462 E. T. DUMBLE PROBLEM OF TEXAS TERTIARY SANDS 



outcrop of shales carrying such Yegua forms as Pleurotoma terebrifor- 

 mis, Marginella semen, and Corhula oniscus}'^ Half a mile below this 

 Veatch found a blue fossiliferous clay, which yielded ''a rather extensive 

 Jackson fauna, including Umlrella planulata and many large Capulus 

 americanus." ^~ Outcrops of overh'ing beds seen do^\'n the river seem to 

 be principally of clays and sandy clays. North of Anthonys Ferry these 

 clays are succeeded by the Grand Gulf or Catahoula sandstone, giving 

 the Jackson outcrop a width of between 3 and 4 miles on the Sabine. 



According to Baker and Suman, the northern limit of the Jackson, on 

 the line of the Santa Fe, is not clear, but is probably near Rush or be- 

 tween Rush and Bronson. The Jackson-Catalioula contact is Just south 

 of Brookeland. No fossils were found in this section. 



From the valley of Ayish Bayou Avestward the base of the Jackson was 

 more easily determined by reason of the occurrence of a series of dark 

 clays with greensand and calcareous concretions carrying fossils. The 

 line thus given crosses the St. liouis & Southwestern Railway north of 

 White City, the Angelina River 2 miles north of Caddell, follows the 

 line of the St. Louis & Southwestern Railway from Monterey to Donovan, 

 and crosses the Texas & New Orleans Railway just south of Prestridge 

 and the Houston, East & West Texas Railway in the vicinity of Diboll. 

 In the area east of the railway the general section of the Jackson from a 

 number of sections and traverses of Baker and Suman shows : 



At the base are greenish clays and sandy clays with some sand and 

 ffreensand, which are iron-stained. These weather dark brown and carrv 

 calcareous concretions. The concretions contain more or less sand and 

 greensand, are geodic in places, and they carry Jackson invertebrate 

 fossils and remains of plants. These are overlain by grayish browai, sandy 

 clays with seams of sulphur, which are followed by buff, sandy clays 

 with plant fragments, and gray drab clays with gypsum and sulphur. 

 Excellent exposures of these beds are found around the to^wTi of Caddell, 

 San Augustine County, and that name is proposed for this stage. 



Overlying these there is a series of lignitic or carbonaceous chocolate 

 clays and sands, with which are interbedded light-brown sandstones with 

 a porcelaneous cement, and coarse-grained gray sandstones which are 

 sometimes quartzitic. In the vicinity of the Angelina River and else- 

 where thin beds of lignite are found. 



The upper beds are of light greenish sands and carbonaceous sandy 

 clays stained with limonite and weathering into badland forms, capped 

 by dark-brown, sandy carbonaceous shales with plant fragments, selenite, 



3" U. S. Geological Survey Water-supply Paper No. .335, plate iv. 

 *' Geol. Surv. Louisiana, 1902, pp. 131-132. 



