55° THE JOURNAL OF GEOLOGY. 



by the lime is the small cauliflower-like concretions which abound 

 in certain beds. Gypsum crystals are also plentiful. 



In areal distribution the Basal clays are principally found 

 north of the Colorado river, and, although a few localities are 

 known south of that stream, the beds are, for the most part, 

 obscured by overlap. 



Typical exposures of the beds can be found in the vicinity of 

 Elmo, Will's Point, Tehuacana, and on the Rio Grande near the 

 Maverick-Webb county line. 



The fossils, which occur in pockets, have been determined by 

 Harris, who assigns the beds to the horizon of the Midway stage 

 of Alabama. Characteristic fossils are : 



Ostrea pulaskensis Har., Ciicidlcea macrodo?ita Whitf., Yoldia 

 eborea Con., Crassatella kennedyi Har., Pleurotoma ostrampis Har., 

 Volutilithes rugatus Con., V. limopsis Con., Pseudoliva unicarinata 

 Aid., Aporrliais gracilis? Aid., Enclimatoceras ulrichi White. 



Lignitic Beds. — These beds are composed, for the most part, 

 of siliceous sand of various colors, usually much cross-bedded, 

 micaceous and often containing specks or grains of glauconite. 

 Clays of various colors occur, laminated, as interbedded and 

 interlaminated sands and clays, and in massive beds. Lime is 

 present in the form of nodules, concretions and beds of siliceous 

 limestones. Gypsum is also found in places. Brown coal and 

 lignite beds, varying from a few inches to ten and twelve feet in 

 thickness, are of frequent occurrence, and traces of oil and gas 

 are found. Silicified wood is common. Iron occurs in the form 

 of pyrites, and also in nodules, strings and small seams of clay 

 ironstone. 



The upper portion of the beds is composed of a series of red 

 and white sands and white clays — the Carrizo sands of Owen 

 and Queen City beds of Kennedy. 



The lignitic beds are well marked from the eastern limit of 

 the state to the Rio Grande, forming, as a usual thing, gently 

 rounded hills covered with forests of oak. Typical exposures 

 may be found at Athens, Calvert Bluff, Rockdale, Lytle, Carrizo 

 Springs, etc 



