HASEMAN, GEOGRAPHICAL DISTRIBUTION IN SOUTH AMERICA IT 



The view held by Dr. Matthew and the writer (who have independently 

 and from different standpoints arrived at several identical and funda- 

 mental conclusions concerning the distribution of South American ani- 

 mals) in a general way was put forth in 1886 by Haacke as the North 

 Polar theory of the origin of land animals. 3 



Part I. Geology axd Topography of South America * 



DISTRIBUTION OF GEOLOGICAL HORIZONS 



It has been extremely difficult to map even the larger divisions of the 

 geological ages found in South America, since the exact age and extent of 

 many of the known formations have never been satisfactorily determined. 



Archean 



Archean rocks, as shown in a general way in Plate III, extend in a nar- 

 row belt, more or less broken, from Tierra del Fuego to the Isthmus of 

 Panama. A great depression east of the Bay of Arica lies between the 

 coastal Archean rocks of Chili and the inland Archean rocks of the north- 

 ern Andean region. Another great belt of Archean rocks extends from 

 Uruguay into the Serra do Mar and its various northern spurs of eastern 

 Brazil. Archean rocks have also been encountered in isolated places of 

 Patagonia, and a belt more or less broken extends from near Bahia Blanca 

 through the Cordova Mountains into southern Bolivia. Finally, rocks of 

 similar age have been encountered in northern Colombia, parts of Vene- 

 zuela and Guiana. 



The exact age of the crystalline schists, gneisses, granites, etc., which 

 underlie the Piano Alto has never been satisfactorily determined, but they 

 are usually considered pre-Cambrian or Archean on account of the entire 

 absence of fossils. The lined portion of Plate III indicates the extent of 

 these rocks. 



Lisboa, one of the most competent Brazilian geologists, has reported 

 crystalline rocks of pre-Cambrian ( ?) from near Miranda. Matto Grosso 

 and in the basins of Bio Apa and Eio Aquidauana. The writer observed 

 the basal highland rocks on the Bolivian side of Eio Guapore below the 

 mouth of Eio Verde and on the Brazilian side of the Guapore at the 



3 The bibliography gives a list of the publications which have been extremely useful to 

 me, and I take the opportunity here to acknowledge my indebtedness to the authors. Few 

 references have been given in the pages of this thesis, because it has been deemed ad- 

 visable to omit them for the sake of clearness and brevity. Therefore some common 

 information has been freely used. 



* In the preparation of this part of the thesis, the writings of Derby, Branner, Suess, 

 Eschwege, Ilartt, Hatcher. Steinmann. Phillipi, Stelzner. Hauthal. Katzer, Crandall and 

 numerous other authors given in the bibliography have been indispensable. 



