■ 



THE 



QUARTERLY JOURNAL 



OF 



THE GEOLOGICAL SOCIETY OF LONDON. 

 Vol. LII. 



1. The ' SCHISTES LTTSTRES of MoNT JoVET (SAVOY). 



By J. W. Gregory, D.Sc, E.G.S. (Read November 6th, 1895.) 



The controversy as to the age and origin of the ' Schistes lustres ' 

 of the Western Alps has passed through three distinct stages. At 

 the beginning of the century these schists were included among the 

 primitive rocks. Even in the first decade, however, this idea was 

 refuted in a paper by Brochant, 1 which may still be read with 

 interest, owing to its excellent description of the physical features of 

 the Tarentaise. In this work, all the rocks of which Mont Jovet is 

 composed, with the exception only of the gypsum, were referred to 

 a series of * terrains de transition,' intermediate between the crys- 

 talline primitive rocks and the normal, secondary, stratified deposits. 

 Fifteen years later, a further advance was made, which restricted 

 the ' terrains primitifs ' within still narrower limits. Bakewell 2 

 then showed that the gypsums of Mont Jovet were regularly inter- 

 stratified with the limestones ; moreover, as he correlated the 

 anthracitic beds with the English Coal Measures, he included the 

 limestones in the ' upper secondary strata/ meaning thereby the 

 Permian and the Mesozoic. A second stage in the controversy was 

 entered upon with Elie de Beaumont's 3 epoch-making discovery of 

 belemnites in the limestones of Petit-Coeur, a hamlet 5 miles north- 



1 A. J. M. Brochant, ' Observations geologiques sur des terrains de transition 

 qui se rencontrent dans la Tarentaise et autres parties de la chaine des Alpes,' 

 Journ. des Mines, vol. xxiii. (1808) pp. 321-380. 



2 R. Bakewell, ' Travels ... in the Tarentaise and various parts of the 

 Grecian and Pennine Alps in the years 1820-1822,' London, 1823, vol. i. 

 pp. 295-300. 



3 Elie de Beaumont, ' Notice sur un Gisement de Yegetaux fossiles et de 

 Belemnites, situe a Petit-Coeur pres Moutiers, en Tarentaise,' Ann. Sci. Nat. 

 vol. xiv. (1828) pp. 113-127. 



Q.J.G.S. No. 205. b 



