112 M. Fournet's Opinions regarding the 



those which may be regarded as the ramifications of the prin- 

 cipal trunk ; likewise on the course and declivity of those which 

 are in an opposite direction to this principal valley ; and of the 

 main course of the water, both on the side towards the Loire, 

 and on that towards the Saone. Concerning this latter river, 

 ■whose course is from north to south, it is to be remarked, that 

 its tributaries, the Jardine, and especially the Brevanne, enter 

 it, flowing from the south-west to the north-east ; and even 

 from south to north. It is the same with the Gier in relation 

 to the Rhone. Another remarkable distribution, and nearly 

 of the same kind, is the convergence of all the valleys towards 

 Arbresle as towards a great basin. 



2d, When the structure and the inclination of the mineral 

 strata, as well as the nature of the hills which confine and form 

 these valleys, have been studied, we may then pursue these re- 

 lations further by recognising that this main point, this kind 

 of hollow where the town of Arbresle is situated, may be con- 

 sidered as a uniting point of three different systems, or of three 

 distinct axes in the relief or conformation of the country ; axes 

 ■which M. Fournet has very clearly determined by the mam- 

 millary tops and the summits which characterize them, by the 

 directions which they follow, and the localities which they tra- 

 verse, — characters which are very distinct upon a map, but of 

 which no description can convey a clear idea. 



Since the time when M. Fournet gave in his work to the 

 Academy, having assiduously prosecuted his observations on 

 the relief of the soil, he has discovered a fourth axis of eleva- 

 tion, that, namely, which has uplifted the Lyonese Mont d'Or. 

 This axis is not very apparent in the Lyonois portion, but when 

 studied with all those helps which the theory of geological ele- 

 vations supply, M. Fournet very clearly demonstrates that the 

 Lyonois Mont d'Or ought to be referred to the elevation of the 

 Mountains of Pilate, the first of the Jura elevations, and dif- 

 fering from it only in degree. 



It is upon the three first axes, indicating three systems or 

 epochs of distinct elevation, that M. Fournet most insists, by 

 collecting all the facts which agree in establishing the reality of 

 this succession of geological phenomena. These proofs are 

 drawn from the nature of the rocks, from their inchnation or 



