J. B. Hatcher — Geology of Southern Patagonia. 341 



where they are characterized by the scarcity of herbivorous 

 marsupials and bird remains and the abundance of the remains 

 of carnivorous marsupials, edentates, ungulates, rodents, etc. 



There has been much doubt in regard to the age of the 

 Santa Cruz beds. Darwin* was the first to determine that 

 they were distinct from the Patagonian beds and to suggest 

 their true stratigraphic position in regard to the latter. Dr. 

 Florentino Ameghinof and his brother Carlos Ameghino, dur- 

 ing the first five years of their labors on the mammalian fauna 

 of the Santa Cruz beds, supposed them to underlie the Pata- 

 gonian beds which most conchologists agree in referring to the 

 Eocene. They therefore considered the Santa Cruz beds as 

 Lower Eocene and the Patagonian beds Upper Eocene. Finally 

 on his sixth journey into this region Carlos Ameghino was 

 able to determine the exact stratigraphic relations of these 

 deposits, and their relative position in the Tertiary scale was 

 exactly reversed. 



So far as any observations bearing upon the stratigraphic 

 relations of the Santa Cruz beds are concerned, there is abso- 

 lutely nothing against referring to them any age from Lower 

 Miocene to Lower Pliocene. That they are not older than 

 Middle Miocene is pretty clearly shown, since they have been 

 seen to rest unconformably upon the Supra-Patagonian beds, 

 in regard to the invertebrate fauna of which Dr. Ortmann 

 writes as follows : " The most interesting form of the Supra- 

 Patagonian beds is the Scutella. According to Zittel {Hand- 

 ouch der Palaeontologie, vol. i, p. 522), all the species of 

 Scutella are found in the Oligocene and Miocene ; so that this 

 fact tends to confirm Moericke's opinion (N. Jahrb. Min., etc., 

 Beil. Bd. x, pp. 593 and 596) of the Miocene age of the Pata- 

 gonian beds, at least of a part of the so-called Patagonian beds. 

 If this is true, the Santa Cruz beds overlying the Scutella 

 beds cannot be Eocene." 



In any attempt to correlate the Santa Cruz beds with other 

 Tertiary strata of either Europe or North America, nothing 

 will be found of more value than the remarkable vertebrate 

 fauna which they contain. There is absolutely no ground, 

 from a stratigraphical standpoint, for presuming that the mam- 

 malia of this region were any more advanced in early Tertiary 

 times than were the mammalia of the northern hemisphere; 

 hence, notwithstanding the fact, that the Santa Cruz fauna is 

 so dissimilar to any known in either Europe or North America, 

 if among the ungulates, rodents and other orders common to 



* See Geol. Obs. on S. A., Darwin, p. 117. 



f See Enumeration Synoptique des Especes de Mamiferes Fossiles des Forma- 

 tions Eocenes de Patagonie, par Florentino Ameghino, pp. 4-5 (Buenos Aires), 

 1894. 



