BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 

 Vol. 33, pp. 703-764 November 2, 1922 



FRONT RANGES OF THE ANDES BETWEEN SANTA CRUZ, 

 BOLIVIA, AND EMBARCACION, ARGENTINA 1 



BY KIRTLEY F. MATHER 



{Presented before the Society December 28, 1921) 



CONTENTS 



Page 



Introduction 704 



Bibliography 706 



Physical geography 707 



General 707 



Mountain ranges 707 



Sierra de Santa Cruz 707 



Sierra de Florida 707 



Sierra de Limon 709 



Sierra de Charagua 711 



Sierra de Mandiyuti 715 



Sierra de Guarui 717 



Sierra de Aguarague 717 



Sierra de Vitiacua 719 



The Chaco 721 



Intermontane lowlands 723 



Drainage system 725 



Physiographic history 726 



Stratigraphy 729 



General statement 729 



Espejos formation 730 



Los Monos shale 731 



Bermejo series 733 



Origin of the name and limit of the series 733 



Oquita formation ; 734 



Mandiyuti conglomerate 736 



Machareti formation 739 



-Vitiacua limestone and chert 739 



Tacuru formation 744 



Tatarenda formation 746 



Quaternary deposits 750 



Geologic structure 750 



General statement , 750 



Florida fault 753 



1 Manuscript received by the Secretary of the Society May 26, 1922. 



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