754 



K. F. MATHER FRONT RANGES OF THE ANDES 



Abapo to Limon, the upper Tacuru and lower Tatarenda beds dip east- 

 ward at angles between 12 degrees and 42 degrees, with strike varying 

 from north 10 degrees east to north 50 degrees west. The flexures at 

 that locality seem to represent the northwest extension of the Charagua 

 anticline or the dying out of the Oquita-Taimbermi fault. 



Near Eincon the strata also dip toward the east ; the Tatarenda forma- 

 tion, in the low hills near that hamlet, displays dips of 10 degrees to 12 

 degrees, while the Bermejo-Tacuru series, a half mile to the west, dips 

 eastward at angles of 20 degrees to 30 degrees and forms hogbacks along 



SKETCH 



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 STRUCTURE 



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 SIERRA DE CHARAGUA 

 BOLIVIA 





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FlGUSE 20. — Sketch Mai> and Structure Section of a Portion of the Sierra rfe Vitarayua, 



Bolivia 



the eastern front of the sierra. Evidently the Limon fault decreases in 

 magnitude toward the south and gives place at Rincon to an anticlinal 

 fold with little breaking along its axial plane. At Tatarenda the sands 

 and shales of the Tatarenda formation strike north 8 degrees east and 

 dip eastward at an angle of 58 degrees. 



CHARAGUA AXTICLIXE 



The Sierra de Charagua is structurally a long, narrow, strongly com- 

 pressed, asymetrical anticline. As shown in cross-section in figures 18 



