4 



SHORTER CONTRIBUTIONS TO GENERAL, GEOLOGY, 1919. 



Juglans offers but slight evidence either for 

 or agiiinst the Cretaceous or Eocene age of the 

 deposits, but the species of both Flex and 

 Oreodaphne are decisively more modern in 

 their affinities than any Cretaceous forms 

 known to me. Moreover, the present small 

 flora lacks altogether the commoner Upper 

 Cretaceous dicotyledons, some of which would 

 almost certainly be present had the deposits 

 been accumulated during the Upper Cretaceous 

 epoch. I conclude from these facts that this 

 flora is of early Eocene rather than of late 

 Upper Cretaceous age. 



The question of the exact horizon in the 

 known Eocene with which these tuffs should 

 be correlated is, in the absence of more exten- 

 sive collections, more or less debatable. It 

 will be seen from the accompanj'ing table of 

 distribution that two or possibly three of the 

 species, namely, Sahalites grayanus, Juglans 

 rugosa, and Asimina eocenica (?), are present 

 in the flora of the Raton formation of the 

 southern Rocky Mountain region and that 

 these same three species are also present in 

 the Denver formation of Colorado. Asimina 

 eocenica occurs in the Midway ( ?) formation of 

 the Texas Coastal Plain, and both Sahalites 

 grayanus and Oreodaphne pseudoguianensis are 

 common in the deposits of the Wilcox group 

 in the Mississippi embayment. The two last- 

 named species are among the commoner 

 species in the Wilcox flora, and the Sahalites 

 is found at many localities and horizons in 

 beds of Wilcox age. Both occur along the 

 western shores of the Wilcox Mississippi 

 embayment, and Sahalites has been found 

 in beds of this age in western Texas. It is 

 well recognized by most paleontologists that 

 the commoner and more widely distributed 

 forms of a flora or a fauna are less useful in 

 critical comparisons than the less common 

 forms— that is to say, the less common forms 

 have a more precise value, as the commoner 

 forms generally range through a longer period 

 of time. 



This fact and the further fact that only 

 these two of the nearly 350 known Wilcox 

 species have been found in the tuffs of the Ba- 

 rilla Mountams, whereas one of a known 

 Midway (?) flora of but 10 species occurs in 

 the still smaller flora from the Barilla Moun- 

 tains, indicate very strongly that the latter 

 ■flora should be correlated with the Midway ( ?) 



flora. All the species of both floras are 

 dicotyledons. The fact that half of the six 

 known species from the tuffs are found also 

 in the Raton and Denver floras strongly 

 reinforces this conclusion, for in a detailed 

 comparison of these floras with that of the 

 Wilcox, I have given the evidence for consid- 

 ering them as approximately synchronous 

 and older than the Wilcox flora. ^ 



I conclude, therefore, that the basal tuffs 

 in the Barilla Mountains are post-Cretaceous 

 and pre- Wilcox in age and that they and the 

 volcanic activity which they represent were 

 probably contemporaneous with the floras 

 and similar volcanic activity reflected in the 

 Raton and Denver formations and elsewhere 

 in the Rocky Mountain region. 



Range of fossil plants found in the tuffs of the Barilla 

 Mountains, Tex. 









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a 



OS 







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a 







c 



+j 



s 







^ 



CS 



«+i 



p. 







a 



^^.^ 



3 







y^ 



c— 



















,p^ 





>> 



tCi 





^ 



© 



<A 







c 



> ■ 



^ 



8 





-is 



C 



T3 







C3 



0) 



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rt 



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Sabalites gravanus 



Y 



X 





X 



Geonomites visianii 











Juglans rugosa 



X 

 ? 



X 







Asimina eocenica 



X 



X 





Ilex barillensis 











Oreodaphne pseudoguianensis . 







X 











SYSTEMATIC DESCRIPTIONS. 



Phylum ANGIOSPERMOPHYTA. 



Class MONOCOTYLEDONAE. 



Order ARECALES. 



Family ARECACEAE. 



Genus SABALITES Saporta. 



Sabalites grayanus (Lesquereux) Berry (?), 



Plate I; Plate III, figure 5. 



Sahul grayana Lesquereux, Am. Philos. Soc. Trans., vol. 

 13, p. 412, pi. 14, figs. 4-G, 1869. (Not Lesquereux, 

 1871, 1874, 1876, 1878, or Knowlton, 1900.) 



Sahalites grayanus (Lesquereux) Berry, U. S. Geol. Sur- 

 rey Prof. Paper 91, p. 177, pi. 12, figs. 1-3; pi. 14, 

 fig. 1, 1916. 

 Knowlton, U. S. Geol. Survey Prof. Paper 101, p. 

 288, 1918. 



Flabcllaria eocenica Lesquereux, The Tertiary flora, p. 

 Ill, pi. 13, figs. 1-3, 1878. 



1 Berry, E. W., U. S. Geol. Survey Prof. Paper 91, p. 148, 1916. 



