1895.] NATURAL SCIENCES OF PHILADELPHIA. 143 



when compared with the enormous amount of such wood found in 

 the overlying sands. 7 '' 



With the exception of a narrow strip of country lying to the west 

 of a line drawn southward from the cretaceous border near Cooper, 

 in Delta County, and passing a few miles to the west of Sulphur 

 Springs, to the east of Emory, four miles east of Wells Point, be- 

 tween Mexia and Tehuacana and crossing the Brazos about a mile 

 north of the Milam Falls County line, the lignitic deposits occupy 

 the whole territory lying between the northern boundary of the 

 Marine beds and the southern line of the Cretaceous. Along the 

 eastern border of the State this area has a width of almost 160 

 miles but rapidly narrows in coming west. A line drawn across 

 these beds through Tyler, Mineola and Sulphur Springs, to the cre- 

 taceous border on the Sabine, near the south side of Delta County, 

 is only 75 miles and their exposure on the Brazos does not exceed 16 

 miles. 



Along the western side, these beds rest upon the basal beds of the 

 Texas Eocene, to the north they overlie and come in direct contact with 

 the cretaceous marls and on the east, as already stated, they pass into 

 Arkansas and Louisiana. To the south they are overlaid by the 

 Marine beds and altogether cover an area equal to at least one-third 

 of the whole Eocene tertiary in the State. 



The dip of these beds appears to be gently towards the southeast, 

 but the undulations referred to in the Marine beds also occur in the 

 lignitic, making many instances of apparent return or northwesterly 

 dips, and thereby making an effort to arrive at the actual thickness 

 of the beds through the measurement of the dip difficult and of only 

 doubtful accuracy. Fortunately, however, many deep borings have 

 been made at various points and from these we are enabled' to obtain 

 a fairly accurate measurement of the thickness. 



The topography of the country is simple. In the east the higher 

 elevations are those points capped by the lower beds of the overlying 

 Marine and which give the country a somewhat broken appearace. 

 Near the centre and westward the country becomes of a more uni- 

 form level. It is mostly covered with heavy growths of pine and 

 oak with mesquite bushes along the Brazos and through Robertson 



73 For connection between these beds and the Cretaceous see Science, Vol. 

 XXII, No. 565, Dec. 1st, 1893, p. 300. 



