No. III.

ABSTRACT OF THE TREASURER'S ACCOUNT FOR THE YEAR 1855.

42538

Mr. Oldham's do. for Engraving,

(per Draft 5137)

11 10 0

Mr. Tallon, for Stationery,

0

Incidentals, per Assistant Secretary,

6 10

4

(per Draft 5143),

Collector's Commission,

11 9 4

Incidentals, per Assistant Secretary,

5 11

39 3

(per Draft 5144),

9 1 0

The Report having been read and adopted, the Ballot was closed, and the following Officers and Council declared duly and unanimously elected.

President:

LORD TALBOT DE MALAHIDE.

Vice-Presidents:

JAMES APJOHN, M. D.

PROFESSOR HARVEY, M. D.

JOSEPH BEETE JUKES, M. A.

REV. HUMPHREY LLOYD, D. D.
RICHARD GRIFFITH, LL. D.

Treasurers:

SAMUEL DOWNING, C. E.

GILBERT SANDERS, ESQ.

Secretaries:

REV. PROFESSOR HAUGHTON, F. T. C. D.

FREDERICK J. SIDNEY, LL. D.

Council:

ROBERT BALL, LL. D.

JOHN MACDONNELL, M. D.

ROBERT CALLWELL, ESQ.

ROBERT MALLET, C. E.

REV. J. A. GALBRAITH, F. T. C. D.

JOHN KELLY, ESQ.

GEORGE M'DOWELL, F. T. C. D.

EDWARD WRIGHT, LL. D.

RICHARD PURDY ALLEN, ESQ.

REV. GEORGE LONGFIELD, F. T. C. D.

SAMUEL GORDON, M. D.

JOHN B. DOYLE, ESQ.

THOMAS HUTTON, ESQ.

DOMINICK M'CAUSLAND, M. A.

WALTER S. WILLSON, ESQ.

THE Society met on the 9th of January, 1856, on which occasion the following Paper was read.

ON THE GEOLOGY OF THE LAKE DISTRICT OF KILLARNEY.

BY MR. GEO. V. DU NOYER.

THE district to be described comprises in superficial extent an area of about 100 square miles, inclusive of the Lakes; and is marked on the Ordnance Survey Index of the county of Kerry as sheets 65; southern half, 66, 73, 74; and the northern halves of 83, 84. It will be seen, therefore, that Carrantwohill Mount, Macgillicuddy's Reeks, and the Black Valley, the Range of Knocknabreda, with Cromagloun and Torc Mountains, the rocky ridge terminating in the Eagle's Nest, Cliff, Mangerton, and the Devil's Punch-bowl, are included in this area.

As he proposed noticing the rocks in descending order, he had first to speak of

THE COAL-MEASURES.

These occupy but a small portion of the district, and constitute its northern boundary, forming the low ridge of ground on which the old church of Aghadoe stands. They consist of thick beds of dark gray, splintery shale, often almost black, and sometimes presenting a concretionary structure. Through these shales are thick and thin bands, and often sets of beds of hard gray and olive gray grits, in the thinner layers of which, impressions of coal plants are not uncommon. The only point of present geological interest connected with these coal-measures is the fact, that wherever they can be well observed along their southern boundary, they invariably dip to the south from 30° to 65°,—thus appearing to underlie the Carboniferous Limestones. As this discrepancy in the dip is persistent for many miles from the west of Killarney to Mallow, a distance of fully 50 miles, it can only be accounted for by supposing either a fault, or an inversion of the beds by contortion.

CARBONIFEROUS LIMESTONES.

