IN THE UPPER RIO GRANDE EMBAYMENT IN TEXAS. 95 



A riliable well man, who has had the best opportunities to keep 

 informed on the yield of the wells in the Carizzo Sprino-s basin, 

 gives the information that the head of most of the wells has been 

 reduced, and. he estimates that on an average the head has gone 

 down twenty five feet since the flow was first tapped. \Yhether 

 there is a perceptible increase of droughty conditions in the Cha- 

 parrosa, Palo Blanco, and Gato Creek pastures is not known, 

 but it is to be expected that a greater part of the rainfall on 

 these lands will be lost to the surface and to the vegetation, and 

 will more rapidlj' than before sink to replenish the lowered head 

 of the ground water tapped b}' the Carizzo Springs wells. 



At the present time wells are permitted to flow to waste 

 without restriction. Economic considerations suggest prompt 

 ligislation to prevent this senseless waste. It will necessarily 

 reduce the area of irrigable lands. It is clear that the loss will 

 first affect those lands that lie toward the periphery of the basin. 



GAS AND OIL. 



The inquiry regarding the probable quantity of natural gas 

 in the country southeast of Eagle Pass resolves itself to a ques- 

 tion of geologic structure. The history of the well made some 

 years ago shows that gas was present under high pressure, and 

 the only doubt there can be as to the existence of commercial 

 quantities is as to the size of the reservoir which was then tapped. 

 To estimate this factor the structure of the formations was made 

 out in as much detail as was possible. The results of this study 

 have been given in the description of the structure. 



Natural gas occurs in folds where clay or shale or other im- 

 pervious strata form what we may call inverted troughs, or anti- 

 clines that prevent the accumulated gas from escaping upward. 

 A few instances have also been known where gas has accumulated 

 against a shoulder on an inclined stratum of impervious cover, a 

 so called arrested monocline. In every case the gas is held in 

 some porous rock. 



In the wells made on section 116 in block 6 the gas was found 

 in a sandstone that measured 57 feet in thickness. The whole 

 section of the well as given to me by Mr. W. L. Evans, is as below. 



Section op the Gas Well on Sdrvey 116, Block 6. 



Thickness 

 in feet. 



26. Yellow Clay 10 



25. Hard rock 4 



