n6 STUDIES IN GEOLOGY, No. 4 



old as the Fagus flora of the Straits of Magellan and Tierra 

 del Fuego, which I have considered as Lower Oligocene in 

 age. 



Windhausen 24 has recently described the hitherto un- 

 known (wrongly correlated) transgression of what he calls 

 the San Jorge formation, which in the early Eocene flooded 

 the east coast of southern Argentina and penetrated north- 

 westerly up the Roca Valley. I mention this admirable con- 

 tribution in the present connection, since it has a bearing on 

 the age and antecedent history of the Magellanian beds. 



At Punta Arenas and elsewhere along the Straits of Ma- 

 gellan and at various localities in Tierra del Fuego a series of 

 sandy lignitic beds have been described by Ortmann, Hatcher, 

 Nordenskjold, and others, which are of the greatest interest 

 to paleobotanists because of the remarkable flora contained 

 near their base. The section somewhat abbreviated, is as 

 follows : 



1. Sands, lignitic sandstone, and conglomerate = horizon V of 



Hatcher = Patagonian formation of Ortmann Burdi- 

 galian . 



2. Sandstones with lignite beds and fossil plants = horizon IV 



of Hatcher = Upper lignites or Punta Arenas coal Mio- 

 cene Araucaria beds of Dusen = Aquitanian. 



3. Sandstone with oyster beds = horizon III of Hatcher = Oligo- 



cene. 



4. Sandstones with fossiliferous calcareous lenses = Oligocene. 



5. Fossiliferous beds = horizon II of Hatcher = Oligocene. 



6. Sand and sandstone with fossiliferous calcareous concretions 



and fossil plants = horizon I of Hatcher = Oligocene 

 Fagus zone of Dusen = Oligocene. 



7. Lignitic shales Lower lignites of Hatcher = Oligocene ( ?). 

 This section presents the record of a minor oscillation of 



the strandline with continental deposits passing into lagoonal, 

 and these into littoral and shallow-water marine, and then 



24 Windhausen, A., The problem of the Cretaceous-Tertiary boun- 

 dary in South America and the stratigraphic position of the San 

 Jorge formation in Patagonia. Am. Jour. Sci. (IV), vol. 45, 1918, 

 PP- 1-53- 



