The Ancient Volcanoes of Great Britain, Volume 2 (of 2)

The volcanic intercalations which diversify the Lower Carboniferous formations of Southern Scotland extend but a short way across the English Border, and although, over the moor...

Direction--Termination upward--Known vertical Extension--Evidence as to the movement of the Molten Rock in the Fissures--Branches and Veins--Connection of Dykes with Intrusive S...

The parish of Small Isles includes the islands of Eigg, Rum, Canna, Sanday and Muck (Map VI.). The fragmentary basalt-plateau which it contains, although the smallest of the who...

(1) _Interstratified Lavas and Tuffs._--It will be convenient to consider first the volcanic chronicle as it has been preserved in the south-west and south of Scotland, where th...

In the island of Eigg three small bosses or sheets of acid rock occur. That at the northern end rises through the Jurassic sedimentary rocks, and forms a bold cliff from 150 to...

By far the greater number of the dykes of the Tertiary volcanic series belong to the first group, and it is these more especially which will be discussed in the present and the...

It is in the island of Skye that the granophyre and granite bosses attain their largest dimensions and afford, on the whole, the most complete evidence of their structures and t...

The foregoing chapters comprise a connected narrative of the history of volcanic action in the area of the British Isles during the vast succession of ages from the early Archæa...

Although the Carboniferous system spreads over by far the larger part of the surface of Ireland, and is laid bare in many thousands of natural and artificial sections, it displa...

From the south of Scotland we need to pass to the extreme south-west of England before we again encounter a group of volcanic rocks which may be referred with some confidence to...

While the necks of dolerite or basalt cannot always be satisfactorily discriminated from bosses which may never have established a connection with the surface, there is no room...

All through the Inner Hebrides the base of the basalt-plateaux presents abundant examples of sills. The general parallelism of these intrusive sheets to the bedding of the Juras...

Among the more impressive lessons which the basalt-plateaux of North-Western Europe teach the geologist, the enormous erosion of the surface of this part of the continental area...

From the evidence which has been led in the foregoing chapters it is clear that during the later stages of the Palæozoic period there was a gradual enfeeblement of volcanic vigo...

The mountains of the island of Rum, rising as they do from a wide expanse of open sea, present one of the most prominent and picturesque outlines in the West Highlands (Map VI.)...

From the facts stated in the foregoing chapters concerning the structure of the basalt-plateaux of North-Western Europe, it is evident that in none of these areas have the erupt...

(_c_) _Rhyolites._--In the Antrim plateau a group of rhyolite bosses occurs, some of which have been claimed as superficial lavas. In some cases it can be demonstrated that they...

There are five districts in North-western Europe where the original widespread Tertiary lava-fields have been less extensively eroded than elsewhere, or at least where they have...

The largest, most picturesque, and to the geologist most important area of Tertiary gabbro in Britain, is that of Skye (Map. VI.). Though, like every other portion of the Tertia...

This largest and geologically most important of all the Scottish plateaux comprises the island of Skye, at least as far south as Loch Eishort, and the southern half of Raasay, b...

If a geologist were asked to select that feature in the volcanic geology of the British Isles which, more than any other, marks this region off from the rest of the European are...

Not only have the acid rocks been protruded in small and large bosses, they have also been injected as sills between the bedding-planes of stratified rocks, between the surfaces...

333. View of the crest of the Cuillin Hills, showing the weathering of the Gabbro along its joints and of a compound basic dyke which rises through it. (From a photograph by Mr....

Though of comparatively small extent, the granophyre bosses of the island of Mull afford to the geologist a large amount of instruction in regard to the relations of the differe...

The materials that fill this vent consist of a typical agglomerate composed entirely, or almost entirely, of volcanic detritus. The embedded blocks vary up to eight feet in diam...

varieties of rhyolite. No undoubted example has yet been observed of a superficial rhyolite-lava, though such not improbably appeared in the interval between the lower and upper...

The mere fact that in many places the lower members of the series of terrestrial lavas have been submerged under the sea may be taken to prove a subsidence since older Tertiary...

This plateau covers nearly the whole of the island of Mull, embraces a portion of Morven on the Argyleshire mainland, and, stretching across Loch Sunart, includes the western pa...

Besides bosses and sills, the acid rocks of the Inner Hebrides take the form of Dykes and Veins which have invaded the other members of the volcanic series. Some of these have a...

The classification of the rocks which best harmonizes the field-evidence and the detailed study of their mineralogical composition, is one that arranges these volcanic protrusio...

It is one of the most interesting points in the Tertiary volcanic history that, in spite of the enormous geological revolutions that have passed since they became extinct, the s...

Since the publications of Macculloch, the occurrence of beautiful varieties of highly basic rocks among the igneous masses of the Western Isles has been familiar to geologists....

The phenomena of the coasts of Skye are repeated on the east side of Raasay, in Eigg, and still more magnificently along the south coast of Mull. A single example is here given...

We are now in a position to draw, from the observations which have been given in this and the preceding chapter regarding the different areas of gabbro in the Tertiary volcanic...

First to be examined, and now most familiar to geologists, are the remarkable sheets that underlie the plateau of Antrim, and project at various parts of the picturesque line of...

contain rounded blocks of Torridon sandstone and other rocks, which must have been carried from the east by some tolerably powerful river that flowed across the basalt-plains du...

The chief district for the display of volcanic eruptions that may be assigned to the Permian period lies in the centre of Ayrshire and the valleys of the Nith and Annan. But, fo...

Sandwich Islands, lava-cones of, i. 10 Sanidine ejected from volcanic vents, ii. 58, 79 Sanquhar, Silurian volcanic rocks at, i. 192, 195, 199; Permian volcanic rocks at, ii. 62...

