1823.] the principal Mountain Chains of Europe. 215 



the Ebro from below Saraeossa to above Tudela. It is difficult 

 to speak of a country whose geology has yet never received a 

 strictly scientific examination ; but enough is known to teach us 

 that the central and western districts are principally occupied 

 by primitive chains, while the east and south-east (with the 

 exception of the transition chain of the Sierra Nevada) exhibit 

 little but calcareous mountains, among which gypsum is plentifully 

 interspersed. As we shall hereafter see that the limestone form- 

 ation, answering in age to our magnesian limestone, swells into 

 great importance on the Continent, and constitutes large moun- 

 tain zones encircling the Alps, &c. which are in like manner 

 characterised by the intermixture of gypsum, it is no improbable 

 conjecture that these deposits belong to the same period. 



(E.) The Alps. 



We find these formations forming a zone on either side of the 

 Alps ; on the north, interposed between the older rocks and 

 great Nagelflue of Switzerland, which was once itself considered 

 as belonging to them, but has been proved by subsequent 

 researches to be of much more recent date, and contemporaneous 

 with the sandstones of the basin of Paris. The red sand- 

 stone is here intimately associated with alpine limestone, which 

 corresponds with the calcareous formations already described as 

 coeval with our magnesian limestone ; and gypsum and salt may 

 be found interspersed through the whole series. A similar cha- 

 racter applies to the zone on the south side of the Alps ; here 

 the red sandstone may be seen to the greatest advantage in 

 the valley of the Adige, ten miles north of Trent, and in the valley 

 of Avisio, which descends from the Val di Tassa into that of the 

 Adige. In the same neighbourhood a porphyry occurs asso- 

 ciated with these formations on the south of the Alps only. 



The reader is referred for further particulars lo the excellent 

 memoir of Prof. Buckland, Annals of Philosophy, June, 1821. 



It is probably the limestone of this formation belonging to the 

 southern alpine zone, which extends into Carinthia, Istna, Dal- 

 matia, &c. ; the limestone of the Apennines, and much of that 

 in Greece, may also, perhaps, be referred to the same era. 



It is not to be understood that all the limestone chains border- 

 ing the Alps belong to the present series. Parts on the exterior 

 are undoubtedly referable to the oolitic series ; and others, as it 

 should appear, parallel to the limestones associated with our 

 green sand. The great disturbances which have affected these 

 colossal chains, and the almost inaccessible nature of much of 

 the ground, must long leave considerable obscurity on the exact 

 demarcation of their constituent formations. 



(F.) Districts North of the Jura and on the Banks of the Rhine. 

 The strata of the Jura chain cropping out to the north exhibit 



