30 



LOWER EOCENE FLORAS OF SOUTHEASTERX N'OHTIf A:MERICA. 



River in Sabino (\iunty, Tex., unci Sabiue 

 Pai"ish, La. The.'^e outcrops also represent but 

 a part of tlie Wilcox as at present deliniited. 

 ■'Sabine River or Timber bolt beds" had also 

 been previoush* used by Peiu'ose in 1S90 for 

 dept)sits in eastern Texas that included niate- 

 riiUs of Claiborne and Jackson as well as Wilcox 

 age. The same year the term Wilcox was used 

 in a paper by Crider and Johnson ' on the 

 underground waters of Mississippi. Since that 

 date the more consistent supervision of the 

 committee on geologic names of the United 

 States Geological Survey has caused the general 

 adoption of the term Wilcox for this group of 

 deposits, from their fidlest and most varied 

 development m Wdcox County, Ala. 



FAUNAS. 



The Wilcox marine faunas are kno\ra only 

 from the seaward deposits of tliis age in south- 

 ern ^Mabama, in the eastern Gulf area, and in 

 northwestern Louisiana and along Sabme 

 River, in the western Gulf area.- The following 

 brief accoimt of the general character of these 

 faunas and their relation to the sediments is 

 based on the Alabama section and is followed 

 by a brief synopsis of the animal remains 

 fomid in the upper embayment region. The 

 paleozoologic data relatmg to the Alabama 

 section were compiled and interpreted by Dr. 

 J. A. Gardner, of Johns Hopkins LTniversity. 



The Wilcox moUuscan fauna is rather monot- 

 onous in general aspect, in spite of the four 

 faunules that have been differentiated. Prob- 

 ably the most important factor in determinuig 

 the general character of the marine moUuscan 

 life in an area where long time intervals, 

 range in latitude, and marked climatic changes 

 are ehminated is the depth of the water. The 

 Wilcox sea seems to have been quite miifornily 

 shallow from its opening to its close. At no 

 time is it at all probable that the depth ex- 

 ceeded 25 fathoms. The minimum depth is 

 indicated by the constant jiresence of Can- 

 ccllaria, Ostrea, Corbula, Pholas, and the like, 

 the maxinuun depth by the relative abundance 

 through the wholes Wilcox interval of the 

 larger univalves chiefly characteristic of the 

 sublittoral zone. There is no evidence that 

 the slight change in the character of the sedi- 



' Cridcr, A. F., and Johnson, L. C, U. S. Geol. Survey Water-Supply 

 Paper 159, p. 9, 1906. 



2 A small faunule has recently been discovered in MLssLssippi by 

 E. N. Lowe. 



nients during Baslii time involved any per- 

 ceptible deepening of the waters, and it is 

 mucli more probable that changes on the land 

 were the determining factors. The Hatche- 

 tigbee check lists, indeed, offer the only evi- 

 dence of any modification of the depth suffi- 

 ciently pronomiced to be reflected in the fauna. 

 The httorid fades is so much more prominent, 

 relatively, m this final epoch of Wilcox time 

 and the sublittoral facies so much less promi- 

 nent that a considerable shallowing may be 

 safely postulated. 



Tlie later faunal studies of the Wilcox as a 

 rule have been desultory or little more than 

 compilations from the work of the earlier inves- 

 tigators, particularly from Com-ad and Lea. 

 Harris, in his "Lignitic stage, "^ makes the 

 most ambitious attempt at a monographic 

 study. His paper iiears many of the marks of 

 rather hurried and superficial work, but he 

 does bring together in a fairly satisfactory 

 manner the results ah-eady obtamed, and his 

 mistakes, though rather numerous, are so 

 obvious that they are not misleading. .Ud- 

 rich has added very materially to the knowledge 

 of the faima in numerous short articles pub- 

 lished from time to time.* In one of his 

 longer papers^ he gives some check hsts 

 which, though published in 1886, include the 

 majority of the species thus far described. 

 The work on the undertying Midway and over- 

 lying Claiborne fatmas is even more fragmen- 

 tary and unsatisfactory, so that altliough the 

 Wilcox is recognized by both the paleozoolo- 

 gist and the stratigrapher as a clearly differ- 

 entiated group, comparative figures would not 

 afford satisfactory evidence of the differentia- 

 tion, as their percentage of error woidd be too 

 high. The literature of the formational fau- 

 nules, though meager, is, however, consistently 

 meager, and tables can be dra^vn up and com- 

 putations made which, though far fi\)m being 

 entirely accurate, yet convey a general im- 

 pression which is on the whole not misleading. 



The Nanafalia MoDusca recorded in the 

 literature constitute an ill-defined group of 

 a])out forty species, the denizens apparently 



' Harris, G.V., Bull. Am. Paleontology, vol. 2, pp. 195-294, 1897; idem, 

 vol. .i, pp. 3-128, 1899. 



' -Mdrich, T, H., Cincinnati Soc. Nat. Hist. Jour., vol. 8, pp. 145-153, 

 1885; Bull. Am. Paleoiitolocy, vol. 1, pp. 55-84, 1S95; idem, vol. 2, pp. 

 169-192, 1S97; idem, vol. 5, pp. 1-24, 1911; Nautilus, vol. 11, p. 27, 1897; 

 idem, vol. 11, pp. 97-98, 1898; idem, vol. 17, p. 19, 1903; idem, vol. 21, pp. 

 8-11, 1907; idem, vol. 22, pp. 74-76, 1908. 



' Alabama Geol. Survey Bull. 1, pp. 7-60, 1886. 



