. Manual of the geology of Ireland. thesame type as the Mount Fathom elvan. Coming up through the Barnavave elvan, and appa-rently much newer than it, are dykes and protrusions of aspotted eurite or toadstone, while these later rocks are cutup and traversed by dykes of dolerite and basalt, ingeneral very like the Miocene dolerites of Antrim. Inplaces, however, the dykes of dolerite graduate into thespotted eurite, while the latter, when in wide dykes or inprotrusions, merge into a granitoid rock or spotted latter rock is of a bluish colour, spotted over withcrystalline spheroids of w
. Manual of the geology of Ireland. thesame type as the Mount Fathom elvan. Coming up through the Barnavave elvan, and appa-rently much newer than it, are dykes and protrusions of aspotted eurite or toadstone, while these later rocks are cutup and traversed by dykes of dolerite and basalt, ingeneral very like the Miocene dolerites of Antrim. Inplaces, however, the dykes of dolerite graduate into thespotted eurite, while the latter, when in wide dykes or inprotrusions, merge into a granitoid rock or spotted latter rock is of a bluish colour, spotted over withcrystalline spheroids of whitish felspar, being identical inappearance with the margins of the large course of elvanat Goragh-wood station, now extensively quarried underthe name of the Goragh-wood granite. This elvancourse comes up through the Newry granite, and evidentlyis much newer than it; and at its margin is the rocksimilar to the spotted elvan of the Carlingford promon-tory, all being of the same age, which is probably Mio-cene. Eruptive Rocks. 211. o P 2 212 Geology of Ireland. It has been shown that farther northward, in the pro-vince of Ulster, there are interbedded pyroxenic rocks ofboth Triassic and Miocene ages, the later being much moredeveloped than the older. Carlingford Lough Districtseems to have been a centre of vulcanicity during theMesozoic and Cainozoic periods, or perhaps even earlier,the eruptive rocks in it being of different ages ; it is there-fore probable that the pyroxenic rocks of Triassic, as wellas those of Miocene age, have their representatives. Thedykes are exceedingly numerous, as seen in the Carboni-ferous quarries in the neighbourhood of Carlingford. In reference to the anorthite-syenite of Haughtonmentioned in page 209, Traill states, this rock en massewould be more appropriately called Gabbro, graduatingon the one hand into hypersthene-dolerite or hyperite, andon the other into diorite ; as the pyroxenic mineral changesfrom diallage, either into hypersthene or in
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