Vol. LVII of Whole Series. 



Price 2s. 6d. 



The 



Geological Magazine 



riDontblP 3ounial of (Beolotjvn 



WITH WHICH IS INCOKPORATED 



THE GEOLOGIS" 



EDITED BY 



APR 2 S 1920' ) 



HENRY WOODWARD, LL.D., BVR^,S. ^ 



AND 



R. H. RASTALL; M.A. 



ASSISTED BV 



Pkof. J. W. GREGORY, D.Sc, P.R.S. Sir JETHRO J. H. TEALL, Sc.D., F.R.S. 



F. H. HATCH, Ph.D., M.Inst. M.M. Prop. W. W. WATTS, Sc.D., F.R.S. 



Pkof. J. E. MARR, Sc.D., F.R.S. HENRY WOODS, M.A., P.R.S. 



Dr. a. SMITH WOODWARD, P.R.S. 



APRIL, 1920. 



CONTENTS :— 



Page 

 Editorial Notes 145 



Original Articles. 



The Pre-Glacial Valleys of Arran 

 and Snowdon. By J. W. 

 Gregory, F.R.S. (With 8 

 Text-figures.) 148 



The Limit between the Silurian 

 and Devonian Systems. By L. 

 Dudley Stamp 164 



Carboniferous Fossils from Siam. 

 By F. R. CowPER Reed. (With 

 Plate II.) [Concluded.) 172 



Reviews. 



Block Mountains in New Zealand. 178 



Tin Ores, 1919 179 



Marine Boring Animals 180 



Handbook of Mineralogy 181 



Reviews [continued). Page 



Phosphates of South Australia ... 181 



Geology of Sinoia, Rhodesia.. 18.3 



Ores of Tonopah, Nevada 183 



Suess as Palaeontologist 184 



Mines of South Australia 184 



Classification of Nepheline Rocks. . . 185 



Reports and Proceedings. 



Edinburgh Geological Society 186 



Mineraiogical Society 188 



Geologists' Association 189 



Liverpool Geological Society 189 



Correspondence. 



E. H. Cunningham-Craig 190 



Dr. A. Barker 191 



Dr. F. A. Bather 191 



C. Carus-Wilson 192 



Dr. J. W. Evans 192 



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