38 



LOWER EOCEXE FLORAS OF SOUTHEASTERN XORTH AMERICA. 



<;jroup; on the luulouhtod fjreat overlap of the 

 lower Claiborne in Georgia; on the very great 

 change in faunas, and especially in floras, in 

 passing from the Wilcox to the Clail)orne, for 

 of over 300 known species of Wilcox jjlaiits less 

 than half a dozen have been discovered in the 

 extensive floras of the Claiborne. Evidence of 

 the northward thinning of the Claiborne, indi- 

 cating deposition during transgression and n-- 

 treat of the watere is furnished by the sections 

 along Crowlej-s Ridge. Ark. The section on Boli- 

 var Creek containing Wilcox plants is discussed 

 on page 52. A considera])le l)ed of lignite lies 

 at or near the base of the Claiborne at numerous 

 localities in Ai'kansas, Louisiana, and Texas." 



The conclusion is reached that the relations 

 of land and water in this area between the end 

 of the Upper Cretaceous and the dawn of the 



SECTIONS IN MISSISSIPPI. 

 GRENADA, GRENADA COINTY. 



An abundantly fossiliferous outcrop in a 

 bluff on llie right l)ank of Bogue Kiver half a 

 mile al)ove the wagon bridge and 1 mile east of 

 Grenada, in Grenada County, Mi.ss., was discov- 

 ered by E. N. Lowe, State geologist of Mi.ssis- 

 si])pi. It is of considerable importance because 

 of its location so far south in theembavment area 

 and also because it is so near the top of the Wil- 

 cox group, for the overlying Claiborne outcrops 

 within a mile or two to the west, and the plant- 

 bearinn; horizon is hence within 100 feet of the 

 contact of the Wilcox and the Claiborne. The 

 whole section is about 1.50 feet in thickness, but 

 the upper and more sandy portion is mostly 

 concealed by slumping and vegetation. Along 



Figure L— Di 



ijn"am showing oscillations of the strand line iu the Mississippi embayment 

 during earlier Eocene time. 



Claiborne or middle Eocene were as shown in 

 figure 1. 



THE PLAXT-BEARING OUTCROPS. 



The individual sections in the Wilcox group 

 that are exposed to observation are nowhere 

 of very great thickness but hi many places 

 can be augmented by well records, and as the 

 attitude of the deposits is so uniform through- 

 out most of the region in wiiich tliey occur it 

 is possible to trace the different horizons from 

 place to place in spite of the very great lateral 

 variabilit}' of the materials. 



The following sections of plant-bearing out- 

 crops arc considered in geogi-aiiliic order from! lie 

 southernmost, in Mississippi, northward around 

 the head of the embayment and then southwest- 

 ward across Arkansas, Louisiana, and Texas. 



1 See Berry, E. W., Erosion intervals in the Eocene of the Mississippi 

 embayment: U. S. Geol. Survey Prof. Paper 95, pp. 73-82, 1915 (Prof. 

 Paper 95-F). 



the river the bluff shows about .30 feet of lami- 

 nated brownish, more or less indurated, sili- 

 ceous clay that contains white, somewhat mica- 

 ceous sand films, slightly iron stained and much 

 less micaceous than the material around Ox- 

 ford, Miss. The clays carry considerable com- 

 minuted lignite and abundant plant remams, 

 especially about 1,5 feet above the base. (See 

 PL VI, A, p. 44.) I have identified the follow- 

 ing 6.3 species, which I collected from this out- 

 crop with the assistance of Dr. E. N. Lowe: 



Anucardiles grcvillcafolia. 

 Ai)ot'yii()i)hylhiiii mississii)])iciisis. 

 Apocynopliylluiii Ki]iindil'olLum. 

 Aralia aceril'olia. 

 Aralia jorgcnseui. 

 Arlor-arpus puugeus (?j. 

 liaiiksia saffordi. 

 Jiiiiuclia greuadensis. 

 CiL'iioiuyces pestalozzites. 



