MARINE UPPER CRETACEOUS AND A NEW ECHINO- 

 CORYS FROM THE ALTAPLANICIE OF BOLIVIA^ 



EDWARD W. BERRY 

 Johns Hopkins University, Baltimore 



It is not surprising that rocks of Upper Cretaceous age should 

 be present on the high plateau of Bolivia since the gypsiferous 

 shallow water phase of the Upper Cretaceous which represents the 

 several typically developed marine horizons that are so abundantly 

 represented in the more northern parts of the Andean geosyncline 

 (e.g., in central Peru), is conspicuous in the Eastern Andes of 

 Bohvia and furnished the writer with marine fossils at two localities 

 in the Department of Potosi. 



It may be true also that these marginal Upper Cretaceous 

 deposits of Bolivia, which are essentially reddish sandstones and 

 gypsiferous shales, with subordinate beds of limestone, are present 

 in considerable amount beneath the late Tertiary and more recent 

 deposits that make up most of the surface of the high plateau 

 except where older rocks are folded and project through these 

 thick, surficial deposits. 



No Cretaceous rocks have heretofore been known from the 

 Altaplanicie, however, although it is true that Steinmann called 

 the rocks at Corocoro Cretaceous. This was based solely on the 

 fact that the Corocoro rocks were red, and as the red rocks near 

 Potosi, 375 km. distant, were known to be Cretaceous, the unwar- 

 ranted assumption was made that the Corocoro rocks also were 

 Cretaceous. Many have followed Steinmann's opinion, as, for 

 example Douglas in his recent geological sections across the Andes,^ 

 although it would seem that if color is to be an age criterion, an 

 Englishman would consider red as indicative of Old Red or New 

 Red age, as did Forbes in his classic studies of Bolivian Geology. 



^ George Huntington Williams Memorial Pttblication No. g. 



^ J. A. Douglas, Quart. Jour. Geol. Soc. Lond., Vol. LXXVII (i9i4)> PP- 1-535 

 Vol. LXX (1920), pp. 1-61; Vol. LXXVII (1921), pp. 246-84. 



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