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. [h. 
Ostrea riongrensis v. Th. 
Ostrea ameghinoi v. Th. 
Chlamys salamanca v. lh. 
Rostellaria striatissima v. Th. 
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 ocean. 
In section B we found the above fauna in layer 1 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 I 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 
