S. Ifyde — Deep-mining in the South-west of Ireland. 243 



tlylcG of gi-ooiistono (Diorifo) runs north and south in the cliff to the 

 west of this vein, and at right angles to the course of the lodo. 



Other extonsivo mining operations succeeded and have been con- 

 tinued down to the present date under the name of the " Boarhaven 

 Mines," and with varying rcsiilts, and on the "mountain and 

 caminches lodes," levels have been driven deep. The Caminches 

 lode strikes north-north-west, with an underlie to the soutli-east; a 

 cross-course seems to have cut off this lode along its strike to the 

 north. In 1860 more than 1,000 hands wore employed in the 

 Bearhaven and Alliliies mines. 



It will be seen then that the mineral bearing rocks of the south- 

 west of Ireland occur near or towards the upper part of the loiver 

 division of the Old Eed Sandstone, or base of the Upper Old Eed. 

 Cornstones or calcareous bands occur throughout the whole series, and 

 these, Avhen impregnated with, or containing copper, are locally called 

 " Gosseu lodes." It is believed that the thickness of the Old Eed 

 Sandstone is between 2,000 and 3,000 feet, although the base 

 nowhere ajDpears to be exposed in this area; the upper 800 feet, 

 according to the Geological Survey of Ireland, being called the 

 Upper Old Eed Sandstone.^ 



A series of anticlinal and synclinal curves occur in this region, 

 the chief of which is that which traverses Ballydebob, Skull, Toor- 

 more Bay, and Crookhaven, &c. The axes of the Ballydebob 

 anticlinal strikes east 25^ north, with a general dip to the north- 

 west of about 50*^, and to the south-east 45°, and it is along this 

 that the highest land occurs, being mainly composed of slates and 

 gritty beds of the upper part of the lower Old Eed Sandstone. South 

 of this, between Cappagh Lodge and Skull Harbour, and close to 

 Eossbrin Cove, are situated the extensive and deep copper mines of 

 Ballycummisk, and on the east side of Skull Harbour occurs Coos- 

 keen mine, the geological position and mineral conditions of which 

 form the subject of this communication. 



The object of this notice is to bring before this Society and men 

 of science the maia features of, and high importance attached to, 

 the solution of the problem of deep and continuous mining opera- 

 tions throughout the south and south-west of Ireland, and to 

 endeavour to parallel the mineral conditions of the south o*f Ireland 

 with those of Cornwall, although it is well known that the granitic 

 and other igneous rocks of the Cornish Promontory have not 

 been determined south of Carlow and Waterford ; except near 

 Mangerton, immediately south of Killarney, where the felspathic 

 greenstones constitute very insignificant features in the physical 

 structure of the country. 



We cannot but regard the south of Ireland as a continuous and 

 integral portion of the south-west of England, and south Wales, the 

 variations in rock masses being such as are due either to local 

 conditions and causes at the time of deposition ; or, probably still 



1 Mem. Geol. Survey. Explanation to accompany slieets 200-3-4-5 of maps of the 

 Geological Survey of Ireland, County Cork. 



