THE 



GEOLOGICAL MAGAZINE. 



NEW SERIES. DECADE II. VOL. I. 



No. v.— MAY, 1874. 



I. — The Elevated Shell-bearing Gravels neae Dublin. 

 By the Eev. Maxwell Close, M.A. F.G.S.i 



r"nHE elevated Drift deposits near Dublin have been brought 

 I under the notice of the Society by other observers. The late Mr. 

 John Kelly has described in our Journal (vol. vi. p. 133) part 

 of the gravels which form the subject of this paper ; including 

 the collection at Caldbeck Castle, 1300 feet above the sea. I 

 have already mentioned before the Society (in 1867) the fact of 

 having found marine shells in the Pleistocene gravels near Dublin, 

 at heights of 1000 and 1200 feet above the present sea-level ; ^ 

 but I did not wish to offer a paper on the subject until I had 

 collected what might seem sufficient materials for one. These shells 

 are not only in a very fi-agmentary condition, but also scarce, so 

 that they easily escape notice ; and it is necessary to pay several 

 visits, at sufficient intervals, to the few places where the shells are 

 accessible, in order to obtain from thence even a limited collection 

 of determinable species. 



The gravels now in question belong to the " limestone gravel " 

 of Ireland, and occur on the sides, or in the immediate vicinity, of 

 the hill mass, the best known of whose prominences is named the 

 Three-Eock Mountain — part of the N.E. end of the Wexford, Wick- 

 low, and Dublin granite range. Ballyedmonduff is on the S.E. side 

 thereof, on the road leading from Stepaside to Glencullen. A little 

 below, and N. of, the highest point of that road, on the E. side of 

 the road, just opposite Ballyedmonduff House, and at the elevation 

 of just 1000 feet, is a gravel-pit which has yielded the shells given 

 below. The distinctly-shaped mound, or mamelon, in which the 

 pit is dug, is chiefly composed of clean stratified gravel and sand ; 

 it is part of a great collection of Drift which extends into the S.E., 

 or Ballyedmonduif, bosom of the above-mentioned hill mass, and 

 over the slight col at the highest point of the road leading to Glen- 

 cullen ; at which latter place it (the gravel) is of very considerable 

 depth. In the said bosom the gravel maintains, at its upper edge, 



^ Eead before the Eoyal Geological Society of Ireland. 



'^ These are noticed in Jukes's "Manual of Geology, edited by Prof. Geikie ; by 

 Prof. Ilarkness in the Geological Magazine. Vol. VI. p. 545 , and in Sir 0. Lyell'is 

 "Student's Elements of Geology," where, however, they are placed in the Co. 

 Wexford, and in the Pliocene formation. 



decade II. — VOL. 1. — NO. V. 13 



