32 



Windhausen — The Cretaceous- Tertiary 



above the strata with Lahillia luisa in the region of the 

 Cerro Cazador near the Lago Argebtino must be taken 

 as deposits of the San Jorge. Unfortunately the data 

 published by Hauthal and Wilckens 78 are insufficient, and 

 Hauthal's attention was mainly absorbed by the discovery 

 of the marine Senonian strata at the bottom of these 

 sediments. However, from these reports springs the 

 important fact that the strata in question are in obvious 

 contrast to its base. According to Wilckens, the ammo- 

 nite- and baculite-bearing deposits of the Upper Seno- 

 nian pass over little by little into the strata with Lahillia 

 luisa, and there the cephalopoda-fauna experiences a 

 gradual impoverishment. Above that follow sediments 

 of quite a different character in a lithological as well as 

 faunistic sense: a complex of soft brownish sandstones 

 with Ostrea ultimce spei, Ostrea Ameghinoi and other 

 shells, but without ammonites and baculites. Wilckens 

 points out the fact that this fauna is not identical either 

 with the Upper Senonian mollusca or with the fauna of 

 the Patagonian Formation. This faunistic and strati- 

 graphic break at the bottom as well as at the top indi- 

 cates important events of earth history. As the other 

 molluscan genera referred to by Wilckens agree with 

 forms represented in the San Jorge, there are well 

 founded reasons for supposing a direct connection of 

 these deposits with the San Jorge. It is desirable that 

 future investigators dedicate special attention to the 

 study of these fossil-bearing horizons above the Upper 

 Senonian. 



78 Hauthal, Wilckens uud Paulcke, Die obere Kreide Siidpatagoniens, etc. 



Fig. 3 (p. 33). 



Explanation of Symbols: 



Area of the epicontinental sea. 

 Known shore-lines. 



"# 





Constructed shore -lines. 



Shore line coinciding with the great 



1 fault at the northern border of the 



ancient Patagonien continental 

 platform 



<0 

 .— --^p, Outcrops of the ancient Pata - 



(Sj^-^ gonian continental platform. 



* 



s= 



Ancient structural elements of 

 different age (Pampine Sierras, 

 Sierras of Buenos Aires , Sierra 

 Pmtada , Praecordi II era etc.). 

 (At present partly in -Hie underground , or 

 affected by subsequent movements]. 



A n d in e reg i on ( After th e fi rst 

 phase of folding). 



Variegated Sandstones of +he 

 Upper Cretaceous , 



/mostly continental deposits]. 



Upper Cretaceous, marine facies. 

 (Upper Senonian). 



