FOLDS AND FAULTING. 475 



Cretaceo-jurassic limestones, the former being highly con- 

 torted and underthrust, while the Jurassic limestones overlap 

 them on both sides. 



The questions demanding solutions are therefore of the 

 most complex character ; and only careful research in each 

 mountain district, together with the widest application of 

 mapping and physical and microscopical investigation, 

 carried out by careful and indefatigable observers, can 

 reveal the true interpretation of the facts with which we 

 are now acquainted. It may be that as yet it is only 

 grasped in part, and that the key to the tectonic problems 

 has yet to be found ; but by the conscientious working out 

 of details a body of facts may be accumulated which will 

 enable geologists in the future to determine the full signifi- 

 cance of those phenomena whose effects are revealed to us 

 under such varied and impressive forms. 



BIBLIOGRAPHY. 



(10) SCHARDT, H. Bull. Soc. Vaud., ser. 2, vol. xx., p. 182, 1884-85. 



(11) Lory. De l'Orographie des Alpes de la Savoie et du 



Dauphine, p. 220, 1864. 



(12) Gilbert. Report on Geology of the Henry Mountains, 1877. 



(13) Bertrand. Bull. Soc. Geol., France, vol. xx., ser. 3, pp. 118- 



165, 1892. 



(14) BERTRAND. Soc. Beige. Geologic, tome vi., fasc. 1, pp. 13-28, 



1892. 



(15) Rothpletz. Geol. Querschitt. Ost. Alpen, 1894. 



(16) Rothpletz. Geo-Tecktonische Probleme, 1894. 



W. F. Hume. 



