Page:Quarterly Journal of the Geological Society of London, vol. 26.djvu/254

152 nature and geognostic relations of the iron-ores associated with the basalts, and the present seems a fitting occasion to submit to the Geological Society the results of our observations.

The occurrence of ferruginous ochres in the midst of the basalt of the Giant's Causeway was pointed out at an early period by the Rev. Dr. Hamilton, and has been noticed by subsequent writers on the geology of the County Antrim. Dr. Hamilton, in his section of the Pleaskin, represents "a thin course of iron-ore amid a bed of ochre;" and it is to beds of this character that we would now direct attention; for beyond the mere record of the occurrence of an iron band in the basalt of the Giant's Causeway, no further account of this phenomenon has been brought before the notice of geologists.

The railway-cutting at Ballypalidy, near Templepatrick, exposed an extensive ochreous mass, the working of which was commenced by Dr. Ritchie, of Belfast, in 1861; but within the last three years new and richer deposits have been discovered and worked in other parts of the county. A list of the localities where operations are now carried on will be found appended. Shortly after the discovery of the ferruginous beds at Ballypalidy, our attention was directed to the nature of the ore there; and in the spring of 1868 one of us communicated to the Belfast Naturalists' Field Club an abstract of this paper in part, which is published in that Society's Proceedings for that year.

We may be allowed to state that the examination of these iron- ores, the subject of the present communication, has been undertaken solely in the interest of science. And we would record our obligations to the Earl of Antrim, Dr. Ritchie, and Mr. T. Fisher for permission to inspect the mines respectively worked by them, and for statistics of produce relating to the same, also to Dr. Apjohn and Professor Hodges for analyses of basalt and iron-ores.

As regards the origin of their present condition, the iron-ores may be divided into two groups; to the one belongs the ore of Ballypalidy, whilst all the others known to us are included in the second group. The former is of sedimentary origin, but the latter are the direct products of metamorphic agencies.

As a remarkable similarity is exhibited by all the sections of the iron-ores of the second group and their associated rock-masses, it will be unnecessary to describe each of them; we select, therefore, for illustration the following, which are the most instructive of the series.

1. Section on Slievananee.—On the south slope of Slievananee mountain, situated 6 miles from Cushendall, on the road to Ballymena, a rich mine of iron-ore was opened three years ago beneath the basalt, at an elevation of 1095 feet above the sea, and 687 feet vertically below the summit of the mountain. The present face of the workings presents a horizontal section of nearly half a mile; the