No. 501. 



Decade V.— Vol. III.— No. III. 



Price Is. 6d. net. 



THE 



GEOLOGICAL MAGAZINE 



onthtj Jouiiiial of ^^alaflj. 



WITH WHICH IS INCORPORATED 



TtiE GhElOLOGHST." 



EDITED KY 



HENRY WOODWARD, LL.D., F.R.S., F.G.S., &c. 



ASSISTED BY 



WILFRID H. HUDLESTON, F.R.S., &c., Dr. GEORGE J. HINDE, F.R.S., &c., and 

 HORACE B. WOODWARD, F.R.S., &c. 



MARCH, 1906. 



OOnSTTEI^TS. 



I. 



104 



Okiginal AkticlEvS. Faffe 



The Geological History of South Africa. 

 By Dr. F. H. Hatch, F.G.S.,. 

 M.I.C.E., President of the Geo- 

 logical Society of South Africa 97 



The Physical History of the Great 

 Pleistocene Lake of Portugal. By 

 Professor Edward Hull, LL-D., 

 F.R.S., F.G.S 



Fossil Corals from Eastern Egypt, Abu 

 Roash, and Sinai. By Prof. J. W. 

 GiiEGORY, D.Sc, F.R.S., Glasgow 

 University. (Concluded.) 110 



Allotropic Forms of Silica as Con- 

 stituents of Igneous Rocks. By 

 Cosmo JoHNS,M. I. Mech.E., F.G.S. 118 



The Thickness of the Ice-Cap in 

 Glacial Periods. By EuxXst H. L. 

 ScHWAKz,A.R.C.S.',F.G.S., Rhodes 

 University College, Grahanistowu, 

 South Africa 120 



Further Notes on the Trimminghani 

 Chalk, Norfolk. (Concluded.) By 

 R. M. Bkydone, F.G.S. (Plates 

 YlllandlX.) 124 



Original Articles (continued). Paffe 

 A Method of Classifying Igneous Rocks 

 by their Chemical Composition. By 

 Dr.HuGHWARTH. (With a Table.) 131 



II. Reviews. 



Catalogue of the Fossil Plants of the 

 Glossopteris Flora. By E. A. 

 Newell Arber, M.A., F.L.S., 

 F.G.S 13.5 



Guide to the Fossil Reptiles, Am- 

 phibians, and Fishes in the British 

 Museum (Natural History). (Plate 

 XII.) 137 



III. Reports and Proceedings. 



Geological Society of London — 



January 24th, 1906 139 



February 7th 141 



Mineralogical Society of London 143 



IV. Correspondence. 



Machine-made Implements. By F. J. 

 Bennett, F.G.S 143 



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