 22
Manod, i. 184
Marl Slate, ii. 54
Marl, volcanic, i. 423, 436, 440, 444, 466
Marr, Mr. J. E., i. 227, 228, 230, 231, 232, 236, 237, 238, 290; ii. 189
Matlock Bath, ii. 13, 22
Mediterranean, earthquakes and volcanoes of, i. 1
Melaphyre, i. 131
Mello, Mr. J. M., ii. 22
Melrose, rocks near, i. 397, 398, 400, 425
Melting of rocks by igneous intrusions, i. 82, 84, 85, 96, 99; ii. 163,
392, 415, 422, 433
Menai Strait, i. 159
Menevian group, i. 114
Merse, volcanic plateau of the, i. 375
Metamorphism of tuffs, i. 157;
of lavas (_see_ under Lavas)
---- by lavas, i. 27;
by sills and bosses, 87, 94, 95, 216, 236, 331, 338, 431; ii. 7, 22,
36, 131, 148, 163, 299, 300, 310, 337, 339, 340, 347, 355, 356, 357,
358, 362, 378, 383, 386, 397, 399, 400, 404, 413
---- in vents, i. 67, 71, 82, 93, 399, 404; ii. 39, 78, 292
---- around vents, i. 72, 349, 350, 352, 399, 404, 432; ii. 76, 272, 273,
276, 280, 292
---- regional, i. 121, 123; ii. 35
Mica, ejected crystals of, in volcanic breccias, ii. 49, 58, 79, 80
Mica-porphyrite, i. 277, 338
Michel Lévy, M., i. 18, 21, 46, 88; ii. 373, 374
Microgranite, i. 131, 215, 235, 249; ii. 367, 437
Microlites of igneous rocks, i. 18, 21, 33; ii. 135, 275
Micropegmatitic structure, i. 20, 418, 449; ii. 5, 368, 437
Microscopic examination of rocks, i. 18, 21
Midlands, eruptive rocks of English, ii. 100
Midlothian, Carboniferous volcanic plateau of, i. 373, 385, 387;
sills of, 446
Miller, Hugh, ii. 237
---- Mr. H., i. 336
Mills, Abraham, ii. 109
Millstone grit, i. 358, 360, 366
Minette, i. 277, 278, 291, 293
Minto Crags, i. 375, 397
Mitchell, Rev. Hugh, i. 301
Moel Siabod, i. 175
---- Wyn, i. 175, 176, 184, 185
Monckton, Mr. H. W., i. 449; ii. 224
Montana, lava-fields of, ii. 115, 267
Montrose, volcanoes of, i. 299
Moray Firth, basin of, i. 271, 343
Morton, Mr. G. H., i. 189
Morven, basalt-plateau of, ii. 208
Mountain-chains, origin of, i. 11, 12, 98
Mourne mountains, granite of, i. 93; ii. 124, 366, 367, 420
Muck, Isle of, ii. 215
Mud-lava, ii. 85
Mudstone, volcanic, i. 423, 436, 440, 444, 466; ii. 86, 222, 258
Mull, branching amygdales of, i. 17;
perlitic glass from, 19;
pale lavas of, ii. 184, 213;
basalt of, 188, 192, 193;
breccias of, 196;
plateau of, i. 24, ii. 208;
non-volcanic breccias in, 196, 211;
flint gravel in, 211;
leaf-beds of, 212;
vents in, 274, 278;
gabbro of, 355;
acid bosses of, i. 20; ii. 395;
acid sills of, 430;
acid dykes and veins of, 443;
enormous denudation of, 457, 461
Murchison, R. I., i. 113, 121, 129, 142, 173, 175, 189, 204, 205, 207,
238, 257; ii. 56, 95
Mynydd-mawr, i. 209, 211, 216
Mythology, influence of earthquakes and volcanoes on, i. 2

Nant Francon, i. 161
Naples, puys of, i. 100, 429
Napoleonite, i. 22
Necker, L. A., ii. 112, 123, 139, 140, 146
Necks, volcanic, i. 56;
of fragmentary materials, 56;
of non-volcanic detritus, 57, 289, 343, 426;
