Geological Survey of Ireland. 319 



II. — Geological Survey of Ireland. 



1. Explanatory Memoir to accompany Sheets 104 and 113, with 



the adjoining portions of Sheets 103 and 122 (Kilkieran and 

 Aran Sheets). By G. H. Kinahan, M.E.I. A., H. Leonard, 

 M.E.I. A., and E. J. Cruise, M.E.I. A. 8vo. Dublin, 1871. 

 pp. 92. 



2. Explanatory Memoir to accompany Sheets 86, 87, 88, and 



Eastern part of 85. By G. H. Kinahan, M.E.I.A., and E. G. 

 Symes, F.G.S. ; with Palseontological Notes by W. H. Bailt, 

 F.L.S., F.G.S. 8vo. Dublin, 1871. pp. 63. 



THE first Memoir is taken up with a description of the Aran 

 Islands, and portions of the mainland of Galway contained in 

 the maps enumerated. The mainland, which possesses no town, is 

 intersected by numerous chains of lakes, bays, and creeks. The 

 land is low, averaging from 200 to 500 feet in elevation. From the 

 north-east shores of the Aran Islands the land rises in a series of 

 cliffs or huge steps, which form continuous terraces ; while from the 

 summit of Inishmore, one of the islands, there is a gradual fall 

 south-westward, ending at the sea- board, in cliffs now being formed 

 by the Atlantic Ocean. 



The formations met with include : — Bog and Alluvium, Glacial 

 Deposits, Carboniferous Limestone, Granitic and Igneous Eocks. 

 The Granites are of two classes^ the intrusive, and those of ap- 

 parently metamorphic origin. 



The lithological character of these rocks is treated of at length : 

 the authors then pass on to the relations between the form of the 

 ground and its internal structure. The Aran Islands are composed 

 of limestones, with thin shales and clay interstratified, and to the 

 effects of denudation on them is due the terraced-form they now 

 possess. In the metamorphic rock country are peaks and knolls 

 composed of hornblende rock. The action of ice is very con- 

 spicuous in this district ; a table of supposed ice stri« is given. 



For convenience of description the area is divided into five sub- 

 districts, and these are described in detail. 



Of the drifts, there is a local boulder or moraine drift, consisting 

 of a sandy or clayey mass, full of small and large fragments of 

 local rock, often several tons in weight. 



The Bogs are of two kinds, the low-lying, flat, or peat bogs, 

 which are often of considerable depth, and the mountain bogs that 

 frequently grow on steep slopes. 



Some of the low bogs are most deceptive, being seemingly a solid 

 surface, but having water or mud underneath; and, as they are 

 clothed with vegetation in the spring, they are very dangerous to 

 cattle. At this season, when grass is scarce, the cattle, and especially 

 horses, are tempted to venture on them, when they go down bodily, 

 and often only the heads of the horses remain uncovered. The 

 authors think in this way to account for the skeletons of the Mega- 

 ceros Ribernicus being so frequently found in small isolated bogs, 



