10 



LOWEK EOCl.NK IM.OKAS OF SUL'TIIEASTERX XDRTII AMERICA. 



intollisent work. The initial Tppcr (Yotacoous 

 deposits ill this area, represented by tlie Wood- 

 bine sand of northeastern Texas and the Tus- 

 caloosa formation of northeastern Mississippi 

 and western and central Alabama, have fur- 

 nislieil an abundant flora, which 1 have re- 

 cently monographiMJ. 



The succeeding Eutaw formatit)n or its 

 equivalents' has furnished a considerable flora 

 in central Alabama and western Geor<j;ia, chiefly 

 from its basid beds. The Eutaw formation is 

 succeeded by mor(> than 2,000 feet of marine 

 strata, represented by the Selma and Ripley 

 formations or their equivalents, which are 

 practically without plant remains. The Selma 

 is a lithologic rather than a chronologic unit 

 and represents an immense deposit of argil- 

 laceous chalk in a region where at that time 

 terrigenous materials appear to have been re- 

 duced to a minimum. This in a measure 

 accounts for the absence of fossil plants, al- 

 though the waters are known to have been 

 shallow, for certainly none have ever been dis- 

 covered. I have never seen the trace of a leaf 

 impression or a piece of petrified wood, and even 

 small lignitized sticks are extremely rare. The 

 Ripley deposits at many places exhibit the 

 appearance of near-shore sediments of terrig- 

 enous material and are commonly somewhat 

 carbonaceous, but they have not yielded a 

 representative flora. In western Georgia and 

 in western Tennessee, where they most mark- 

 edly show a shallowing of the Cretaceous sea, 

 some few determinable plants liave l)een found. 

 These plants show some aflinities with those of 

 the upper part of the Montana group of the 

 Rocky Mountain ])rovince but not the slightest 

 hint of Laramie adlnities. The conclusion 

 seems reasoiial)I(', in spite of the negative char- 

 acter of the evidence, that the Laramie flora is 

 unrepresented in southeastern Xortli America. 

 In otlu^r words, the emerged area in this region 

 available for study at the present time was also 

 above the sea during at least a j)art of the time 

 when the Laramie deposits were being laiil 

 down in the Rocky Mountain province. This 

 fact is of greatest importance, for lliough there 

 is an evident physical break between the Rip- 

 ley deposits and those of the Midw.iy, this 

 break does not show intrinsic evidence of any 

 great magnitude. The faunas, however, which 

 are so much more representative^ than the 

 floras in both the Ripley and tiie Midway, are 



decidetUy difl'crent, and the little floral evi- 

 dence available indicates a very great floral 

 change between the Ripley and the Midway. 

 If there were no corroborative evidenc(\ though, 

 as I have just stated, there is considerable, I 

 would be obligetl to predicate an interval of 

 great magnituile to account for the evolution 

 and intermigration of floras which intervened 

 between the Ripley and (lie earliest plant- 

 bearing Eocene. 



There is then little in common lietween the 

 Midway (?) flora of Earle, Tex., and the Cre- 

 taceous flora. The genera Ficus, Platanus, 

 Cinnamomum, Asimina, and Laurus occur in 

 both, but they are all long-lived genera, which 

 appear at the base i>f the Upper Cretaceous 

 and continue to the present time, and all but 

 the genus Asimina have a very large number 

 of species. None of these Midway ( ? ) .species 

 occur in the Cretaceous of this or any other 

 area, in spite of the fact that both the L^pper 

 Cretaceous flora in this area as woU as that of 

 the Midwaj' (?) contain plants of similar low 

 coastal habitats and warm humid climatic 

 conditions. 



Only 2 of the 10 Midway (?) species are new, 

 and the genera to which they are referred are 

 not even represented in described Cretaceous 

 or Eocene floras. The other S species have 

 been found also in other places. The following 

 species are found in the overlying deposits of 

 the Wilcox group: Ficus denveriana, Ficus 

 sp., and Terminalia Tiilgardiana. The follow- 

 ing species occur in the Raton formation of the 

 Raton Mesa coal field in Colorado and New 

 Mexico: Ficus occidentalis, Ficus denveriana, 

 Platanus aceroidrs latifolia, and Tcrminnlia Iril- 

 f/ardiana. Five of tlie 8 species or ."JO per cent of 

 the known Midway (?) flora occur in the Denver 

 formation of the Denver Basin of Colorado. 

 These are Ficus denveriana, Ficus occidenfaJis, 

 Cinnamomum affine, Laurus wardiana, and 

 Asimina eocenica. This fact is of great ini])ort- 

 ance, as some geologists dispute (lie Eocene age 

 of the Denver formation, but no one can dis- 

 pute the age of the Midway (?) plants, which 

 are underlain l)y beds containing an uncpies- 

 lion)d)l(' marine fauna ami these outcrop on 

 tiie landward side of all the Tertiary leaf- 

 bearing dej)osits of southeastern North Ain(>r- 

 ica from Cii.'il 1 .'ilioorhcc ivivcr lo (lie mouth 

 of the Ohio and soulliwestward to the Rio 

 Grande. 



