Planktonic Foraminifera of Paleocene and Early Eocene Age from the 

 Gulf and Atlantic Coastal Plains 



By Alfred R. Loeblich, Jr., and Helen Tappan * 



Introduction 



nPHERE HAS LONG BEEN coiitroversv concerning the 

 -■■ geologic age of nearly eveiy formation throughout 

 the world referable to an age somewhere between the 

 Upper Cretaceous Maestrichtian and the Eocene Ypre- 

 sian. This is none the less true of the formations 

 here discussed which occur along the Gulf and Atlantic 

 Coastal Plains. The differing methods used in the 

 past to determine the age and correlation, range from 

 solely Uthologic and structural evidence to paleontologic 

 correlations variously based on brachiopods, mollusks, 

 bryozoa, ostracods, and Foraminifera. 



Because the planktonic Foraminifera have come to 

 be recognized in recent years as exceptionally valuable 

 tools for regional and world wide correlations, the 

 writers have made a study of these forms that occur 

 in certain Paleocene and lower Eocene strata. These 

 planktonic species are then made the basis for an inter- 

 regional correlation. The stratigraphic nomenclatiu-e 

 and age designations used in this report do not neces- 

 sarily foUow the usage of the U. S. Geological Survey. 



Strata from which planktonic species are here de- 

 scribed include the Velasco formation of Mexico, the 

 Kincaid and WiUs Point formations of the Midway 

 group of Texas ; the Pine Barren and McBryde members 

 of the ClaytoQ formation, the Matthews Landing marl 

 member of the Porters Creek clay, the Coal Bluff marl 

 member of the Naheola formation and the Salt Moun- 

 tain limestone, all of the Midway group of Alabama; 

 the Nanafalia formation of the Wilcox group of Ala- 

 bama; the Brightseat formation of Maryland, the Aquia 

 formation of Maryland and Virginia, and the Horners- 

 town and Vincentown formations of New Jersey. For 

 purposes of comparison, the planktonic species of the 

 type Danian of Denmark are also described and illus- 

 trated. The Wilcox group of Texas and the Porters 

 Creek clay and the Oak Hill member of the Naheola 

 formation of Alabama contained no planktonic Fo- 

 raminifera, in the samples studied, hence are not further 

 discussed in the present report. Samples of the imder- 

 lying Cretaceous horizons were also exaniined in each 

 area, but their quite different faunas are not here 

 described. 



• Helen Tappan Loeblich, U. 8. Geological Survey and Research Associate, Smith- 

 sonian Institution. 



Previous Correlations and Age Assignments 



Velasco Formation 



The Velasco formation of the Tampico embayment 

 of Mexico was first separated from the Upper Cre- 

 taceous Mendez formation by Cushman and Trager 

 (1924) and was then thought to be related to the Taylor 

 marl of Texas. Later (1926), Cushman stated that it 

 was equivalent to the Navarro of Texas. Dumble and 

 Applin (1924) described the same sequence of beds as 

 Tamesf and considered them as lower Eocene. 



Midway Group 



The Midway group was originally described from 

 Alabama, and since 1894 has been generally recognized 

 as including the oldest Tertiary beds of the Gulf 

 Coastal Plain. It was long considered by the U. S. 

 Geological Survey to be lower Eocene in age (Wil- 

 marth, 1938, p. 1366). However, about 30 years ago, 

 Gayle Scott (1926, p. 161) had con-elated the Midway 

 group of the Gulf Coast with the Danian, placing the 

 nautUoid Enclimatoceras ulrichi White in the synonymy 

 of Hercoglossa danica (Schlotheim) . He considered 

 (1934, p. 1158) that the Midway was therefore of Cre- 

 taceous age, as the Danian was then generally regarded 

 as late Cretaceous. Gardner (1933, p. 92) first placed 

 the Midway group in the Paleocene, the lower Midway 

 (Kincaid) being considered Montain, and the Upper 

 Midway (Wills Point) correlated with the Landenian. 

 She stated (p. 99) that "The existance of marine 

 deposits of Danian age in either of the Americas has 

 not been established." Brotzen (1948, p. 32) considered 

 the Kincaid as of Danian age, and the Wills Point as 

 Seelandian. He also considered the lower Wilcox to 

 represent the Thanetian and younger stages. His 

 correlations were largely based on benthonic Fo- 

 raminifera although he mentioned that the Midway 

 "Globigeriuidae" occur in the lower Paleocene of 

 Sweden. 



Wilcox Group 



The Wilcox group is recognized by the U. S. Geologi- 

 cal Survey (Wihl^arth, 1938, p. 2333) to be of lower 

 Eocene age, and to designate "deposits overlying the 

 Midway and underlying the Claiborne in the Gulf 



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