;24 



N.l TURE 



\_Atig. 20, 1874 



we may not even call it possible. But not the less are wc bound 

 to look to that day, and to labour for it as a crowning triumph 

 of Science, when Theoretical Mechanics shall be recognised as 

 the key to every physical enigma — the chart for every traveller 

 throuah the dark infinite of Nature. 



SKCTION C 



Opening Address of the President, Prof. Edward 



Hui.1., F.R.S. 



On the Voicanic Phtiiimena ef County Antrim and adjoining 



Districts. 



Following the example of several Piesidents of the Geolo" 

 gical Section of the British Association, I purpose commencing 

 our proceedings by an address, selecting for my subject the 

 votcanic phenomena of the district in which we are assembled. 

 But before entering upon this subject, 1 am sure it will be equally 

 in accordance with your feelings and my own if I give expression 

 to the general and deep regret which is felt at the death (so little 

 expected) of the late President of this .Section, Prof John 

 Phillips, of Oxford, on April 24, in the 74th year of his age. 



Tlu late Prof. PJiillifs. — As the nephew and pupil of Mr. 

 Wdliam Smith, " the Father of English Geology," Prof 

 Phillips v/as nurtured in an atmosphere of geological science 

 which accorded well with his own tastes ; and in his youth was 

 the companion and assistant of his uncle in many a surveying- 

 tour in the east and north of England. His subsequent appoint- 

 ment as Keeper of the Museum at York,and one of tlie secretaries of 

 the Yorkshire Philosophical Society, gave him opportunities and 

 scope (or pursuing his inquiries — ulliirately resulting in the pub- 

 lication of his laborious work on "The Geology of Yorkshire,'' 

 a woik not only abounding in local details, but containing the 

 germs of several generalisations on questions relating to physical 

 geokigy. 



Of his connection with the Geological Survey of Great Britain, 

 Prof. Phillips has left two enduring monuments in his v/ork on 

 "The Palaeozoic Fossils of Cornwall, Devon, and West Somer- 

 set," and thai on "The iMalveru Hills and surrounding districts " * 

 — one dealing with the organic structures, and the other more 

 especially with the physical conditions of the south and west of 

 England. 



To his future career as Professor of Geology in the University 

 of Dublin, afterwards, on the death of Dr. Buckland, in th.e 

 University of Oxford, or as President of the Geological Society of 

 London in 1S59 and of the British Association at Birmingham in 

 i£j5, it is unnecessary for me in this brief notice to do more than 

 ali.de. Through these years and down to the time of his decease 

 his .''--rtile brain and ready pen were ever at work. But the scojie 

 of his investigations was not limited to purely geological sub- 

 jects ; he was a man of many parts, and astronomical questions 

 largely engaged his attention in his later years. In 1S6S he 

 visited Italy and Vesuvius, and subsequently published a little 

 work on the history and structure of that mountain in a form very 

 acceptable to that lari;e por:ion of the travelling British public 

 which at one time or another makes the delightful pilgrimage to 

 the workshop of Vulcan and the Phlegrxfan Fields. 



The loss of Prof. Pliillips' presence at the meetings of '.the 

 British Association, of which he was one of tlie founders, is irre- 

 parable. His genial face and lucid words brought sunshine 

 wherever he appeared, and threw liglit on eveiy topic he handled ; 

 to him might well be applied tue words — "quidquid tetigit 

 oinavit." \\ hile lamenting his loss, let us endeavour to imitate 

 the example of his untiring industry, his patient pursuit of the 

 beautiful and noble in nature, his honesty of character, his purity 

 of life. + 



The Volcanic District of the North-east oj Ireland. — I have now 

 to direct your attention to the district of County Antrim and its 

 neighbourhood as one claiming our special investigation, and pre- 

 senting a multitude of interesting problems connected with the 

 volcanic phenomena of the Tertiary period. By the labours ol 

 Berger, Weaver, Portlock, Griffith, Bryce, Tate, Holden, and 

 other geologists, many of these problems havejeceived a solution ; 

 others remain for further discussion. It shall be my endeavour 

 to give you a brief summary of the facts and inftiences arrived at 

 up 10 this time, and to present you with a coiinecled history of 



* " The Malvern Hills compared with the Palacoic dislrigls of Abbcrlcy, 

 Woolhope, May Hill, Toit«orth, and Usk," Mcni. Geol. Survey, 1849. 



t An interesting memoir of the late Prof. Phillips will be found iii the 

 ecolu£-uat M-ngtii-me, vol. vii. p. 301 (1870). 



the operations carried on by ten'estrial agents in this island, from 

 the commencement of the volcanic era to its close. 



