538 eeport— 1878. 



many towns in Ulster. In too many cases the present supplies were derived from 

 the uncertain and dangerous sources of shallow-surface wells, situated within the 

 habitable area — sources universally condemned as scarcely possible to be free from 

 pollution. 



The two great systems of water supply were contrasted — that by catchment 

 basins with reservoirs, and that by deep wells or borings. The author strongly 

 advocated the latter, where geological formations would warrant a trial. He 

 showed that many towns in England were successfully supplied by artesian wells 

 i >r borings into the Chalk or New Red Sandstone formations. 



The rocks of Ulster were then reviewed with . special reference to their 

 suitability for rendering water by boring, and the best localities for such operations 

 enumerated. 



Among the formations which did not possess the essential conditions necessary for 

 success were mentioned the Lower Silurian rocks which comprise the greater portion 

 of the counties of Down, Louth, Armagh, and Monaghan, and the granitic tracts of 

 Newry, Slieve Croob and Mourne, in which localities the catchment basin system 

 had to be adopted, as was the case for the Newry water supply. 



In the same category were placed the granitic and metamorphic tracts of Done- 

 gal and West Londonderry. 



The New Red Sandstone — in England one of the chief formations in which to 

 bore for water- — occupies in Ulster a very limited surface area, being for the greater 

 part overlaid by other formations. Artesian borings in these rocks had proved 

 successful, as at the " Cromac Springs " in Belfast, while in other cases they had 

 been unsuccessful, from a wrong selection of sites. 



The Chalk and Hibernian Greensand formations were shown to be the great 

 water-bearing strata of Ulster, occupying a very extensive area in the counties of 

 Antrim and Londonderry, but overlaid by other formations, such as the Tertiary 

 basalts. . The Mesozoic rocks form a geological basin, the basaltic area occupying 

 the centre, with the Chalk and Greensand cropping out almost continuously along 

 its margin, and underlaid by the plastic clays of the Lias or Keuper marls. The 

 occurrence of this basin was clearly demonstrated by the elevations and dip of the 

 chalk around its margin, and its deep-seated existence inside, as at Templepatrick 

 and other places. The presence of large quantities of water in the Cretaceous beds 

 was apparent everywhere, from the number of large springs along the outcrop, and 

 the constant outpouring of water where the lip of the basin was low, resulting 

 in frequent landslips, as at Garron Tower, Carnlough, Glenarm, Whitehead and 

 other places. 



The existence of water held under hydrostatic pressure within the basin was. 

 also evidenced by the numerous large perennial springs occurring in the basaltic 

 plateau. 



The sequence of the formations within this area and the occurrence of water- 

 bearing strata were then enumerated. Below the so-called upper basalt there 

 exists the first great water-bearing stratum at the ferruginous lithomarge bed of 

 the iron-ore measures. For potable purposes it is too highly charged with hydrated 

 oxide of iron. The lower aluminous bed is also water producing, of a purer 

 quality, but less plentiful ; the districts where these occur are, however, compara- 

 tively small. 



By boring through the overlying basalt within this extensive basin the chalk 

 and greensand could readily be pierced— if within the area of the lower basalt, at 

 no great depth — and where, undoubtedly, a plentiful and pure supply of water 

 would be obtained. 



The districts where such, with every prospect of success, might be attempted 

 would be approximately along the valley of the river Bann, or near Ballymena, 

 Ballymoney, Coleraine or Antrim. The districts of Cookstown, Dungannon and 

 Moneyniore were differently situated geologically, but the formations were favour- 

 able, and water had been proved in the bore-holes for iron ore in that neigh- 

 bourhood. 



The author strongly advocated, for certain localities in Ulster, the adoption of 

 deep wells or borings for the purpose of obtaining water supplies. 