of agglomerate, 58; ii. 276;
internal stratification in, i. 63; ii. 80, 294;
with central lava-plug, i. 64, 430;
with dykes and veins, 66, 430; ii, 291;
of lava-form material, i. 67, 430; ii. 271;
parasitic, i. 69;
connection of, with cones, 70, 435; ii, 70, 89, 277, 281, 290;
metamorphism of, i. 67, 71, 82, 93, 399; ii. 39, 78;
metamorphism of rocks around, i. 72, 349, 350, 352, 399, 404, 432;
ii. 76, 272, 273, 274, 276, 280, 292;
inward dip of rocks towards, i. 73, 352; ii. 80;
connection of, with bosses, i. 93; ii. 276, 284;
entombment and exposure of, i. 434;
connection of with valleys, 272, 366, 375; ii. 61, 65;
relation between their size and the character of the agglomerate, 76;
connection of, with sheets of tuff or lava, 70, 89, 277, 284
---- Silurian, i. 215, 235;
Old Red Sandstone, 277, 288, 293, 311, 318, 323, 328;
Carboniferous, 394, 399, 400, 404, 406, 424, 465; ii. 13, 28, 47;
Permian, ii. 62, 67;
Tertiary, ii. 202, 270, 276
Neptunist and Plutonist controversy, i. 363; ii. 67, 95, 110, 112
New Mexico, necks in, i. 68
Newry granite, i. 290
Nicholson, Prof. Alleyne, i. 228, 229
Nicol, James, i. 311, 369
---- W., ii. 238
Nigrine, ii. 79
Nithsdale, Permian volcanic rocks of, ii. 58, 60, 62, 65
Nodular structure of lavas, i. 20, 162, 204, 206, 207, 211, 232, 247,
255, 274, 346
Nolan, Mr. J., i. 240, 251, 315; ii. 423, 424, 425
Non-volcanic debris, among volcanic rocks, i. 31, 57, 289, 313, 345, 381,
399, 402, 422, 426, 437; ii. 18, 27, 28, 58, 64, 76, 78, 99, 195, 196,
281, 423;
indicates comparatively feeble eruptions, i. 57, 289, 345, 426, 438;
ii. 293;
points to earliest eruptions of a vent, ii. 76
Nordenskjöld, Mr. O., i. 120
North Berwick Law, i. 371, 373, 403
North, Mr. Barker, ii. 244
Norway, eruptive rocks of, i. 28
Nuneaton, i. 171

Obsidian, i. 18, 19; ii. 370
Ochil Hills, i. 274, 276, 277, 279, 281, 286, 287, 288, 293, 303, 308, 311
Oil-shales of the Lothians, i. 361, 362, 462
O'Kelly, J., i. 349; ii. 49
Oldham, T., ii. 299
Old Red Sandstone, lines of vents in, i. 69;
granite protrusions of, 236, 272, 277, 290, 337;
of County Waterford, 251;
distribution in Britain, 257;
an exceptional stratigraphical type, 258;
conditions of its deposit, 259, 263, 297;
original scenery of, 265;
vegetation of, 265;
isolation of the water-basins of, shown by fossil evidence, 265;
classification of, 260;
history of the investigation of, 268;
volcanic centres in, 271;
nature of volcanic products in, 273;
structure of lavas and tuffs of, 281;
volcanoes of, 259, 263, 294, 303, 323, 325, 337, 341, 343, 346, 348, 352;
subdivisions of, 297;
thickest conglomerates of, 301;
composition of conglomerates of, 302, 315, 341;
unconformabilities in, 267, 328, 333;
Upper division of, 348, 375, 383; ii. 42
Olenellus-zone, i. 112, 130, 132, 140, 144
Olenus-zone, i. 144
