80 A CENTURY OF SCIENCE 



the United States, with Geological Remarks" (17, 274, et 

 seq.}. In these he describes the Cretaceous fossils and 

 demonstrates that the "Diluvial" and Tertiary strata of 

 the Atlantic border also have a long sequence of Creta- 

 ceous formations. In the opening paper he writes: "I 

 consider the marl of New Jersey as referable to the great 

 ferruginous sand series, which in Prof. Buckland's 

 arrangement is designated by the name of green sand, 

 . . . On the continent this series is called the ancient 

 chalk . . . lower chalk," etc. Again, the marls of New 

 Jersey are "geologically equivalent to those beds which 

 in Europe are interposed between the white chalk and 

 the Oolites." This correlation is with the European 

 Lower Cretaceous, but we now know the marls to be of 

 Upper Cretaceous age. Although Eaton objected stren- 

 uously to Morton's correlation, we find M. Dufresnoy of 

 France saying, "Your limestone above green sand 

 reminds me very much of the Maastricht beds," a correla- 

 tion which stands to this day (22, 94, 1832). In 1833 Mor- 

 ton announces that the Cretaceous is known all along the 

 Atlantic and Gulf border, and in the Mississippi valley. 

 "The same species of fossils are found throughout," and 

 none of them are known in the Tertiary. He now 

 arranges the strata of the former "Alluvial" as follows: 



Modern 



f Upper Tertiary (Upper Marine). 

 Tertiary J Middle Tertiary (London Clay). 



1^ Lower Tertiary (Plastic Clay). 

 Q ( Calcareous Strata / Cretaceous group, or Ferrugi- 



beCOndary < -Ci avTm ; C< QT1 ,q f nnnc SanH SPT-IP (9A 198^ 



Ferruginous Sand } nous Sand series (24,128). 



Western Cretaceous. In 1841 and 1843 J. N. Nicollet 

 announced the discovery of Cretaceous in the Rocky 

 Mountain area. Of 20 species of fossils collected by 

 him, 4 were said to occur on the Atlantic border, and of 

 the 200 forms of the Atlantic slope only 1 was found in 

 Europe. Here we see pointed out a specific dissimilarity 

 between the continents, and a similarity between the 

 American areas of Cretaceous deposits (41, 181; 45, 153). 



The Cretaceous of the Rocky Mountains was clearly 