In Muckross Demesne occurs the most perfect development of the Carboniferous Limestones of the Killarney district. The uppermost beds there, or those which occur in the eastern portion of the Demesne, are all of a light gray colour, close-grained and finely laminated, a structure apparently in many instances due to cleavage;

but where the bedding is at all discernible, it dips southward from 35° to 40°; where the cleavage prevails, its inclination and strike coincide with those of the beds. Fossils are sparingly scattered through these limestones, and consist chiefly of crinoid fragments. As we proceed westward, dark gray chert sometimes occurs in irregular and thin lumpy layers, but generally the rock is homogeneous in character. Below the beds just described are others which are finely crystalline, with numerous hard, irregular, semi-calcareous layers, weathering out like chert. These siliceous beds are well seen on the western shore of Dundag Bay, close to Muckross Abbey, the seat of Colonel Arthur Herbert; they also dip southward at 60° to 70°, and may probably be about 200 feet in thickness. The same beds cross the entrance to Kilbeg Bay; and close to the Devil's Island they are contorted in such a manner as to indicate the presence of a fault, which he named the Doo Lough fault.

Immediately below these siliceous beds, light gray laminated limestones again occur, similar in character to those first described, and traceable along the shore of Mine Paddock Bay still farther to the west, dipping south at 40°, and presenting a thickness of about 300 feet.

At the northern extremity of Mine Paddock Bay a remarkable set of beds are now observed. These are best seen at the "Marble Quarries" west of the bay, and consist, first, of thin lenticular layers of white, pink, and greenish compact marble, with numerous irregular laminæ of green and purple argillaceous shale, not calcareous. Second, light-gray compact marble, in very thin layers, with light green argillaceous shale partings, the average dip of all being southwards at 30°, with a thickness of about 50 feet. These beds are totally devoid of fossils. Below these marble layers the limestone becomes gray and finely crystalline, with chert layers arranged closely together. As we descend in the series, the chert dies out; and along the shore east of the old copper mine the limestone becomes decidedly crystalline and fossiliferous, rather regularly bedded, and the chert occurs sparingly in nodules. About 500 feet west of the beds last described, the old copper mine occurs; it appears as occupying a break in the limestones, striking E. N. E. from the shore, where it is filled with decomposed iron pyrites. Fragments of copper pyrites lie scattered about, and many of these, when broken, exhibit strings of galena. West of the lode the limestones become thin

bedded, dark gray, finely crystalline, and occasionally compact with crinoid fragments and other fossils; and these beds rapidly graduate down into the Carboniferous Slate, as we proceed still further to the west.

If therefore we take the thickness of the limestone, from the top of the first siliceous beds observed at Dundag Bay to the top of the Carboniferous Slates, we have a total amount of 800 feet; this does not include the upper beds to the east in Muckross Demesne, the thickness of which is nowhere ascertainable. At the entrance to Coolough Bay, west of the copper mine, the Carboniferous Slates are well seen. They average about 250 feet in thickness, and dip southwards at 40°. In general character they consist of dark gray slate beds, with a few thin crystalline limestones, thin gray grits, and gritty slate layers, all more or less fossiliferous. The most common fossils are:-Orthis filiaria, Strophomena crenistria, Spirifer disjunctus, Athyris planosulcata, Fenestella plebeia, and stems of Actinocrinus. At the base of the section, and resting on the upper Old Red, there is a set of thin gray grit layers and gritty slates, almost devoid of fossils, and probably occupying the position of certain well-marked beds in the Bantry Bay section, termed by Mr. Jukes, Comhola grits.

From Coolough Bay the Carboniferous Slates strike westerly, with the same dip as last observed, till they cross over from Muckross Peninsula (south of Brickeen Bridge), on to Brickeen Island, where they, as well as the upper Old Red beds, are cut off abruptly by a N. and S. fault, which he named the Brickeen Island fault; and here the Carboniferous Slates and Limestones of Muckross terminate to the west.

Returning now to the marble quarries, and taking those peculiar beds as a well-marked geological horizon, they can be traced eastwards for the distance of 1200 feet, when they abut against the Doo Lough fault, and are shifted northwards about 250 feet by the fault which is a downcast to the N. E.; where the line of this fault crosses the gray compact limestone, underlying the marble layers, the former is changed to a light brown dolomite. He remarked that the Doo Lough fault had a probable strike of N. 55° W., traversing obliquely across Muckross Peninsula from the small promontory on the south close to the Devil's Island, right through the centre of Doo Lough, and from thence into the small rocky inlet west of Ardnagluggen Point, on the north shore of Muckross.