Olivine, i. 154, 418, 420; ii. 58, 135
Omagh, i. 315
Ophitic structure, i. 21, 417; ii. 136, 184, 274
---- type of dolerite, i. 418, 421
Oregon, crater lake in, i. 58
Orkney Isles, i. 271, 344, 350; ii. 121
Orthoclase, ejected crystals of, ii. 79
Orthophyre, i. 273, 276, 277, 308
Osann, A., ii. 191
Oyenhausen, C. von, ii. 112, 280, 333, 340, 367, 372, 381

Palæopicrite, i. 261
Palæozoic systems, i. 139;
volcanic rocks resemble modern, i. 30
Palagonite, i. 33, 61, 151, 180, 246, 422, 423; ii. 44, 46, 57, 223
Paradoxides-zone, i. 144
Paramorphism, i. 249
Peach, Mr. B. N., i. 114, 128, 147, 168, 191, 192, 195, 196, 197, 198,
199, 200, 216, 240, 277-294, 307, 308, 329, 331, 344, 345, 369, 375,
425, 426, 476; ii. 133, 145
Pebidian, i. 145
Pegmatite, i. 20, 119, 127, 418, 449; ii. 5, 368, 437
Pembrokeshire, volcanic rocks of, i. 145, 159, 205
Penmaen-mawr, i. 209, 215
Pennant, T., ii. 109
Pennine chain, ii. 8
Pentland Hills, volcanic series of the, i. 102, 269, 273, 276, 279, 281,
285, 287, 289, 291, 311, 317
Perlite, i. 130
Perlitic structure, i. 19, 196, 199, 206, 211, 216, 232, 274
Permian system, geographical conditions accompanying the deposition of,
ii. 53, 97;
subdivisions of, in S. W. England, 94;
volcanic phenomena of, i. 46; ii. 55;
lavas and tuffs of, 57, 58;
vents of, 62, 67, 70, 96;
sills of, 91, 100
Permo-carboniferous strata, ii. 54
Petersen, Dr., i. 275, 336
Phillips, J., i. 133, 170, 205, 238; ii. 3
---- J. A., i. 260, 261
---- W., i. 171; ii. 95
Phonolite, i. 380 (analysis); ii. 375
Phyllite, i. 162, 222
Picrite, i. 377, 417, 420, 448, 450; ii. 57
---- type, i. 418
Pillow-structure in lavas, i. 26, 184, 193, 201, 240, 244, 252;
ii. 189, 259
Pitchstone, i. 18, 19, 130; ii. 134, 174, 204, 238, 242, 246, 370,
437, 444
Plagioclase, ejected crystals of, ii. 79
Plants fossil, in tuffs, i. 392; ii. 113, 198, 212, 222
Platania, G., i. 26
Plateau-type of volcanoes, i. 42, 100, 308, 341, 364
Plateaux, Carboniferous, of Scotland, i. 364;
distribution of, 367;
composition of, 377;
structure of, 383;
lavas and tuffs of, 383;
vents of, 394;
dykes and sills of, 406;
close of eruption of, 410;
Tertiary, ii. 181;
formation of modern Icelandic, 265
Player, Mr. J. H., analyses by, i. 377, 381; ii. 138, 330
Playfair, John, i. 363; ii. 110
Plinthite, ii. 197
Pliocene (supposed) of Lough Neagh, ii. 449
Plutonic operations of volcanoes, i. 77;
granite, 88
Plutonists and Neptunists, i. 363; ii. 67, 95, 110, 112
Pomeroy, volcanic series near, i. 315
Porphyrite, i. 190, 193, 207, 229, 240, 252, 273, 274, 377, 379
Porphyritic structure, i. 19, 274; ii. 128
Portlock, J. E., ii. 110, 111, 113, 199, 201, 299, 364
Portraine, conglomerates at, i. 244
Portrush, shells in supposed basalt at, ii. 110, 299
Potstone, i. 125
Pre-Cambrian rocks, i. 111, 121, 126
Pressure, experimental proof of effects of, i. 24
