^ ' V N.H 



THE 



QUARTERLY JOURNAL 



GEOLOGICAL SOCIETY OF LONDON. 



EDITED BY 



THE PERMANENT SECRETARY OF THE GEOLOGICAL SOCIETY. 



Quod si cui mortalium cordi et curae sit non tantum inventis heerere, atque iis uti, sed ad ulteriora 

 penetrare ; atque non disputando adversarium, sed opere naturam vineere ; denique non belle et probabiliter 

 opinari, sed certo et ostensive scire ; tales, tanquam veri scientiarum fllii, nobis (si videbitur) se adjungant. 

 — Novum Organum, Prcefatio. 



VOLUME THE SEVENTY-SIXTH, 

 for 1920. 





LONDON: 

 LONGMANS, GREEN, AND CO. 



PARIS: CHARLES KLINCKSIECK, 11 RUE DE LILLE. 

 SOLD ALSO AT THE APAIiTMENTS OF THE SOCIETY. 

 1ICJIXXI. 



