LOUTH GEOLOGY

The geology of this portion of the island is very simple. The Ravensdale and Carlingford mountains, in the north, are dependent on the Mourne mountains, and, like them, are composed chiefly of granite. Hornblende and primitive greenstone abound on the skirts of this granitic district, and to these succeed exterior chains of transition rocks. The rest of the county is chiefly occupied by clay-slate, except where limestone occurs in detached districts, as in the neighbourhood of Ardee, Killyner, and Mell. An extensive limestone field stretches from Shanlis towards Louth; another rises very abruptly near Collon. Blue limestone occurs near Carnabeg and Killin.

Near Castletown there is a very pure red limestone, which appears to be the southern termination of the Armagh field; none other of the same character having been found anywhere except at Castle-espie, in Down county. Other detached beds of this rock are worked in various parts of the country for agricultural purposes and for building. The line of demarcation between the granite and transition rocks is very clearly defined. Commencing at Carlingford, it crosses the Ravensdale and Cooley mountains and enters Armagh county at Myra Castle, whence it is traceable into the mountains of Forkhill: the new red sandstone is to be perceived only in a few places.

Lead ore has been found in thin veins near the junction of the granite and transition rocks; and detached nodules have been found near Ardee, and in the bed of the Flurry river. Oxyde of manganese and impure ironstone have been discovered near Clogher head, and iron pyrites near Mount Ash and Ring Castle. The remains of iron-works are often found on the hills.

The manufacture of sheetings and other kinds of coarser linen cloth is carried on in the neighbourhood of Drogheda to a considerable extent, arid there are large bleach-greens at Ravensdale and Collon. A pin-manufactory, established in Dundalk in 1836, gives employment to upwards of 600 persons; another of the same description is in course of erection in the town of Louth. There is an iron and brass foundry in the former of those towns, the castings of which are held in high estimation.

At Dundalk and some other places there are extensive distilleries and breweries: the character of the ale of Castle-Bellingham has long stood very high. Flax-mills are to be seen on all the smaller rivers, and there are several large and very powerful flour and meal mills throughout the county. There are three places of export for the agricultural and manufacturing produce, Newry in the north, Drogheda in the south, and Dundalk midway between the two; but the trade of the last-named place is somewhat impeded by the shallowness of the harbour, which prevents vessels of large burden coming up to the quay, except at spring tides.

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