Reviews. 



Crystalline Rocks from the Andes. 



Untersuchungen an altkrystallinen Schiefergesteinen aus dem Gebiete der 

 argentinischen Republik von B. Kuhn. Neues Jahrbuch fur Min., 

 etc., Beit. Bd. VII., 1891, p. 295, 

 Untersuchung argentinischer Pegmatite, etc.,\oXi P. Sabersky, ib. p. 359. 

 Untersuchungen an argentinischen Graniten, etc., von J. Romberg, tb., 

 VIII., 1892, p. 275. 

 Travelers and foreign residents in South America are rapidly 

 furnishing information relative, not only to the volcanic, but also to the 

 older crystalline rocks composing the great Andes chain. Since the 

 early observations of Darwin, ' the petrographical collections made by 

 Stelzner during his three years' residence, as professor, at Cordova 

 (1873- 1876) have been described by himself^ and Franke, ^ while the 

 results of detailed studies of the more extensive collections gathered 

 by Stelzner's successor, Professor L. Brackebusch, are now beginning 

 to appear. Professor Brackebusch's residence in the Argentine Repub- 

 lic lasted from 1876 till 1883, and during this period he made numer- 

 ous scientific expeditions. ■♦ The petrographical material thus obtained 

 has been confided to specialists in Germany for study. Three papers 

 dealing with the crystalline schists (gneisses), ^ pegmatites, ^ and gran- 

 ites, ^ have recently appeared. The rocks of the granite contact -zones 



^Geological Observations in South America, 1846. 



= Beitrage zur Geologic und Paleontologie der argentinischen Republik ; I. Geo- 

 logischer Theil, 1885. 



3 Studien iiber Cordillerengesteine. Apolda, 1875. 



* Reisen in den Cordilleren der argentinischen Republik, Verh. der Gesellsch. fiir 

 Erdkunde. Berlin, 1891. 



s Untersuchungen an altkrystallinen Schiefergestenien aus dem Gebiete der argen- 

 tinischen Republik, von B. Kiihn. Neues Jahrbuch fiir Min., etc., Beit. Bd. VII., 1891, 



P- 295- 



^Untersuchung argentinischer Pegmatite, etc., von P. Sabersky, il>„ p- 359- 

 7 Untersuchungen an argentinischen Graniten, etc., von J. Romberg, ib., VIII., pp. 



411 



