482 
THE ANCIENT VOLCANOES OF GREAT BRITAIN 
62, 178, 180, 181, 195, 213, 234, 245 : ii. 27, 
49, 58, 79 
CnilKu 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 
Camming, J. G., ii. 22 
Cycles, volcanic, i. 27, 92 ; ii. 116 
I)ACITE, i. 230 ; ii. 185 
Dakyus, Mr. J. R., i. 90, 229, 272 ; ii. 10 
Dalmcllington, volcanic rocks at, i. 333 ; ii. 62 
Ualmeny type of'dolerite and basalt, i. 418, 420 
Dnlradian rocks, probable crushed necks of, 
i. 75, 125 ; lavas and sills of,. 121 ; green 
schists of, 124 
Hairy, Ayrshire, buried volcanoes of, i. 434 
Haim, J. 1 ),, ii. 189 
Darwin, 0., i. 27 
Daubrce, A., i. 72, 404 
Davies, J., 1. 156, 157 
Duchen, 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 Becho, 11., i. 142, 143, 170, 175, 204, 205, 
207, 259 ; ii. 9, 10, 19, 33, 95, 96, 97 
Dulessite, ii. 79 
Denudation, influence of, on volcanoes, i. 3, 4, 
8, 10, 43, 45, 46, 54, 08, 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, loadstones 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 ; Carbon- 
iferous volcanic rocks of, ii. 32 ; Permian 
volcanic rocks of, 94 
Diabase, i. 151, 153 (analyses), 156, 192, 194 
204, 200, 214, 217, 235, 240, 247, 249, 273 
(analyses), 278, 292, 318, 320, 330, 335, 344, 
345, 351, 403 ; ii, 5, 136, 415 
Diabase- porphy rite, i. 192, 204 
Diamond found in volcanic vents, i. 62 
Dick, Mr. A., jun., i. 380 
Dickson, Mr. K., 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 
Dittniar, 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, Dalvadian 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. (J. K., i. 68 ; ii. 267 
Dykes, vitreous margins of, i. 18 ; formation 
of, 64, 98 ; iu necks, 66 ; filled with agglo- 
merate, 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. S2 ; pre-Cambrian, 118; 
flow -structure in, 161; Cambrian, 156; 
Silurian, 187 , 216, 235,237, 248, 249; Old 
Red Sandstone, 277, 291, 338, 345 ; Car- 
boniferous, 40(1, 429, 460 ; ii. 1, 30 ; Permian, 
83 ; atriygdaloidal structure of, 85 
Tertiary, ii. 114 : arguments for their geo- 
logical age, 118, 125,171; geographical distri- 
bution, 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 ; por- 
phyritic and atnygdaloidal structures of, 128, 
129, 130 ; veins in, 130 ; joints iu, 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 char- 
acters of, 144 ; direction of, 145, 159 ; up- 
ward termination of, 147 ; known vertical 
extension of, 150 ; evidence of movement of 
molten rock of, 151 ; branches and veins 
from, 152 ; connection witli sills, 155 ; inter- 
secting, 158 ; compound or of moro than one 
infilling, 159 ; double, treble, and multiple, 
160, 318, 417, 439 ; compound, with basic 
and acid bands, 161,435 ; cnntact metamorph- 
ism of. 1 63 ; relation of, to geological struc- 
ture, 166; origin and history of, 175; Ice- 
landic example of, 261 ; example com- 
municating with cinder cone iu Utah, 268; 
connection of, with surface, 179, 269, 280 ; 
latest protrusions of, 381, 408, 416 ; ofgrano- 
phyre, 435, 436, 437, 439 
Eauth, condition of the interior of the, i. 10 ; 
fractures iu crust of the, 11 
Earthquakes, influence of, on early man, i. 1 ; 
transient effects of, 3, 8 
East Lothian, trachyte lavas of, i. 24 ; Carbon- 
iferous volcanic jilateau of, 370, 389, 403, 409 
Edinburgh, volcanic rocks near, i. 24, 102, 104, 
269, 273, 276, 279, 281, 285, 287. 2S9, 291. 
293, 311, 317, 318, 323, 364, 87". 373, 385. 
386, 387. 389, 410, 420, 436, 449 
Egan, Mr, l'\ W„ i. 212; ii. 201, 423 
Eifel, i. 4, 46, 58, 1 00 
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 
