IN THE UPPEE BIO GRANDE EMBAYMENT IN TEXAS. 75 



far from the Olmos creek mines. Other explorations show that 

 this part of the section is variable. Numbers 4 to 16 inclusive 

 outcrop in the hills to the north of Eagle Pass on the west side of 

 the railroad, and numbers 17 to 20 were measured and traced for 

 sevei'al miles in the bluffs east of the railroad. Number 20 caps 

 the bluffs east of Eagle Pass. 



Thickness. 



No fast limits can be assigned to the three divisions of the 

 Eagle Pass formation. If we designate the lowest sandstone in 

 the above section (number 1) as the basal member of the coal 

 series and the uppermost clay (number 19) as its highest part, 

 we find that the total thickness is 372 feet. 



Distribution. 



The coal series are exposed in the valley of the Rio Grande 

 from some five miles below Eagle Pass to about three miles north 

 of the mouth of Olmos creek. The area of their outcrop forms a 

 belt about four miles wide, which follows the Olmos valley from 

 the points indicated on the river to about three miles north of 

 Olmos station (Thompson's ranch). Beyond this the belt turns to 

 the east around Chapotal hill and then to the southeast. The sand- 

 stones of the Eagle Pass formation are seen in Olmos Grande. 

 Olmos Ghiquito and in Chapotal creek. Again this belt turns east 

 and then northeast and north, as appears from exposures of soft 

 sandstones, carbonaceous clays, ferruginous concretionary ma- 

 terials, and silicified wood, such as characterize these sediments 

 north of Eagle Pass. Materials of this kind are met with on Sur- 

 veys 209, 186, 177, 178, 155 and 145 in block 7. Beyond this 

 the coal series has not been identified. Its sediments are in all 

 probability reduced in thickness farther east and go to make up 

 a part of the as yet unclassified complex presently to be described 

 as the Pulliam formation. 



The Eagle Pass Coal. 



I^hin seams of coal, measuring a few inches in thickness, have 

 already been noted In the sections of the Coal series. But neither 

 well records nor outcrops have so far shown more than one work- 



