Geology and Mineralogy. 461 



Unders., No. 229, pages 210 and 1 map, 1910. Here is presented 

 first a general and second a somewhat detailed statement of the 

 Cambrian, Ordovician and Silurian or Gotlandian deposits of all 

 Sweden. There is also a very extensive bibliography. It is one 

 of the guides to the excursions given after the meetings of the 

 Geological Congress at Stockholm last summer. The book is of 

 great value to all students of early Paleozoic stratigraphy. 



c. s. 



6. Geologisch-petrographisehe Studien in der Patagonischen 

 Cordillera ; von P. I). Quensel. Bull. Geol. Inst. Upsala, vol. 

 xi, 1-113, 1910, figs, and geol. map. — The writer during a period 

 of two years, partly by land travel and partly by boat in the 

 fiords, has made a fairly general geological reconnaissance in the 

 chains of the southern Andes, from Cape Horn northward to 41° S., 

 a distance covering 15° of latitude. Availing himself of hitherto 

 published material, which was rather scant, and his own obser- 

 vations, he presents a geological map covering this stretch, and 

 extending from the Pacific on the west to the pampas on the east. 

 Although the work is chiefly devoted to presenting the results of the 

 petrographical investigation of the material collected, these are 

 accompanied by geological observations, which, taken together 

 with a brief resume of the geology of the area published by him in 

 " Geologische Rundschau" (Band 1, p. 21, 1910), are sufficient to 

 throw much light on the geology of this little known region. 



The western, or coast, Cordillera, fronting on the Pacific, is 

 composed of an enormous stretch of granular igneous rock, the 

 andendiorite of Stelzner. This immense mass reaches from Cape 

 Horn in nearly 56° S. to 47° S., and is deeply dissected by a 

 remarkable system of fiords, comparable to those of Norway and 

 Alaska. From 47° northward it swings more inland, and is 

 replaced on the coast by islands of metamorphosed older sedi- 

 ments. The author states that it has not the monotonous petro- 

 graphic character formerly attributed to it, but shows much differ- 

 entiation into types varying from acid potash granites, and quartz 

 diorites, through syenites and augite-diorites, into gabbros, and is 

 accompanied by systems of aplitic and lamprophyric dikes. Inland 

 it is much covered by glaciers and seas of ice. The author is 

 inclined to place the intrusion at the end of the Mesozoic; unfor- 

 tunately no direct contacts with fossiliferous strata have been 

 found, and this age is inferred from general considerations. In 

 several places effusive masses of andesite and basalt were found. 



In regard to the central and east Cordillera the geological for- 

 mations and structure are very different from the foregoing, and 

 also vary in the long stretch over which reconnaissance was made. 

 Near the strait of Magellan the central chain is a folded range, 

 consisting of sedimentary beds belonging to the Cretaceous, and 

 against which the Tertiary of the pampas is gently inclined ; 

 there is probably an unconformity between them. In the north- 

 ern part of this stretch great masses of quartz-ijorphyry occur 

 with tuffs and breccias. 



