42 GULF TERTIARY OF TEXAS. 



This is the first outcrop which has a Tertiary appearance. A quarter of a 

 mile below is a bluff fifty feet high of indurated sandy clay, containing mica 

 and ferruginous scales between the strata. Dip 1 degree south. One and a 

 half miles below are seen similar deposits, but with no fossils, and containing 

 numerous gray calcareous concretions with veins of brown crystalline calcite. 

 Two miles beyond this, on the Mexican side, is a bluff, a quarter of a mile long 

 and seventy-five feet high, of interlaminated gray sands and chocolate clays, 

 with sulphur and gypsum in places, and occasional ferruginous spots. Hard 

 gray clay ironstones with leaf impressions are also found. The sand beds 

 are from one to five feet thick, and the clay is in thin laminae. Dip undula- 

 ting from 1 to 5 degrees southeast. These bluffs have a decided Tertiary 

 appearance. The mica and black specks in the sand, the laminae of choco- 

 late clay, the presence of sulphur and gypsum crystals, all show a strong 

 resemblance to the Tertiary of East Texas. From here to the Hardin Ferry, 

 and thence to the mouth of the Cavezeras River, are seen similar strata, fre- 

 quently causing rapids where they cross the Rio Grande. In one place the 

 indurated bluffs encroach on the river until it narrows down to thirty yards. 

 Here the waters have cut a deep channel and rush through at a great velocity. 

 Frequently interbedded glossy brown ferruginous layers, one to two inches 

 thick, are found in the sandstone. Three miles below "the Hardin " is a bluff 

 sixty feet high composed of friable standstones, the harder and softer layers 

 blending into each other and occasionally showing ferruginous patches. Dip 

 1 degree south. For nineteen miles below this point we pass over identically 

 similar strata, frequently containing calcareous concretions one to three inches 

 in diameter. These contain seams of crystalline calcite, and are of a gray 

 color, weathering brown or red in concentric layers. 



At a point eight miles above the Texas town of Palafox, and on the Texas 

 side, the following section was seen: 



1. Siliceous sand, colored red, yellow, and purple in seams 40 feet. 



2. Light green clay, with specks of black mica 10 feet. 



In 2 was found the impression of a palm leaf, very similar to those found 

 at Palm Bluff, on the Colorado. The bed containing it is also very like those 

 of the " Fayette Beds" at that place. As true Eocene-Tertiary strata are 

 found below here, this bed must either not belong to the Fayette series, or 

 else it is an isolated deposit far inland from the westerly edge of the main 

 outcrop. Palafox is thirteen miles above the San Tomas coal mines and 

 directly opposite the Mexican town of Hidalgo.* The latter place is on a 

 ridge thirty to fifty feet high and a half mile long, composed of the same 

 sandstone as is seen above. Dip almost horizontal. 



*This town is not the Hidalgo in Hidalgo County; the latter is in Texas. 



