Section of older Tertiary formations in Arkansas, Louisiana, and eastern Texas. 



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Arkansas and Louisiana. 



Formation. 



Fleming clay. 



Catahoula formation. 



Vicksburj' limestone. 



Jackson formation. 



Cockfield forma- 

 tion. 



St. Maurice for- 

 mation. 



Wilcox formation. 



T3 



CI 



Midway formation. 



Thickness 

 (feet). 



260 



1,000-1,200 



100-200 



200-550 



300-390 



200-500 



400-500 



20-260 



Character. 



Green calcareous clays, with a few brack- 

 ish-water fossils. 



Near-shore deposits; sandstones, occa- 

 sionally quartzitic, and green clays, 

 with fresh-water shells and land plants. 



Limestones and calcareous, somewhat 

 lignitiferous clays, containing marine 

 shells. 



Highly fossiliferous shallow-water marine 

 sandy calcareous clay. 



Lignitiferous sands, and 

 clays, with plants and 

 occasional beds of ma- 

 rine shells. 



Fossiliferous sandy clay, 

 containing shallow- 

 water marine shells. 



Lignitiferous sands and 

 clays, with land 

 plants. 



Landward 

 these forma- 

 tions merge 

 into lignitif- 

 erous sands 

 and clays 

 without dis- 

 tinctive ma- 

 rine fossils. 



Limestone and black calcareous clays. 



Beds separated by a pronounced break 

 in the fauna, which is concurrent with 

 an erosion unconformity now traced 

 from the Carolinas across Texas. 



Eastern Texas. 



Formation. 



Fleming clay. 



Catahoula sandstone. 



Jackson formation. 



Yegua formation. 



Cook Mountain formation . 



Mount Selman formation. 



Wilcox formation. 



Midway formation. 



Thickness 



(feet). 



100^00 



100-300 



50-60 



500-600 



200-100 



100-200 



500-800 



100-200 



100-200 



Character. 



Gray, white, and bluish-white bedded calcareous clays, with numerous small concre- 

 tions of lime; occasional lenses of sand. 



Hard blue semiquartzitic sandstones. 



Calcareous blue clays of marine origin developed in Sabine, San Augustine, and 

 Angelina counties only. Farther west this interval is occupied by the Catahoula 

 sandstone, which passes progressively lower in the column until it includes rocks 

 of Claiborne age. 



A very persistent series of gray fossiliferous sandstones, the Wellborn beds of Kennedy, 

 forms the base. 



Green calcareous clays with concretions of selenite; occasional lenses of sand and 

 lignite; possibly also occasional lenses of fossiliferous clays. 



Lenticular masses of yellow sand and clay; occasional lenses of green calcareous 

 glauconitic fossiliferous marl; occasional fossiliferous calcareous concretions, beds 

 of lunonite and lignite. 



Red ferruginous indmated and probably altered greeni sand, lenses of lignite and clay, 

 beds and concretions of limonite. 



Palustrine phase, consisting of white porous, loose, water-bearing sands (the 

 Queen City beds of Kennedy). 



Lignitic beds, consisting of lenticular masses of sand, clay, and lignite. Clays 

 are leaf bearing and in places-carry crocodile teeth; large concretions, some 20 

 to 30 feet in diameter, of hard, flintlike sandstone are especially characteristic . 



Marine phase, consisting of calcareous glauconitic fossiliferous marl, alternating 

 with beds of sand, clay, and lignite. Exposed only on Sabine River; does 

 not outcrop in the central Coastal Plain region, the Wilcox being there repre- 

 sented by the palustrine phase only, into which the marine phase grades. 



Palustrine deposits consisting of lenticular masses of sand, clay, and possibly lignite, 

 with indurated fossiliferous concretions. This member simulates in composition 

 the basal member of the overlying Wilcox formation. 



Black and blue fossiliferous shales, etc., of distinctly marine origin. 



<» The Jackson, Claiborne, and Wilcox, which are fossiliferous and distinct in central Louisiana, grade toward the north into lignitiferous beds containiag no distinct fossils. In northern Louisiana and southern Arkansas the 

 fossiliferous Jackson limits this lignitiferous complex above. Still farther north, however, the Jackson also grows lignitiferous and merges with the rest. The Midway, likewise, in the upper embayment region shows a decidedly 

 lignitiferous tendency and may in places merge with the lignitiferous time equivalents of the other Eocene beds. 



48011°— 12. (To face page 724.) 



