G. H. Kinhahan — Nomenclature of the Drift. 547 



whilst the value of the models of it, which have been cut by the best 

 lapidaries, is a mere trifle, that in glass costing but 10s., and that 

 in crystal but £2. The rule given by Jeffries and the best autho- 

 rities upon diamonds for ascertaining the value of cut diamonds, is 

 to multiply the square of the weight in carats by eight, and call 

 it pounds, so that this diamond would, according to this computation, 

 be worth 66 x 66 x 8 = £34,848. 



Fig. 1. 



Fig. 2, Front View. Fig. 3, Side View. Fig. 4, Back View. 



Fig. 1. — Natural Crystal of a Diamond recently found in South Africa. 



Figs. 2-4.— Three views of the same stone after having heen cut as a brilliant by a London 



diamond-cutter. 



VI. — Nomenclature of the Drift. 

 By G. H. Kinahan, M.R.I.A. 



IN the short notice on the Drift (Geol. Mag. July, 1875, p. 328) 

 I did not mean specially to condemn Mr. Birds ; the paper being 

 intended as a general protest against the loose nomenclature used 

 by former writers and adopted by those of the present day. 



As to the Irish gravels, they have never been systematically 

 examined or classed. We have different gravels — 1st, under the 

 25-feet contour-line ; 2nd, under the 110-feet contour-line ; and 

 3rd, under the 350-feet contour-line — all more or less containing 

 marine shells. Although these gravels are of distinct ages, yet the 

 fossils collected from them have been lumped together. Then older 

 than the Esker gravels (under the 350-feet contour-line), there are 

 gravels at about the following respective heights — 550 feet, 750 feet, 

 and 1200 feet, some of which contain fossils, and although these 

 gravels must be much older than the three groups first named, yet 

 their fossils have been all classed together. I remember hearing my 

 brother, the late Dr. Kinahan, remark that the group of fossils from 

 the gravels at Bohernabreena (about 200 feet) were distinct from 

 the group found in the gravels at Howth and the coast to the north- 

 ward (under 100 feet). In no place in Ireland have I seen gravels 

 belonging to the first three groups (the third being the so-called 



