1895.] NATURAL SCIENCES OF PHILADELPHIA. 101 



Brazos Counties than farther east. These are sometimes laminated 

 and crossbedded but the greater portion is structureless. They are 

 often saline, heavy incrustations of salt occupying the beds of 

 dry pools and are of frequent occurrence during the summer months. 

 In places they contain quantities of silicified wood of a dull, lustre- 

 less appearance, showing a strong contrast with the beautifully 

 opalized woods of the overlying Fayette sands. 



The lignite deposits of this division although well developed at 

 many points are not so extensive, or nearly so regular, as those of the 

 lignitic stage of the earlier Eocene. Most of the deposits range from 

 two to four feet, although from six to ten feet are by no means rare. 



Borings through these clays show them to have an aggregate 

 thickness of nearly 1,000 feet. A well at Lamb's Springs, in 

 Grime County, 999 feet deep passed through a series of clays, sands 

 and lignites the whole depth, and another boring at the Agricultural 

 and Mechanical College, five miles south of Bryan, in Brazos County, 

 reached the 900 foot mark before the drill entered the underlying 

 marine beds. 



On the Brazos River the contact between the overlying Fayette 



sands and these clays is seen on the south side of the James Hope 



Survey in a section showing: 



« 

 Gray sand and gravel 1 foot. 



Gray sand containing great quantities of silicified 

 wood. The w T ood is usually in large pieces — 

 four to six feet in length, and bleached white. 5 feet. 



Gray Indurated sand with ledges of soft sandstone. 10 " 



Gray sandstone jointed and thinly bedded, form- 

 ing base of Fayette sands 8 " 



Dark brown lignitic clay, showing yellow bands 

 from I to A inch in thickness and coated with 

 an efflorescence of sulphur, to water .... 20 " 



No. 5 corresponds to the upper brown clay of Prof. Penrose's 

 section of sulphur bluff in this neighborhood and a continuation of 

 the section will give: 30 



6. Lignite 1 foot. 



7. Gray sand • 1 " 



30 First Annual Eeport Geol. Survey of Texas, 1889, p. 54-55. 



