fe) THE DESEADO FORMATION OF PATAGONIA 
AMEGHINO, 1906* WILCKENS, 1906{|/ORTMANN, 19orf 
vo . * 
& terrestrial marine 
8 
_ 
a 
b Patagonian Patagonian 
3 (transgression) 
4 
o 
5 
Q Deseado 
ep (regression) 
e) 
Santa Cruz 
a Notohippus 
g Astrapotheri- | Patagonian Casamayor 
oa culus (regression) 
Colpodon 
2 Deseado Sehuen 
3 Astraponotus St. George 
wes Casamayor Salamanca (transgression) 
oO 
a 5 Roca 
a) Luisa 
*Formations Sedementaires, p. 498, Anal. Mus. Nac. Buenos Aires, ser. 
he by cer 
+t 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 