This era, though short as compared with the sum of geologic 

 time, was in reality vastly extended, and comprised within its 

 limits several stages or divisions characterised by special physical 

 conditions. Spe-ikiug in geological terms, it probably included 

 the latter part of the Eocene and the whole of the Miocene 

 periods, interrupted by long pauses in the outburst of volcanic 

 products. 



But before entering upon the narrative of events which occu- 

 pied this space of time, let us first endeavour to determine the 

 physical limits of the theatre of these operations ; for it may well 

 be asked, considering the great extent to which the volcanic 

 products have been cleared from off the surface of the country by 

 denudation, with what degree of precision can we define the 

 original limits of the volcanic area ? 



Let us for a moment, when replying to this question, turn to a 

 still more recent volcanic district for an illustration. When we 

 ascend the cone of Vesuvius, and from that commanding station 

 sweep with our eyes the surrounding region, we find ourselves 

 in the centre of a plain — the Campagna of Naples — formed of 

 the products of volcanic eruptions, but limited through three 

 quarters of a circle by calcareous hills of older date, and along 

 the other portion by the sea. 



I believe th?.t similarly, but on a far more extended scale, we 

 can trace out the original limits of the volcanic district of the 

 north-east of Ireland, and that from some elevated stations 

 rising from the central plateau of Antrim these limits may be 

 almost descried by the uprising of ridges of more ancient rocks 

 in several directions. Taking our stand on Tardree Hill, or 

 Sleamish, %ve see to the southward the granitic and schistose 

 ridge of Slieve Croob, projected against a background of the 

 mountains of Mourne, culminating in Slieve Donard. West- 

 ward the eye rests on the rugged masses of Slieve GuUion and 

 the Silurian iiills of Newtown Hamilton. Towards the north, 

 alter passing the depression of the southern shore of Lough 

 Neagh and the valley of the river Blackwater, the enclosing ridge 

 of old rocks, forming from this distance an apparently unbroken 

 line, ranges northward into Donegal and the northern shores of 

 Lough Foyle. The ocean now intervenes ; but a comparison of 

 the physical characters of the Donegal mountains with those of 

 Islay, Jura, Cantyre, and the Western Islands leaves the im- 

 pression on my mind that the volcanic region of Antrim was 

 limited northwards along the line of a submarine ridge, and that 

 there is little reason for supposing that the volcanic rocks of Mull 

 were superficially connected with those of this country, — on the 

 contrary, the probability seems to be that the old crystalline 

 rocks of the Western Highlands were interposed between the 

 two regions. 



Turning to the eastward, the sea overflows an area at one lime 

 occupied by volcanic products, but now only partially so, and we 

 are unable strictly to define their easterly limits ; but it is toler- 

 ably certain that the sheets of lava did not reach the shores of 

 Galloway or those of the Isle of Man. Basaltic dykes, however, 

 as is well known, traverse the north of England and the south of 

 Scotland ; but if referable, as Prof. Geikic concludes, to the 

 Miocene period, they cannot be included in the volcanic region 

 as here described and understood. 



Thus the volcanic plateau of Antrim, like the Campagna of 

 Naples, is washed on one side by the sea, and its limits become 

 indefinable in consequence ; but to the south, the west, and to 

 some extent to the north, the limits of the region are marked out 

 by mountains of considerable elevation. Within this region 

 craters poured forth lavas or other volcanic products, which ex- 

 tended in great sheets until they were intercepted by the uprising 

 of these. natural barriers. 



The door of the area thus partially circumscribed was formed 

 of various materials, as the accidents of denudjitiou admitted. 

 Over the central portions it was chiefly Cretaceous limestone (or 

 Chalk), but to the southward it was New Red Sandstone and 

 Lower Silurian, and to the north. Chalk, Lias, Carboniferous, 

 and Lower Silurian beds in different directions. The whole 

 region composed of rocks thus distributed was probably converted 

 into dry land towards the close of the Eocene period — when, at 

 variorts points, highly silicated felspathic lavas burst forth, con- 

 solidating into sheets of trachyte porphyry, rhyolite, and more 

 rarely pitchstone, such as are found at Brown Dod Hill and 

 Tardree, near Antrim, and west of Hillsborough. These tra- 

 chytic lavas were tlierelore the oldest of the volcanic eruptions of 

 the north of Ireland, and seem to have been represented by the 

 newer gr.mitoid rocks recently described by Zirkcl, Geikie, and 



