Professor Favre on the Geology of the German Tyrol. 75 



granitic rocks are highly developed at the foot of theZillerthal, 

 between St Jacob and Pfunders. This granitic axis is inter- 

 sected at Mittelwald by the road from Sterzing to Brixen. 



The central chain likewise contains many other rocks, such 

 as true gneiss with white or black mica, as in the Zemm-Thal, 

 and in the bottom of the valley of Gastein, where they are 

 associated with hypersthenic syenite, at Isselberg, near Lienz, 

 and at Dollach, in Carinthia. 



It appears to me that true protogine is wanting in the Alps 

 of the Tyrol. 



The metamorphic rocks and stratified formations, not fos- 

 siliferous, constitute an ill-defined group, because, in the 

 lower part, they pass into crystalline rocks, and, in their upper 

 part, into' sedimentary fossiliferous rocks. They often them- 

 selves present characters of crystallisation. 



We have carefully studied these complicated i*ocks in the 

 long pass of Pfitsch-Joch. 



The most widely distributed, most common, and most im- 

 portant rock of this group, is an argillo-talcose slate, whose 

 characters are very variable. The Tyrolese geologists dis- 

 tinguished it by the name of argillaceous mica slate (Thon 

 glimmerschiefer). Near Zell, a mine of pyrites and auriferous 

 mispickel has been opened in this rock, which, according to 

 M. Burat, produces annually 35 marks of gold from 50,000 

 quintals of ore. Native gold is sometimes found likewise. 

 These ores have been probably formed at the same time with 

 the veins of quartz which traverse the rock. 



This argillo-talcose slate, enriched with an immense quan ■ 

 tity of garnets, occupies the summit of the pass of Pfitsch- 

 Joch (6741 feet), and is approached by varieties of gneiss, 

 slaty serpentine, and clay slate. 



It is well to observe the great analogy which exists be- 

 tween these rocks and those of the Canton of Valais. Their 

 resemblance is such that we ought not to despair of finding 

 fossils in them. In fact, we know that, in the latter country, 

 MM. de Charpentier and Lardy have found belemnites in 

 these rocks associated with the garnets.* 



* Ijaidy's I'ssay on tho ;;i"0},'nostic constitution of St Gotliard. (Memoires de 



