TERTIARY. 433 



the falls, ten miles below Mount Blanco, there are numerous springs. Nearly 

 all the gulches that come into the main canyon from the westward have run- 

 ning streams in them of clear, pure water. There is water enough in the 

 canyon to irrigate large amounts of land if it was utilized in that way. At 

 places below the falls the water comes from the conglomerate found every 

 where below the sands of the Blanco Canyon Beds, but I tnink it is only 

 where there are fissures in the sandstone and conglomerate that such is the 

 case. Along the foot of the plains in the vicinity of Dockum there are sev- 

 eral springs of pure, clear water. 



I shall not attempt to determine the exact geological horizon of these beds 

 for the present, as sufficient data has not been obtained to enable me to do so 

 with certainty. 



LLANO ESTACADO. 



It has been supposed that the Staked Plains were of the same forma- 

 tion from one side to the other, and from the northern extremity at the Cana- 

 dian River to the Pecos. When one attempts, however, to correlate the 

 various reports that have been made from time to time, he will see at once 

 that either the observers were not competent to determine the question, which 

 is not so, or that the formation must be very different at different localities. 



Marcou saw the Llano Estacado on the north, and the upper beds of the 

 Plains he unhesitatingly pronounced Jurassic. Several parties have seen it 

 at Big Springs, and have called it Cretaceous. I have seen it in Tom Green 

 County, and am certain that it is Cretaceous there. I have also seen it at 

 Dockum, and am sure it is Tertiary ._ I have had fossils from Palo Duro 

 Canyon, and it is Tertiary there. I have traveled westward along the line of 

 the Texas and Pacific Railway from Big Springs, and am sure it is Tertiary 

 after getting upon the Plains west of Big Springs as far west as Dead Man's 

 Cut, where I think it is Cretaceous, the rocks there being almost entirely 

 composed of a small Gryphcea which has generally been referred to the species 

 pitcheri, yet it may be Jurassic. At the top of the Plains at Quito, the first 

 station east of the Pecos River, the strata are Triassic. Along the Pecos 

 River, southeastward as far as Devil's River, Shumard calls the upper part of 

 the Plains Creteceous; but it must be remembered that he put in the Marly 

 Clays of the Cretaceous the whole of the Red Beds of both the Permian and 

 Triassic, and it is only where he gives the fossils that are found in the strata 

 that one can be certain that his reference to the Cretaceous was correct. A 

 line of levels from the highest point on the Plains along the Texas and Pacific 

 Railway shows a regular dip to the eastward of about eight and three-fourths 

 feet to the mile in that direction, between Duro and Big Springs. Big Springs, 



