ixiY INTBOD UCTION. 



northwesterly direction it enters Lough Neagh at the southern extremity 

 of the lake, which it leaves at Toome on the north. From hence its course 

 is nearly due north, separating the counties of Antrim and Deny, and 

 ultimately falling into the sea near Coleraine. The Lagan has its source 

 in the Slieve Croob Mountains, at no great distance from the source of 

 the Bann. It takes a very circuitous course, first to the west, then curv- 

 ing round to the north and east empties itself into Belfast Bay, after 

 having passed the to^Tis of Dromore, Lisbum, and Belfast. The flow of 

 the river is thus nearly 40 miles, though the distance accomplished is no 

 more than 20 miles in a line direct. The Foyle is formed at Lifford, 

 in the county of Donegal, by the imion of several smaller streams. 

 Flowing nearly due north, and dividing the coimties of Derry and 

 Donegal, it enters Lough Foyle at Culmore, after a course of over 20 

 miles. If traced, however, to its tdtimate head this river would appear 

 much more extensive, a great portion of its waters being collected in 

 Tyrone and Donegal. In addition to these tidal rivers there are many 

 others of considerable note ; the district being exceptionally well watered, 

 and its flora enriched by a number of interesting fluvial plants. Many 

 small lakes are scattered over the coimtry, and Lough Neagh, the largest 

 British lake, enters into the district, the greater part of its waters being 

 within the bounds of Antrim and Derry. 



GEOLOGY. -The counties of Down, Antrim, and Derry are widely 

 dissimilar in their geological structure, the two former especially offering 

 strong contrasts, not only in the age of the rocks, but also in their 

 chemical and petrological characters. Derry, while conforming to 

 neither, is, nevertheless, made up to some extent of rocks such as occur 

 in Down and Antrim, with the addition of others which are not at all, or 

 only slightly developed in those counties. The county of Down has a 

 totally difl'erent geological history, and a rock series quite distinct from 

 that of Antrim. The masses of dark coloured rocks that prevail over the 

 greater part of Down have siiffered many vicissitudes since they were 

 deposited in Lower Silurian times ; though they seem to have remained 

 mostly above water from the epoch of their elevation. Indurated, shattered, 

 and contorted, the originally horizontal beds are now found inclined at 

 high angles, sometimes vertical, and in other cases turned over and 

 inverted. These old rocks consist of gray and black slates, too coarse to 

 be of much economic value, and hard, massive, intractible grits. They 

 never rise to a high altitude, and seldom present much of picturesque 

 beauty, nor do they yield a flora so rich and varied as that found on the 

 basaltic rocks of Antrim. This poverty is, however, compensated in 

 some degree by the granite mountains of the Moume range, which supply 

 rocks of much industrial importance, and also habitats for many of the 

 rarer plants. Stretching southwest, from Newcastle to Rostrevor, they 

 form one of the most majestic groups in Ireland. A small strip of Triassic 

 sandstone occurs close to Newtownards, and thence to near Dundonald, 

 ftnd unimportant patches of C^bpniferpus limestone appear on the shpr§§ 



