196 The Irish Naturalist. July, 



DUBLIN NATURALISTS' FIELD CLUB. 



May 30.— Excursion to MontpeIvIER.— Fifteeu members and 

 visitors were present. Tlie start by car and cycle from Terenure was 

 made under most unpromising conditions of weather, rain coming down 

 in torrents at the appointed hour of departure. Matters soon improved, 

 however, and fortunately the rain kept off for the rest of the day. 



On the wa}' to Rockbrook, where the party was met b}- the conductor, 

 Professor Cole, the post-glacial river terraces of the valley, now grass- 

 covered, w^ere conspicuous. The party then walked from Rock- 

 brook to the base of Moutpelier Hill. Near Mount Venus an exposure 

 of the central granite of the Leinster chain was noted in the roadway, 

 and a little further on beyond the junction, which is not exposed here, 

 the uptilted Silurian schists, with intruding veins of granite, were seen. 

 Ascending the hill, which is formed of these schists, but which retains 

 a cap of gravel, the change in the character of the vegetation was soon 

 apparent, the rich fields on the Boulder-clay below giving place to the plant 

 associations in which the gorse and heather predominated on the poor 

 soil derived from the schists. The gravel cap, however, seems to bring 

 in the grass type once more, and from a pit just south-east of the summit 

 the great masses of drift banked up against the hills, and the contrast 

 between the vegetation on this and on the almost bare granite of the 

 hills themselves, was very well seen. 



Professor Cole here took the opportunity of explaining how this great 

 mass of drift, made up of materials melted out of the great ice sheet, with 

 the addition, notably in the upper layers, of local granite boulders, and 

 reaching at the head of Kelly's Glen, a height of 1,250 feet, had been 

 deposited. The party were then fortunate in being joined by Mr. G. W. 

 Lamplugh, who had at some personal inconvenience left Belfast earlier 

 in the day in order to be present at the excursion. After a brief interval 

 for lunch, a descent was made into the Dry Gap, where Mr. Ivamplugh 

 explained its characteristics and its probable mode of origin. During 

 the glacial period the land ice probably closed up the outlet of the pre- 

 glacial valley of Glenasmole, and when the snows and ice melted this 

 valley became a lake, the waters of which were dammed up sufficiently 

 high to find an outlet over the eastern wall of the valley, choosing the 

 lowest notch, the outflowing volume of water speedily caused a rapid 

 denudation, thus producing the present steep-sided ravine, which subse- 

 quent slower weathering has converted into a pass with the highest point 

 in the middle. 



Leaving the gap, the party walked on to the bogg}' ground above 

 Piperstown, where the xerophytic characters of several of the predomi- 

 nant plants were discussed. Butterworts and Sundews were found, as well 

 as one example of the rather uncommon orchid Listera cordata. The 

 party then returned by road to Rockbrook for tea, passing through 

 a part of Cruagh Wood, a well-known gravel pit at 800 feet, and the great 

 masses of gravel through which the Rockbrook stream cuts being noted 

 en route. The prize offered by Dr. Pethybridge for the best account of 

 the excursion, has been awarded to Mr, F. O'B. Ellison. 



