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;