4 Windhausen — The Cretaceous-Tertiary 



pointed out the fact that an obvious hiatus separates the 

 folded, bended and metamorphosed sediments (the 

 so-called "clayslate-formation" of Darwin 8 ) in the inte- 

 rior of the Patagonian Cordillera from the Tertiary 

 Formations in the zone of the mesetas (tableland). 

 Having found fossils at various localities, Steinmann 

 assumed that the folded and metamorphosed sediments 

 are partly of Early and Middle Cretaceous and partly of 

 Upper Cretaceous age. By the term "Patagonian Ter- 

 tiary" was meant chiefly the marine deposits of the 

 so-called "Patagonian Formation" or "Patagonian 

 Beds" (later called by Wilckens also "Patagonian 

 Molasse") which are an equivalent of the Navidad Beds 

 in Chile and have been correlated by Ortmann with the 

 Lower Miocene on the basis of collections made by the 

 Princeton University Expedition to Patagonia. 9 



In contrast to Steinmann, Hauthal 10 and Ameghino 11 

 emphatically defended the idea of a gradual transition 

 from Cretaceous to Tertiary in Patagonia, Hauthal from 

 a stratigraphic and Ameghino from a paleontological 

 point of view. Going back to the observations of Stein- 

 mann, Wilckens proved the improbability of these opin- 

 ions and made a summary of Patagonian stratigraphy, 

 which will always remain a standard work. 12 Starting 

 from the same point of view as Hauthal and Ameghino, 

 H. v. Ihering 13 assigned an Eocene age to the Patagonian 

 Formation and opposed the determination of age given 

 by Ortmann. 



This position of H. v. Ihering was maintainable as long 

 as no other invertebrate fauna of Early Tertiary age 

 was known from the Patagonian mesetas. The marine 

 molluscan fauna of Roca in the Rio Negro, discovered by 



8 Geological Observations on Coral Eeefs, Volcanic Islands and on South 

 America, being the Geology of the Voyage of the Beagle, etc., pp. 140, 

 etc., London, 1851. 



Keports of the Princeton University Expeditions to Patagonia, 1896- 

 1899. Volume 4, 1902. 



10 uber patagonisches Tertiar, etc., Zeitschr. deutsch. Geol. Geselisch., 50, 

 pp. 436-440, Berlin, 1898. 



11 L 'age des formations sedimentaires de Patagonie, Anales Sociedad 

 Cientifica Argentina, vols. 50-54, Buenos Aires, 1903. — Les formations 

 sedimentaires du Cretace Superieure et du Tertiaire de Patagonie, Anales 

 Museo Nacional de Buenos Aires, (3), vol. 8, 1906. 



12 Die Meeresablagerungen der Kreide- und Tertiaf ormation in Pata- 

 gonien, N. Jahrb. Min., Beil.-Bd., 21, 1905. 



13 Les mollusques f ossiles du Terciaire et du Cretace Superieur de 

 1 'Argentine, Anales Museo Nacional de Buenos Aires, 7, 1907. 



