Reports and Proceedings — Geological Society of London. 237 



Mechanical analyses of the clays are given ; but the point of 

 greatest interest is the occurrence of abundance of Foramiuifera, 

 especially in the plastic brown and red Boulder-clays, which 

 often contain intensely striated erratics. These Foraminifera have 

 been examined by Mr. Joseph Wright. Most of them occur in the 

 Boulder-clays of Crosby and Wirral ; but some of them are very 

 rare in British localities other than those now recorded, namely, 

 Bhabdogonimn tricarinatum, Sphecoidina huUoides, FuUenia sphce- 

 roides, and Pulvitiulina Menardii. 



The glacial sands and gravels of the east side of the Vale of 

 Clwyd are also described, and especial attention is called to an 

 esker-like mound of sand (gravel), occurring south-east of Diserth 

 Castle, formed of bedded deposits, the bedding of which generally 

 follows the outer form of the ridge. The ridge has Boulder-clay 

 upon the flanks, and is described as rising through the Boulder- 

 clay. 



III.— April 28, 1897.— Dr. Henry Hicks, F.R.S., President, in 

 the Chair. The following communications were read : — 



1. " On the Origin of some of the Gneisses of Anglese}'." By 

 Charles Callaway, M.A., D.Sc, F.G.S. 



The author still maintains the occurrence of two Pre-Cambrian 

 groups in Anglesey, the latter of Pebidian age. In the present 

 paper a description is given of the pi'oduction of gneissic structure 

 in the rocks of the earlier group occurring in the south of the 

 island. The products of metamorphism are similar to those described 

 by the author in the Malvern area, (i) Simple schists, granite is 

 converted into mica-gneiss, diorite into hornblendic or chloritic 

 gneiss, and felsite into mica-schist ; (ii) Injection-schists. In 

 Anglesey felsite plays the part which is taken by granite at Malvern, 

 and certain important diiferences arise. Gneiss of primary injection 

 is formed by the parallel veining of felsite and diorite, and the 

 author describes cases ; he also notices the occurrence of meta- 

 morphosed diorite-blocks in grey gneiss, which afford evidence of 

 its eruptive origin. Gneiss of secondary injection is well seen in 

 the Llangaifo cutting, and is explained in a manner similar to that 

 given for an infiltration-gneiss at Malvern, felsite being substituted 

 for granite. The infiltration-products are mainly chlorite, iron- 

 oxide, and epidote, and out of the chlorite, with the addition of 

 materials from the felsite, black mica has sometimes been con- 

 structed. The changes have occurred along planes of discontinuity 

 formed subsequently to the consolidation of the rocks. 



2. " Note on a Portion of the Nubian Desert South-East of 

 Korosko." By Captain H. G. Lyons, K.E. F.G.S, With notes 

 on the Petrology by Miss C. A. Eaisin, B.Sc. (Communicated by 

 Professor Bonney, D.Sc, F.R.S., V.P.G.S.) And Water-Analyses 

 by Miss E. Aston, B.Sc. (Idem.) 



A general description of the physical structure of the area, which 

 consists mainly of Nubian Sandstone and crystalline rocks, is given. 

 Coming from Korosko to the Murrat Wells, the crystalline rocks are 

 first met with on the east side of Jebel Eaft. The strike of these 



