490 
THE ANCIENT VOLCANOES OF GREA T BRITAIN 
Small Isles, basalt-plateau of, ii. 215 ; vents of, 
288 ; sills of, 318 ; acid bosses of, 403 ; acid 
sills of, 431 
Small, Mr. E. IV., 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 
Sol way, Carboniferous volcanic plateau of, i. 
375, 385, 413 
Somerset, volcanic rocks of, ii. 32 
Soimna, 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 
Steelier, Dr., i. 421, 451 ; ii. 165 
St. Hilda, dykes oi, ii. 173, 416 ; gabbro of, 
358 ; general account of geology of, 405 ; 
granophyre of, 408 
Stocks, or bosses, i. 78, 88 
Stralmn, Mr. A., i. 171 ; ii. 10, 12, 23, 28, 32 
Strathaird, ii. 123, 140, 164, 269 
Strathbogie, i. 344 ; ii. 121 
Strathmore, i. 304 
Strom boli, 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, Archaean volcanic rocks of, i. 120 
Syenite, ii. 366 
Symes, Mr. R. G. i. 311, 343, 369; ii. 201, 
428 
Tatis, G., ii. 3, 113 
R., ii. 204 
Tatlock, Mr. R. R., i. 273, 278 
Tawney, E. B., i. 157 
Teall, Mr. J. J. H., i. 90, 114, 116, 117, 118, 
119, 120, 156, 192, 194, 200, 207, 210, 
275, 277, 290, 311, 336, 338, 346, 407, 449 ; 
ii. 2, 3, 5, 7, 11, 32, 44, 113, 131, 134, 135, 
137, 138, 140, 144, 149, 292, 293, 329, 367, 
368, 369 
Teesdale, i. 228 
Termier, M. P., ii. 375 
Terrestrial volcanic eruptions, i. 50 
Tkrtiarv Volcanic Series, ii. 181 
Subaerial character of eruptions, ii. 103, 198 
Scenery of, ii. 255, 256, 349, 391, 405, 408 
The Plateaux, ii. 183, 249 ; lavas of, 183, 218, 
236,256; thickness of individual sheets, 192. 
206, 254, 257 ; lenticular character of lavas 
of, 1 93, 257 ; greatest depth of, 210, 211, 213, 
260 ; tuffs and clays of, 194, 202, 204, 211. 
222, 225, 251, 258, 277, 284. 287 ; noil- 
volcanic fragments in, 196, 211, 213, 219 ; 
lignites of, 198, 203, 208, 213, 251 ; gravels 
and conglomerates of, 198, 212, 238, 256 ; 
coal of, 213, 251, 256, 287 ; leaf-beds of, 204. 
212, 222, 225, 288 ; carbonaceous nature of 
the upper parts of intercalated sediments in, 
223,. 226, 227, 229, 232, 251, 288 ; evidence 
for intervals between the eruptions in, 203. 
205, 208, 221, 228, 240, 245, 251, 254, 288 : 
no evidence of great central vents in. 
208, . 214, 255, 258, 260, 267 ; faulted 
condition of, 200, 208, 209, 452 ; subsidences 
of, 205, 208, 209, 214, 447 ; ancient river 
channels of, 217, 228, 231, 234, 456 ; 
volcanic cones of, 202, 218, 230, 277, 281. 
285 ; paralleled by the modern Icelandic 
eruptions, 260 ; vents of, 202, 218, 230, 
270, 276 
The Basic sills, ii. 298, 304 
The Gabbro bosses, ii. 327, 349, 355, 358 ; 
history of the gabbro intrusions, 359 
Tlio Acid rocks, ii. 364 ; petrography of, 
366 ; history of their investigation, 371 : 
analogies with trachytes of Central France. 
373 ; intruded at base of the gabbros or of 
the bedded basalts, 337, 353, 357, 431, 
432, 444 ; bosses of Skye, 378 : of Mull, 
395 ; of Small Isles, 405 ; of St. Hilda, 
405 ; of Arran, 418; of Carlingford, 420 ; 
of.Slieve Foye, and Barnavave, 421; of 
Slieve (billion, 422 ; of Antrim, 426 ; acid 
sills, 430 ; acid dykes and veins, 437 
Metamorphism of the basalts, ii. 272, 276, 
337, 339, 340, 347, 355, 356, 357, 358, 362, 
378, 383, 386, 397, 399, 400, 404, 413 
Texture, varieties of, in igneous rocks, i. 78, 
449 ; ii. 5, 299, 360 
Tholciitos, ii. 1 37, 158 
Tholeiite type of basalt, i. 419, 421 
Thornhill, volcanic rocks of, ii. 60 
Thoroddsen, Tb,, ii. 261, 262, 263. 264, 265, 
266, 278 
Thrust-planes, i. 229 
Time in geological history, ii. 107, 461, 465 
Timmins, J. H. , i. 133 
Tinto, i. 278, 288, 329 
Titterstone Clee liill, ii. 101 
loadstones of Derbyshire, i. 359 ; ii. 8 
Toplev, W., 1 147; ii. 3, 5, 7 
Torridonian rocks, i. Ill, 112, 113, 120; ii. 350 
Tortworth, volcanic rocks at, i. 288 
lonrmakoady, volcanic rocks of Bala age at, i. 
251 6 
Townson, R., i. 363 
Trachyte, i. 1S3, 230, 246, 273, 276 (analysis), 
379 (analysis), 386, 403, 407, 421 ; ii. 36, 47, 
96, 138, 152, 184, 236 
Traill, Mr. W., ii. 175, 421, 422 
Traprain Law, i. 372, 380, 403, 405 
Traquair, Dr. R. H., i. 266 
Tremadoc group, i. 1 14, 177 
Trevelyan, W. C., ii. 3 
Triassic eruptive rocks, i. 29 ; geography, ii. 
108 
i Trichites, i. 19 ; ii. 136 
