10 



THE DESEADO FORMATION OF PATAr.ONIA 



* Formations Sedementaires, p. 498, Anal. Mus. Nac. Buenos Aires, ser. 

 3, t. 8. 



f Neues Jarhbuch fur Mineralogie. bd. 21, p. 193. 

 | Princeton Expeditions Reports, vol. 4, p. 303. 



tylops) is contemporaneous with the Salamanca, the 

 Deseado with the Sehuen, and the Colpodon, the Noto- 

 hippus and Astrapothericulus with the Patagonian, thus 

 making the Deseado of Cretaceous age. After a very 

 detailed study of a large series of Patagonian fossils, Ort- 

 mann concludes that the Patagonian is of Lower Miocene 

 age. This is the most detailed study which has been made. 

 Wilckens coincides with this view, though feeling that the 

 Patagonian may have extended down a trifle into the last 

 of the Oligocene. This latter author finds a long gap be- 

 tween the Upper Cretaceous and the Patagonian, a period 

 when Patagonia was above water. It was during this 



