LATE TERTIARY PLANTS FROM JANCOCATA, 

 BOLIVIA * 



By EDWARD W. BERRY 

 DESCRIPTION OF THE LOCALITY 



The fossil plants that form the basis of the present contri- 

 bution were collected by M. Roman Kozlowski, formerly 

 director of the Escuela de Ingenieros at Oruro, Bolivia. They 

 were obtained at an altitude of about 12,675 f eet on tne 

 Cerro Jancocata which is approximately 12 km. southeast of 

 the town of Santiago in the province of Pacajes, the most 

 westerly province of the Department of La Paz, Bolivia. 

 This locality is 135 km. southwest of La Paz, 75 km. almost 

 due west of Corocoro, and 445 km. northwest of Potosi. 



The plant horizon is at (a) in the accompanying view of 

 the locality and the section may be described as follows : The 

 total thickness exposed is about 100 meters. The lower part 

 consists of reddish clays with gypsum concretions, alternat- 

 ing with gray clays and some calcareous layers, the whole 

 entirely unfossiliferous. The upper part of the series is pre- 

 dominately a kaolinized andesitic tuff, with some beds of 

 sand and conglomerate. About midway in the upper part 

 of the section is the white plant bearing tuff. The beds are 

 all gently folded and were evidently deposited subsequent 

 to the main folding of the Andes, although probably before 

 the major elevation of the ranges. They are widely distri- 

 buted in the provinces of Pacajes and Carangas and are con- 

 sidered to be fluvio-lacustrine by Kozlowski, although prob- 

 ably the more general term continental would be more ap- 

 propriate. 



The Jancocata beds are in part the equivalent of the so- 

 called Mauri volcanic series of Douglas x and they may repre- 

 sent the uppermost of the three series at Corocoro named by 



* George Hnntington Williams Memorial Publication No. 19. 

 Douglas, J. A., Quart. Jour. Geol. Soc., Lond., vol. 70, p. 23, 1914. 



