8 Rev. W.D. Conybeareon a Geological Map of [Jan., 



Angers, and Fontenay, to Sables d'Olonne, will indicate the 

 eastern boundary of those chains which extend westward to the 

 Atlantic. The Loire, however, breaks through their line in its 

 course to the sea, and where they open to give it passage, a small 

 coal basin reposes against them. 



(D.) Central Group of France. 



The primitive rocks, after plunging for a short interval beneath 

 the secondary calcareous beds, reappear in great force in the 

 central regions of France, constituting an extensive body of 

 mountains, sending out various ramifications between the 

 sources of the Loire, the Garonne, and their tributary streams, 

 being bounded on the east by the Rhone ; and occupying the 

 greater portion of the departments, Haute Vienne, Creuse, Cor- 

 reze, Puy de Dome, Cantal, Loire, Haute Loire, Rhone, Lozerre. 

 Viewed generally, this group presents a vast inclined plain rising 

 gradually from NE to SW, in which last direction is its 

 principal and highest chain, that of the Cevennes. Granite 

 is the predominant rock in this vast mountain plain, slates 

 appearing to be of rare occurrence. In the departments Puy de 

 Dome, Cantal, Haute Loire, and Ardeche (including the ancient 

 districts of Auvergne Forez Velay, and Vivarais), ridges and 

 conical peaks of basalt, of Trachyte, and of volcanic scoriae, are 

 superimposed on the elevated granitic plain, and constitute the 

 loftiest summits of this group. Similar peaks are also scattered 

 over the more recent deposits contiguous to the primitive chains. 

 Many of these peaks contain regular craters, and streams of 

 undoubted lava may be traced from them. Many of the valleys 

 descending from this mountain group contain deposits belonging 

 to the coal formation reposing against the primitive chain, 

 sometimes also the tertiary deposits from upfillings in the valley. 

 The north-eastern branch of these ridges (called the Beaujolais 

 mountains) extends between the Loire and the Rhone as far as 

 the district of Morvan on the north of Autun, where the oolitic 

 chains of the Cote d'Or overlie and abut against the granite. 

 The chains above described approach on the SE towards the 

 Pyrenees, leaving but a narrow interval along which the great 

 Canal de Languedoc is conducted ; but on the SW, the broad 

 basin of the Garonne is interposed between them, exhibiting the 

 regular series of secondary formations, from the new red sand- 

 tone to the tertiary beds. 



(E.) Pyrennees. 



The Pyrennees consist, according to Raymond, of five parallel 

 zones ; namely, a central zone of granite bounded by two schis- 

 tose zones, which are in turn succeeded by the exterior calcare- 

 ous chains ; the granitic axis, however, does not, as is usual in 

 mountain chains, form the loftiest crest ; but, though towering 

 above the collateral chains on the side of France, is itself over- 



