Structure of the Eastern Alps . 305 



towards the eastern termination of the chain ;" but being unable to define 

 their lower limits, we did not think it necessary, in our mere outline sketch, 

 to attempt their separation from the younger Alpine limestone. 



1. Primary Rocks of the Central Axis. 



We stated that the rocks of the central axis have their culminating- peaks 



on the eastern borders of the Tyrol, where the Grosse Glockner and the 



Venediger Alp rise to the respective elevations of 12,281 and 12,201 English 



feet above the level of the sea* ; that in their range to the east, the central 



ridges, dividing Carinthia from the Salzburg country, diminish gradually in 



elevation ; and tliat after following the direction of the Mur for a considerable 



distance, they finally separate into two irregular branches, one of which is 



prolonged into the Bacher Gebirge, and forms the south-western boundary of ' 



the Gratz basin ; while the other is continued in the direction of the principal 



axis of the Alps, and forms the boundary between the basins of Vienna and 



Styria. Such a general description was sufficient for our purpose, and we 



added, chiefly on the authority of V^on Buch's map, that the main branch, in 



the direction of the central axis, after disappearing under the recent deposits 



connected with the basin of Vienna, emerges in the neigiibourhood of Pres- 



burg, and is prolonged into the mountains which range in a north-easterly 



direction towards the Carpathian chain. 



In 1829 we had no means of ascertaining whether the old rocks of the 

 principal axis of the Alps rose from beneath the newer deposits in any part 

 of the basin of Viennaf ; but during last summer Professor Partsch and one 

 of the authors ascertained the existence of a nucleus of primary or transition 

 rocks in the low ridge of Leitha Gebirge, which separates Austria from Hun- 

 gary. The old rocks of this ridge form a true anticlinal axis, from which the 

 tertiary deposits dip in opposite directions ; and there can no longer be any 

 doubt of the prolongation of the Alpine chain in the direction above indicated. 

 Any mineralogical details connected with the structure of the primary axis 

 would be out of place in this introductory sketch. We may however observe, 

 generally, that in its range towards the east, the granite or granitoid gneiss, 

 which forms some of its higher western elevations, seems gradually to give 

 way to mica schist and other primary slaty rocks ; and that in some places on 



* The published heights which we have copied and reduced are 11,775 and 11,698 Vienna 

 feet above the level of the sea. 



t We were however aware, on the authority of Von Buch's map, that the primary system 

 did emerge near the south end of the Neusiedler See. 



VOL. III. SECOND SERIES. 2 R 



