'1 \ 



THE 



GEOLOGICAL MAGAZINE 



ffDontbl^ 3ournal ot 6colot3\>. 



WITH WHICH IS INCORPORATED 



THE GEOLOGIST. 



EDITED BY 



HENRY WOODWARD, LL.D., F.R.S., F.G.S., F.R.M.S. 



I.ATE OP THE BRITISH MUSEUM OP NATURAL HISTORY ; PKESIDKNT OF THE 

 PAI.aiONTOGRAPHICAL SOCIETY ; ETC. 



AND 



R. H. RASTALL, M.A., M.Inst.M.M, F.G.S., 



UNIVERSITY LECTURER IN ECONOMIC GEOLOGY, CAMBRIDGE. 



ASSISTED BY 



Professor J. W. GREGORY, D.Sc, F.R.S.. F.G.S. 



F. H. HATCH, Ph.D., M.Inst.M.M. 



Professor J. E. MARR, Sc.D., F.R.S., F.G.S. 



Sir JETHRO J. H. TEALL, Sc.D., LL.D., F.R.S., V.P.G.S. 



Professor W. W. WATTS, Sc.D., LL.D.. M.Sc, F.R.S., F.G.S. 



HENRY WOODS, M.A., F.R.S. 

 ARTHUR SMITH WOODWARD. LL.D., F.R.S., F.L.S., F.G.S. 



VOL. LVII OF WHOLE SERI^^^-^' 



JANUARY— DECEMBER, 1920- 



LONDON : 





DULAU ct CO., LTD., 34-36 MARGARET STREET, 



CAVENDISH SQUARE, W. 1. 



1920. 



