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
Idahoe, 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