PROCEEDINGS 



OF 



THE GEOLOGICAL SOCIETY OF LONDON. 



Vol. II. 1836-1837. No. 48. 



November 30. — Charles Darwin, Esq., A.B., Christ's College, 

 Cambridge ; Thomas White Collard, Esq., of Prospect House, near 

 Heme, Kent; Rev. John Pye Smith, D.D., of Homerton College, 

 near London ; William Cubitt, Esq., of Gray's Inn Lane ; and Wil- 

 liam Railton, Esq.j of Carlton Chambers, were elected Fellows of this 

 Society. 



A paper "On certain elevated Hills of Gravel containing Marine 

 Shells in the vicinityof Dublin," by John Scouler, M D., F.L.S., Pro- 

 fessor of ^'iineralogy in the Royal Dublin Society, and communicated 

 by Robert Hutton Esq., F.G.S., was first read. 



The object of this communication is to give a brief account of phe- 

 nomena which, although frequently described in other countries, have 

 been but recently observed in Ireland. Before entering on the im- 

 mediate subject ol the paper, Dr. Scouler gives a general description 

 of the formations constituting the district under examination. They 

 consist of granite, porphyry, quartz rock, micaceous, talcose, and 

 argillaceous schists, gieywacke, which near Lyons is succeeded by a 

 very ferruginous conglomerate, and mountain limestone, called, near 

 Dublin, calp. 



The principal points at which the author examined the shelly de- 

 posits are, the promontory of Howth, Bray Head, and the valley of 

 Glenismaule. On the south side of the promontory of Howth, where 

 the limestone or calp approaches the quartz rock, is a deep depression 

 occupied by an exceedingly tenacious and very ferruginous clay, which 

 also extends across the peninsula, filling up fissures in the limestone. 

 It is unstratified, and does not contain any transported fragments of 

 rocks, but abounds with nodules of oxide of iron, iron pyrites, and 

 oxide of manganese ; the last being extracted for economical pur- 

 poses. Resting upon this clay, the limestone and the quartz rock, 

 is a thick accumulation of shelly coarse gravel and fine sand, extend- 

 ing about half a mile in length, but separated into two parts by the 

 hollow in which is situated the village of Howth. The highest portion 

 of the deposit is about eighty feet above the level of the sea. The 

 gravel consists chiefly of limestone, differing in no respect froni 

 the limestone of the district ; pebbles of argillaceous schist are not 

 uncommon ; and rounded fragments of granite, the hard chalk of An- 

 trim, and flints occur, but rarely ; and it is worthy of remark that 

 though the gravel rests partly on quartz rock, fragments derived from 

 it are scarce. 



The beds of sand are sometimes very thin, at others of considerable 



VOL. II. 2 I 