Prestwich, Sir J., ii. 103
Propylites, ii. 185, 388
Proterobase, i. 247
_Pterygotus_, i. 265
Pumice in tuffs, i. 244, 422; ii. 17, 27, 28, 32, 44, 46, 286, 288;
in volcanic necks, i. 60, 180; ii. 17, 39, 195
Pumiceous structure, i. 15, 33, 34, 60
Puys, as a type of volcano, i. 10, 44, 100, 414;
probable subærial nature of some, 432;
Carboniferous, 308, 364, 414, 424, 463; ii. 13, 28, 34, 47;
Permian, ii. 62;
Tertiary, 271, 276
Puy de Chopine, i. 32; ii. 374
---- Dôme, ii. 373
---- Montchar, i. 32
---- Pariou, i. 66, 70; ii. 31, 281
Pyroclastic detritus, i. 31, 58, 61
Pyromeride, i. 211
Pyrope, ii. 58, 79
Pyroxene, ii. 135

Quartz-porphyry, i. 19, 156, 159, 160, 161, 165, 277, 291, 314; ii. 96,
369, 420, 423, 430, 431
Quartz-trachyte, ii. 371
Quartzite, i. 112, 170

Raasay, basalt of, ii. 192;
neck-like breccias in, 293;
acid sill of, 430
Raddling or red-staining of rocks, i. 250, 261
Radiolarian cherts, i. 123, 167, 169, 173, 174, 184, 196, 201, 244
Rain-pittings in strata, i. 342
Raisin, Miss, i. 161, 163, 164, 165, 210
Ramsay, A. C., i. 126, 142, 143, 144, 145, 158, 159, 168, 175, 176, 177,
178, 179, 180, 182, 183, 204, 205, 208, 210, 212, 214, 223, 237, 364
Ratho type of dolerite, i. 418, 421
Red Head, section at, i. 300
Red Hills, Skye, scenery of, i. 105; ii. 379
Reed, Mr. Cowper, i. 205
Reid, Mr. Clement, ii. 449, 450
Renard, Prof. A., i. 148, 149
Renfrewshire, Carboniferous volcanic rocks of, i. 368, 385, 397, 400, 404,
408, 416, 430, 447
Reyer, Prof. E., ii. 474
Reynolds, Mr. S. H., i. 177, 179, 256
Rhobel Fawr, i. 177, 178, 186
Rhyolite, i. 19, 22, 24, 131, 161, 165, 167, 168, 178, 204, 210, 231, 232,
255, 276, 278; ii. 185, 205, 371, 424, 437
Rhyolitic conglomerate, ii. 195, 206, 429
Richardson, Rev. W., ii. 110
Richthofen, F. von, i. 28; ii. 115, 116
Rivers made to shift their channels by volcanic eruptions, i. 42, 49;
of the Tertiary volcanic period, ii. 217, 228, 231, 234, 456
Rocks, oldest known, i. 110
Roscommon, volcanic rocks of, i. 316
Rosenbusch, Prof. H., ii. 136, 137
Ross, Mr. Alexander, ii. 406, 409
Rothliegende, ii. 95
Roxburghshire, Carboniferous vents of, i. 55, 403, 404
Rubers Law, i. 375, 380, 404
Rum, i. 112;
basalt-plateau of, ii. 215;
gabbros of, 332, 349;
acid bosses of, 403;
acid sills of, 431;
pitchstone of, 445
Rutley, Mr. F., i. 131, 133, 170, 207, 210, 227, 231, 232, 238, 260;
ii. 23, 35

Sahlite found in volcanic vents, i. 62
Saline Hill, volcanic vents of, i. 433, 435, 440
Sanday, basalts of, ii. 215;
conglomerates of, 226
Sandstone altered into quartzite, i. 72, 349, 350, 404, 432, 451;
ii. 76, 164;
veinings of, in lava, i. 283, 300, 303, 320, 327, 333, 337;
ii. 59, 98
Sandwich Islands, lava-cones of, i. 10
Sanidine ejected from volcanic vents, ii. 58, 79
Sanquhar, Silurian volcanic rocks at, i. 192, 195, 199;
Permian volcanic rocks at, ii. 62