In the Faroe Islands the actual base of the volcanic series is nowhere visible. Hence, the great lower platform of intrusive sheets being there concealed, this feature of the ba...

"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 Dittmar, Prof.,...

We have now to consider the structure and history of those volcanic masses which, during Tertiary time, were ejected to the surface within the area of the British Islands, and n...

PERIPATUS. By Adam Sedgwick, M.A., F.R.S. MYRIAPODS. By F. G. Sinclair, M.A. INSECTS. Part I. By David Sharp, M.A. Cantab., M.B. Edin., F.R.S.

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 vo...

Though I have not observed any features among the Tertiary basalt-plateaux of the British Isles that can be compared to the remarkable rifts and subsidences of Iceland, it can b...

185, 189, 190, 223, 224, 247, 269, 281, 284, 285, 309, 310, 318, 320, 334, 339, 347, 348, 368, 382, 384, 385, 387, 389, 392, 407, 408, 409, 413, 415, 433, 434, 437, 441, 446 Har...

(_a_) _Basalts and Dolerites._--In external characters these rocks range from coarsely crystalline varieties, in which the constituent minerals may be more or less readily detec...

Various opinions have been expressed regarding the connection between the amorphous eruptive rocks of the hill-groups and the level basalt-sheets of the plateaux. Jameson, thoug...

Geographical Changes at the Close of the Carboniferous Period--Land- and Inland-Seas of Permian time--General Characteristics and Nature of the Materials erupted--Structure of t...

We now come to the examination of another distinct phase of volcanic action during Tertiary time in Britain. The igneous rocks that have been under consideration in the foregoin...

this alteration has been produced by the intrusion of the gabbro or of some concealed mass of granophyre underneath, of which only projecting dykes and veins reach the surface,...

Ulster, Old Red Sandstone volcanic rocks of, i. 314 Ultra-basic rocks, i. 14, 118, 377, 417 Unconformability, deceptive case of, i. 163 Urgneiss, i. 110 Uriconian volcanic rocks...

Bass Rock, i. 372, 373, 403 Bassenthwaite Lake, i. 335 Bathgate, puy eruptions of, i. 440, 442, 445, 456, 461 Bauer, Dr. M., i. 62 Bauxite, ii. 197, 204 Bayley, Mr. W. S., ii. 3...

Carboniferous Limestone, origin of, i. 357 ---- system, subdivisions of, in Britain, i. 358, 360, 366; ancient geography of, 355, 361, 362, 432, 462; flora and fauna of, 356 ---...

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, Carbonifero...

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 Plat...

56, 58, 65, 66, 68, 94, 95, 102, 103, 118, 121, 125, 127, 144, 145, 148, 162, 164, 170, 174, 175, 190, 192, 199, 201, 203, 253, 272, 277, 292, 347, 384, 391, 420, 422, 423, 426,...

Returning now to the consideration of the acid rocks as these manifest themselves in the volcanic areas of Britain, I would remark that three distinct types of structure may be...

points to earliest eruptions of a vent, ii. 76 Nordenskjöld, Mr. O., i. 120 North Berwick Law, i. 371, 373, 403 North, Mr. Barker, ii. 244 Norway, eruptive rocks of, i. 28 Nunea...

Cuillin 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 Cumming, J. G., ii....

We have now followed the distribution of the basalt-plateaux, the arrangement of their component materials which were erupted at the surface, and the character of the dyke-fissu...

While the plateaux are built up mainly of successive flows of basaltic lavas, they include various intercalations of fragmental materials, which, though of trifling thickness, a...

In singular contrast to the nearly flat basalts of the plateaux, another series of rocks rises high and abruptly above these tablelands into groups of dome-shaped, conical, spir...

Wilson, Mr. A., ii. 49 Winch, N. T., ii. 113, 147 Witham, H. T. M., ii. 113, 238 Wood, N., ii. 113 Woods, Mr. H., i. 204 Woodward, Dr. Henry, ii. 449 Woodward, Mr. H. B., ii. 32...

_NATURAL SCIENCE._--"This second volume of the Cambridge Natural History is certain to prove a most welcome addition to English Zoological literature. It deals with a series of...

inward dip of rocks towards, i. 73, 352; ii. 80; connection of, with bosses, i. 93; ii. 276, 284; entombment and exposure of, i. 434; connection of with valleys, 272, 366, 375;...

_DAILY NEWS._--"Promises to be, in its own department of science, the most important work of the day.... This large and exhaustive work is written especially for general readers...

Genèvre, Mont, i. 194 Geological action, supposed former greater intensity of, i, 139 ---- contrasts, i. 103 ---- history, i. 109, 113 ---- Survey of Great Britain, i. 113, 115,...

subdivisions of, in S. W. England, 94; volcanic phenomena of, i. 46; ii. 55; lavas and tuffs of, 57, 58; vents of, 62, 67, 70, 96; sills of, 91, 100 Permo-carboniferous strata,...

Direction--Termination upward--Known vertical extension--Evidence as to the movement of the Molten Rock in the Fissures--Branches and Veins--Connection of Dykes with Intrusive S...

There can be no doubt that considerable alterations of level have taken place over the volcanic areas of North-Western Europe since the eruptions that produced the basalt-platea...

Geographical Changes at the Close of the Carboniferous Period--Land and Inland-Seas of Permian time--General Characteristics and Nature of the Materials erupted--Structure of th...

Sahlite found in volcanic vents, i. 62 Saline Hill, volcanic vents of, i. 433, 435, 440 Sanday, basalts of, ii. 215; conglomerates of, 226 Sandstone altered into quartzite, i. 7...