IN THE UPPER KIO GRANDE EMBAYMENT IN TEXAS. 67 



quarried on Pinto creek at the crossing of the Southern Pacific 

 railroad, and also at Fort Clark in the west bank of Las Moras 

 creek. The limestone ledges are quite often separated by seams 

 of greenish gray clay, measuring from a fraction of an inch to 

 two or three feet. Upward these clayey strata increase in thick- 

 ness, and the formation terminates with alternations of clays 

 and strata of limestone. 



Area of Outcrop. 



The outcrop of the Austin chalk covers a comparatively wide 

 belt of land, which extends from the Rio Grande below the mouth 

 of Sycamore creek and eastward into Uvalde county. 



We find this formation on both sides of Pinto creek from the 

 southwest boundary of the company's lands to north of the 

 Southern Pacific railroad. It is the bed-rock underlying most of 

 the lands ■ drained by Cow creek and Tequesquite creek and 

 extends to the east of Las Moras creek. It covers the south 

 half of the Meliton Valdez grant, nearly all of the Dolores Soto 

 De Eeales grant, and all the land between Brackett and Spofford 

 Junction. From here the area of this formation continues east- 

 ward with decreasing width north of the Anacacho mountains. 



The upper hundred and thirty feet of the Austin chalk consist 

 of a series of alternations of white limestone ledges with strata 

 of clays and marls. These make a transition to the overlying 

 formation, which consists of clays and marls exclusively. They 

 were seen on Tequesquite creek, from its mouth to a mile and a 

 half above this, and also on Las Moras creek, in its lower course. 

 They are also exposed at a point a mile and a half northeast of 

 Spofford Junction, in Lindsaj' creek, and at several points on 

 both sides of the railroad bridge across Elm creek at the west end 

 of the Anacacho mountains. I here append a section of these 

 beds as thej^ were measured on Tequesquite creek. 



Section of the Upper Part of the Austin Chalk on Tequesqdite Ceeek. 



Thickness 

 in feet. 



7. Limestone 7 



6. Shale 17 



5. Thin ledges of limestone with some seams ot shale 6 



4. Stony marl with bands of limestone containing Gryphaea 



aucella 13 