Santorin, ii. 134
Saponite, ii. 79
Scenery, origin of, i. 8, 100
Schalstein, i. 262; ii. 36
Schists, primeval, i. 110, 114, 118, 119;
produced by deformation of igneous rocks, 75, 114, 118, 119, 121, 162,
240, 249, 252, 261
Schmidt, Dr. C. W., ii. 266
Scoriaceous structure, i. 15, 16, 282, 327, 339
Scorpions, fossil, i. 174, 356, 466
Scotland, lines of fault in, i. 11;
Vesuvian cones of, 42;
plateaux of, 43;
puys of, 46;
submarine lavas of, 48;
Carboniferous vents of, 55;
volcanic scenery of, 104;
pre-Cambrian rocks of, 111;
Cambrian rocks of, 112;
Lewisian gneiss of, 114;
Dalradian rocks of, 121;
Arenig rocks of, 123, 191;
Old Red Sandstone of, 266, 273, 281, 291;
Carboniferous geography of, 356;
Carboniferous volcanoes of, 359;
Carboniferous plateaux of, 367;
Carboniferous puys of, 414;
Permian volcanoes of, ii. 55;
Tertiary dykes of, 122;
Tertiary basalt-plateaux of, 208, 274, 304;
Tertiary gabbros of, 327;
Tertiary acid rocks of, 379
Scrope, G. P., i. 27, 82, 45, 116; ii. 373, 374, 381
Sedgwick, A., i. 142, 166, 175, 218, 227, 257; ii. 1, 2, 3, 5, 113,
139, 153, 157
Segregation (_see_ Differentiation)
Segregation-veins, i. 84, 92; ii. 66, 130, 300, 303
Selwyn, Mr. A. C. R., i. 143, 175, 208, 221
Semi-opal, ii. 79
Sepulchre Mountain, i. 79
Serpentine, i. 195, 293
Shale, alteration of, i. 72, 451; ii. 164
Shap, granite of, i. 236, 238, 271, 290
Sheets, intrusive (_see_ Sills)
Shelve, i. 176, 190
Shetland, i. 271, 289, 292, 293, 345
Shiant Isles, ii. 307
Shineton Shales, i. 144
Shore-lines, traces of ancient, i. 295, 305
Shropshire, ancient volcanic rocks of, i. 129, 189;
latest eruptive rocks of, ii. 101
Sicily, i. 26
Sidlaw Hills, i. 286, 294, 303
Sills, vitreous margins of, i. 18;
tectonic relations of, 77, 83, 451;
origin of name, 83;
differentiation (segregation) in, 81, 450; ii. 476;
ordinary stratigraphical position of, i. 85;
considered as parts of incompleted volcanoes, 86;
metamorphism by, 87, 94, 451; ii. 299, 303, 310;
conditions for injection of, i. 97, 98, 99, 458;
columnar structure of, ii. 187, 291, 301, 306, 308, 319;
amygdaloidal structure in, 299, 312;
banding of, 309;
split by later sills, 310, 316;
extreme subdivision of, 311;
slaggy surface in some, 312;
give off veins, 313;
double and multiple, 318, 434;
connection with vents, 322
---- pre-Cambrian, i. 118, 124;
Cambrian, 155, 170, 171;
Silurian, 187, 195, 206, 216, 237, 249;
Devonian, 261;
Old Red Sandstone, 277, 291, 321, 335, 343, 345;
Carboniferous, 408, 446, 472; ii. 2, 21, 30, 48;
Permian, 64, 66;
of Midlands, 102, 103;
Tertiary, (1) Basic, 298;
(2) Acid, 366, 430
Silurian system, i. 173;
vegetation of, 174;
geography of, 263;
volcanoes of, 175;
classification of, 175;
two volcanic series of, 177
---- volcanoes in Shropshire, i. 189;
in Scotland, 191;
at Builth, 203;
in Pembrokeshire, 205;
