474 Proc B.N.F.C., 



Newcastle in the distance nestling at the foot of Slieve Donard, 

 of the Mourne range, which rises neaily 3,000 feet above it. 



There is a well marked difference between the surface geo- 

 logy of this bay south of St. John's Point and the surface 

 geology of the shore to the north of St. John's Point to 

 Killough. The Bay of Dundrum has for the most part a flat 

 sandy shore backed by extensive sand dunes which extend for 

 a distance of six miles around the shore, and at low water 

 great stretches of flat sandy surfaces are exposed ; whereas 

 from St. John's Point to Killough the shore is composed of the 

 serrated edges of tilted rocks in the wildest confusion and of 

 the grandest aspect, the result of volcanic forces that operated 

 ages ago upon elementary rocks, several thousands of feet thick, 

 once horizontal layers, but now tilted up on edge, so that the 

 geologist can read the marvellous records indicated by the ex- 

 posed strata. Here are thin layers of fine strata laid down in 

 deep still water ; here are the rougher grits of ancient shore 

 lines, and their upturned edges are now cut through in all 

 directions by varied forms of once-molten volcanic matter that 

 now stand out as dykes throughout the district. A rich 

 variety of rock specimens was secured here, and our marine 

 zoologists made good use of the favourable opportunity afforded 

 them in the rents, fissures, and rock pools that abound along 

 this sea-beaten coast, where, in an apparent wilderness of geo- 

 logical confusion, the earnest naturalist can detect even the 

 minute forms of organic life. One member provided with 

 waterproof sea-boots waded into the rock pools, and his cap- 

 tures were considered most satisfactory. Many of the 

 pools below high water were found well stocked with an 

 abundance of interesting forms. The ridged periwinkle that 

 assumes such a variety of colours was found very numerous, 

 and some four species of isopods, with a great variety of other 

 forms, were collected. Coming towards the land, Helix nemor- 

 alis, a thin form, was taken close to the beach. Farther inland 

 Vertigo anlivertigo and two other species of vertigo were found 

 in abundance around the flax pools, with Aplexa hypnorum and 

 Planorbis sbirorbis, &c. 



