Page:Quarterly Journal of the Geological Society of London, vol. 35.djvu/857

Rh GLENGARIFF GRITS AND SLATES. 717 On the supposition that the beds on the flanks of the Killarney range, amongst which we find the volcanic rocks, are higher up in the series than those at the extremity of the Dingle promontory, it would appear that after the volcanic fires had become extinct in the latter district, they broke out in the region to the south, both r how- ever, belonging to the same geological period. Still later (namely, during the epoch of the Carboniferous limestone) there were fresh outbursts of volcanic forces in the adjoining region of the county of Limerick, resulting in the formation of two distinct bands of lava, the lower augitic, the upper felspathic, and separated by a consider- able interval of time represented by the formation of many feet of limestone. For examples of such intermittent outbursts in the same region in more recent times, we might refer to the volcanic district of Central France, where, along a tract of country extending for some fifty miles, we find a series of several hundred extinct craters, which were in activity at different periods ranging down from the Miocene into the Pliocene, or possibly even later, and where the older erup- tions of Mont Dor and Cantal gave place to those of the Puy and the Vivarais. Plant-remains. — Besides the " fucoid " markings which are com- mon amongst some of the purple-slate beds throughout the moun- tains of Cork and Kerry, impressions of plants, belonging probably to the group of vascular cryptogams, have been found in several places, particularly in the mountains of Iveragh and Dunkerron, by the collectors of the Geological Survey. These have been referred by Mr. Baily to the genus Sagenaria. Tracks also, probably those of Crustacea, have been discovered, of which specimens are pre- served in the collections of the Survey in Dublin. The occurrence of land plants allied to those forms which predominated in the Car- boniferous period cannot be regarded as an argument against the view that the beds containing them are referable to the tipper Silurian period, as several instances of a similar kind have been recognized in North America. In this region plant-remains of the genera Lepi- dodendron, Glyptodendron, and SigiUaria have been found in beds ranging from the base of the Upper Silurian series into the Devonian and Carboniferous *. It is necessary to observe, however, that the specimens of these plants in the collection of the Survey have all the appearance of having been obtained from the Lower Carbonife- rous beds. The rock is fine greyish-blue grit, unlike that which prevails amongst the Glengariff beds. In either case the occurrence of plants does not, as it seems to mo, affect the question of the age of these beds f. quereux, Prof. Claypole, and others, and are cited by the last-named observer, in a paper recording a fresh discovery, in Geol. Mag., Dec. 1878. t Since the above was written, the spol shave been re-examined by Mr. Baily, and there seems little doubt of the occurrence of the plants in the Glengariff beds. Q. J.G.S. No. 140. 3 c
 * These have been mentioned by Dr. Dawson, Prof. James Hall, Prof. Les-