INDEX 
Aa form of lava in the Sandwicli Islands, ii. 
187 
Abereiddy Ray, i. 206 
Abich, H., i. 32 ... 
Acid igneons rocks, silica percentage ot, 1. 14 ; 
devitrification of, 19 ; flow-structure of, 21 ; 
occur in thicker sheets than basic, 24 ; alterna- 
tions of, with basic, 28, 61, 152, 157, 16o, 
207, 213, 233, 284, 318 ; ii. 236, 266, 278 ; 
metamorpliic action of, i. 95, 96 ; connection 
with mountains, ii. 98 ; scenery of, lOt. 
Acids, mineral, at volcanoes, i. 72 
Acland, Mr. H. I)., i. 133 _ 
Aegean Sea, volcanoes of, i. 1 _ 
Agglomerates, i. 31, 57, 58 ; in dykes, /0 , 
Arcluean, 120, 130, 185 ; Cambrian, 148, 149, 
167 ; Silurian, 17S, 180, 181, 184, 185, 194, 
199 206, 214, 237, 241, 244, 247, 253, 255 ; 
Old Red Sandstone, 279, 285, 289, 300, 313, 
395 338 349, 352 ; Carboniferous, 381, 
399’, 402, 404, 427, 429, 439, 440 ; ii. 13, 24, 
os 29 • Permian, 62. 64, 99 ; tertiary, 
194, 277, 278, 281, 289. 292, 293, 384, 400, 
423’ 
Allan, T., i. 363 
Allotriomorphic minerals, i. 21 . 
All port, Mr., i. 95, 130, 131, 260, 4ol ; 11. 11, 
42,102,103,104, 106,370 
Amber in Tertiary volcanic series, _ ii. 198 _ 
America, Western North, volcanic rocks ot, i. 
10, 100; ii. 267 
Amygdales, origin of, i. 15 ; ii. 1S9, 221, 285, 290 
Amygdaloidal structure, i. 15, 16, 17, 59, 2/4, 
385 ; ii. 3, 31, 57, 129, 188^ _ 
Analyses of Cambrian tutis, 1. 148, 149 ; 
of Cambrian diabases, 153; of Old Red 
Sandstone diabases, 274 ; ot Old Red Sand- 
stone andesites, 275 : of Old Red Sandstone 
trachytes, 270 ; of Old Red Sandstone fel- 
sites, 278 ; of Carboniferous limburgite, 377_; 
of Carboniferous basalts, 379 ; of Carboni- 
ferous trachytes, 380 ; of Carboniferous pho- 
nolite, 381 ; of Tertiary trachyte, ii. 139 ; of 
Tertiary dacite, 244 
Anderson', Dr. Tempest, ii 261, 262, 203 
Andesite, i. 24, 131, 136, 164, 165, 167, 178, 
180 184, 189, 190, 204,-212, 213, 214, 215, 
229' 230, 245, 246, 247, 252, 274, 275, 
(analyses), 277, 292, 300, 306, 309, 315, 318, 
395 330, 333, 345, 377, 379, 386, 403, 421 ; 
ii. 45, 57, 96, 125, 137, 184, 236, _ 424 
Anglesey, gneisses and schists of, 1. 126; vol- 
canic rocks of, 189, 219 
Anhydrite deposits, ii. 54 
Annandale, Permian volcanic rocks of, ii. 56, 
. 58, 60, 61, 66 , . 
Antrim, Old Red Sandstone volcanic rocks ot, 
i 314; Tertiary volcanic rocks of, 47,52; ii. 
109, 110, 113, 189, 140, 199 ; basalts of, 192, 
193* 199 202, 206 ; clays and iron-ore of, 
204’; rhyolites of. 185, 364, 370, 371, 426, 
445 ; deceptive agglomerate of, 188 ; rhyo- 
litic conglomerate of, 195, 206 ; plateau of, 
199 ; tuffs of, 202, 204 ; vents of, 271, 277 ; 
sills of, 298 ; central subsidence of basalt- 
plateau of, 448 
Apatite, ii. 135 
Apjohn, J., ii. 42 
Appleoross, volcanic vents in, ii. 292 
Arans, the, i. 175, 176, 179, 184, 186, 207 
Archaean period, i. 110, 111 ; volcanic rocks 
of, 120 .. 
Ardnannirchan, dykes and veins of, 11. 154, 
320 ; basalt-plateau of, 208 ; vents of, 287 ; 
sills of, 318 ; gabbro of, 355 
Arenig group, i. 175 ; lower limit of, 177, 18o ; 
top of, 178, 228, 246 
volcano of, i. 42, 175, 176, 179, 186, 20/^ 
rocks in Scottish Highlands, i. 123, 126 , 
in Merionethshire, 176, 179 ; of Shropshire, 
189 ; of Ayrshire, 196 ; of Scottish High- 
lands, 201 ; of Anglesey, 221 ; of Lake dis- 
trict, 229 ; of Ireland, 239 
Argyll, Duke of, ii. 113, 114, 198 
Argyllshire, dykes of, ii. 127, 128, 138, 142 
146, 171, 172 ; vents of, 278 _ 
Arizona, explosion crater in, i. 58 ; laccolites 
in, 86 . . c ■ 
Arran, Old Red Sandstone volcanic rocks ot, 1. 
298, 311 ; Carboniferous volcanic rocks ot, 
386! 392 ; possible Permian volcanic rocks ot, 
ii. 58 ; grauite of, i. 93 ; ii. 366, 36/, 418; 
pitehstone of, i. 19 ; ii. 44o ; dykes of, 1- , 
139, 140, 142, 146, 154, 161 .. 
Arthur Seat, i. 364, 373, 378, 385, 386 ; 11. 6/ 
“ Arvonian,” i. 145, 156 
Asbestos in volcanic breccia, 11. 51 
Ascension Island, cellular lava or, 1. 15 
Ashes, volcanic (see Tulls) 
Ashprington volcanic series, i. 262 
Asphalt, ii. 79 
Atherstone, i. 170 
Augite, loose crystals of, in volcanic vents, i. 
62, 178, 181 ; ii. 58, 79; lumps of, in vol- 
canic vents, i. 352 
Augite-aplianites, i. 1^8 _ t 
Auvergne, old volcanoes of, i. 29, 32, 66, /0, 
100 ; ii. 373 
