14 THE DESEADO FORMATION OF PATAGONIA 



being typically developed opposite Pico Salamanca. 

 In this in the neighborhood of Pico Salamanca we found 

 the fauna typical of this horizon. 



Ostrea rostigera v. Ih. 

 Ostrea riongrensis v. Ih. 

 Ostrea ameghinoi v. Ih. 

 Chlamys salamanca v. Ih. 

 Rostellaria striatissima v. Ih. 

 Rostellaria sp. 

 Cytherea calcedonica H. 

 Discinia sp. 

 Diplodon sp. 



This Salamanca formation is considered by Wilckens as 

 the equivalent of the Roca as exposed on the Rio Negro, 

 and to the Luisa as exposed on the Rio Coyle. All agree 

 that the Salamanca is Upper Cretaceous and a period when 

 Patagonia was covered by the ocea'n. 



In section B we found the above fauna in layer I which 

 is just above sea level here. In layer 2 we found casts of 

 delicate marine shells (30 to 40 in number), representing 

 four or five species and as yet undescribed. They seem to 

 represent a deeper water facies of the Salamanca. In fact 

 all the shales represented by layers 1 to 5 evidently belong 

 to the Salamanca. Layer 5 was distinguished by having 

 in it .at a point some 200 yards north of the section line a 

 quantity of turtle shell fragments. 



Layer 7, consisting of coarser sandstones, was at the 

 point of the section, simply filled with a vast quantity of 

 fossil wood, most of it agatized, though some was carbon- 

 ized, and representing some eight species, mostly pines and 

 palms, the latter much scarcer. The tree trunks, hundreds 

 in number, lay scattered in all directions; but all were lying 

 horizontal, and there was no indication of stumps in place; 

 so I consider that the wood was driftwood. It is common 

 in the series of beds of this general horizon along the Gulf 

 of St. George. In the other layers up to the Patagonian 



