206 COAL FIELDS OF THE COLORADO RIVER. 



this is three inches of fire clay and a stratum of carbonaceous shale 1 foot 

 thick, with laminae of true coal. The shale is composed of clay, so filled with 

 plant impressions that their casts are found everywhere in the shale along 

 layers. Above this comes 25 feet of sandy shale — in places a true sandstone, 

 but in its upper and lower layers a true shale. 



At Milburrj, 12 miles northeast by north from this point, the following 

 section was obtained at Mr. Eubank's place, in a well 62 feet deep. Section 

 from below upward: 



Feet. In. 



1. Blue slates (very hard) Unexplored. 



2. Fossiliferous blue clay {Productus) 1 6 



3. " Horse back coal" (carbonaceous shale) 12 



4. Coal , 4 



5. " Horse back coal " (carbonaceous shale) 2 



6. Coal 4i 



1. Blue shales 12 



8. Shaly sandstone 16 



This coal is fully 75 feet beneath the limestone, while 12 miles south of 

 this the distance between the two is not more than 25 feet; yet they are the 

 same layer. I am convinced that the Milburn shales are thickening to the 

 northeast; and further evidence that the division as a whole is thickening in 

 this direction is found by following along the strike north of the river. 



At several places at Milburn and vicinity coal has been encountered in 

 wells, but nowhere in workable quantities. There is very little chance of 

 finding workable coal in the Milburn division south of the Colorado; but as 

 the formation is thickening to the northeast these beds north of the river 

 may contain coal of economic value. No prospecting has been done in this 

 section, and nothing can be said except that the surface indications are good. 

 Coal is certainly there, but in what quantities can only be told by the pros- 

 pector's drill. 



Above the. Milburn division is another great barren area, consisting chiefly 

 of limestone, which I shall call the Brownwood division. There is present 

 in these beds sufficient salt to render much of the water from deep borings 

 unfit for drinking purposes. The presence of salt is noticed in many of the 

 beds of the Carboniferous, but in this belt the salinity reaches a maximum, 

 being in some places almost a brine. 



The Brownwood division will average in width about ten miles, and has a 

 thickness of about 1300 feet of alternating sandstone and limestone. In the 

 northern part, in the vicinity of Brownwood, the sandstone is thicker and the 

 layers more numerous than south of the Colorado near Milburn. West of 

 Milburn, immediately over the Milburn shales, the Brownwood beds consist 

 of limestone, very sandy below, attaining a thickness of 100 feet, overlaid by 



