144 PROCEEDINGS OF THE ACADEMY OF [1895. 



County. Prairie conditions prevail over some areas but only to an 

 inconsiderable extent. 



Basal Beds or Wills Point Clays. 



These beds form the lowest deposits of Eocene age in Texas and 

 rest directly upon the marls of the Cretaceous. They correspond in 

 time with the Mathews Landing, Black Bluff and Midway sections 

 of the Alabama lignitic and Harris' Midway stage of the lower 

 Eocene. 



In Texas these beds are represented by a series of yellowish brown, 

 brown and bluish gray sands, yellow and blue laminated clays and 

 massive clays containing numerous boulders of silicious limestone 

 and two beds of white fossiliferous limestone. The yellowish brown 

 sand contains numerous boulders of calcareous sandstones and lime- 

 stone veined and streaked with calcite and enclosing occasional fossils 

 and the sands themselves also carry a few broken shells. White, 

 limy concretions and crystals of selenite are also numerous in some 

 of the clays. 



These beds have an aggregate thickness of about 260 feet and they 

 occupy a narrow strip of country lying between the Lignitic on the east 

 and the Cretaceous areas on the west. Their greatest width does not 

 exceed some 13 miles in the vicinity of Wills Point and gradually 

 narrowing to a point at each end. The greatest length from north 

 to south does not exceed 170 miles. 



The detailed information regarding these beds is meagre from the 

 circumstances attending their condition and the time spent in making 

 examinations. Their immediate contact with the overlying lignitic 

 deposits has nowhere been seen. Near Wills Point the upper sands 

 of the lower lignitic overlap for more than a mile and a half and on 

 the Brazos the contact is obscured by w T ide spreading deposits of river 

 alluvium and plistocene clays. The contact between the basal beds 

 and the Cretaceous marls appears about four miles west of Elmo. 

 In this region the dark blue laminated clays of the lowest Eocene 

 rests upon the bluish weathering yellow marls of the Cretaceous 

 Ponderosa beds. The section at this point shows : 



1. Brownish gray sands containing boulders of 

 limestone with thin seams of calcite and 

 occasional broken shells 25 feet. 