in Caernarvonshire, 207;
in the Berwyn Hills, 218;
in Anglesey, 219;
in the Lake District, 227;
in Gloucestershire, 238;
in Ireland, 239, 254
Skae, H. M., i. 294, 299, 306, 375; ii. 57
Skiddaw, i. 228;
granite of, 236
---- Slate, i. 229
Skomer Island, i. 207
Skye, spherulitic dykes and sills of, i. 20;
ophitic structure from, 20;
basalt-terraces of, 24;
metamorphism by granophyre of, 95, 96;
volcanic scenery of, 103, 105;
dykes of, ii. 123, 124, 129, 139, 140, 146, 150, 152, 154, 160, 162,
164, 165, 173, 269;
bedded basalts of, 192, 249, 269;
tuffs of, 251;
connection of dykes and superficial lavas in, 269;
vents in, 280;
sills of, 304;
gabbro bosses of, i. 116; ii. 334;
acid bosses of, 379;
acid sills of, 431;
acid dykes of, 437;
pitchstone veins of, 445;
subsidence of, 447
Slaggy structure, i. 16, 33, 59, 282, 327, 339; ii. 98, 187
Slane, volcanic rocks near, i. 244
Slate-tuffs, i. 180, 213, 234
Slemish a volcanic neck, ii. 271
Slieve Foye, ii. 421
---- Gallion, ii. 200
---- Gullion, ii. 422
Small Isles, basalt-plateau of, ii. 215;
vents of, 288;
sills of, 318;
acid bosses of, 403;
acid sills of, 431
Small, Mr. E. W., i. 207
Smaragdite found in volcanic vents, i. 62
Snowdon, volcanic rocks of, i. 20, 42, 47, 102, 175, 208, 209, 210, 211,
212, 213, 218, 226
Soda-felsites, i. 183, 196, 247
Solfataric action, i. 71; ii. 185, 205, 388
Sollas, Prof., i. 96; ii. 175, 293, 415, 421, 422
Solway, Carboniferous volcanic plateau of, i. 375, 385, 413
Somerset, volcanic rocks of, ii. 32
Somma, denudation of, i. 3, 100
Spheroidal structure of dolerite, i. 456
Spherulitic structure, i. 19, 20, 95, 120, 130, 155, 162, 184, 211, 232,
235, 346; ii. 369, 381, 392, 432, 435, 437, 441, 446
Spilosite, i. 262
Springs, mineral, connected with volcanic action, i. 390, 445
St. Abb's Head, i. 338
Staffa, i. 25;
first notice of, ii. 109;
columnar basalts of, 186, 188, 210;
basalt conglomerate of, 195
Staffordshire, latest eruptive rocks of, ii. 101, 103
St. Andrews, old volcanoes near, ii. 71, 73, 87
St. David's, Cambrian volcanic rocks of, i. 145
---- Head, i. 205
Steam in volcanic action, i. 13, 15, 16, 71
Stecher, Dr., i. 421, 451; ii. 165
St. Kilda, dykes of, ii. 173, 416;
gabbro of, 358;
general account of geology of, 405;
granophyre of, 408
Stocks, or bosses, i. 78, 88
Strahan, Mr. A., i. 171; ii. 10, 12, 23, 28, 32
Strathaird, ii. 123, 140, 164, 269
Strathbogie, i. 344; ii. 121
Strathmore, i. 304
Stromboli, i. 4
Sublimations, traces of ancient, i. 445
Submarine eruptions, i. 48
Sub-ophitic structure, i. 417
Subsidence and volcanic action, i. 295, 297, 444, 463; ii. 42, 205,
447, 470
Subterranean igneous injections, i. 77 (_see_ Bosses, Dykes, Sills)
Suess, Prof. E., ii. 474
Sun-cracks, i. 342
Sweden, Archæan volcanic rocks of, i. 120
Syenite, ii. 366
Symes, Mr. R. G., i. 311, 343, 369; ii. 201, 428