STRATIGRAPHY. 13 



takes a long time on account of the currents in the rivers, and, consequently, 

 competition with railroads is impossible. The Sabine was formerly navigated 

 for three hundred miles from its mouth, while cotton boats capable of carry- 

 ing a thousand bales made regular trips up the Trinity to Green's Landing, 

 in the northwestern part of Anderson County. A small steam launch is also 

 said to have once ascended this river as far as Dallas. The Brazos was navi- 

 gated before the railroads came in up as far as the town of Washington, and 

 boats are said to have gone up even to Marlin Falls, a distance of six hundred 

 miles. The Colorado River has only been navigated in places. A small 

 steamer carrying cord wood once plied a portion of the river in the neigh- 

 borhood of Austin. A "raft" of drift timber at its outlet prevents the en- 

 trance of boats, and therefore prohibits any extensive shipping. 



The smaller streams, such as the Neches and Angelina, are navigable for 

 short distances above their mouths.* 



STRATIGRAPHY. 



East Texas proper, i. e., the region east of the Brazos, is underlaid mostly 

 by Tertiary strata, though to the northwest we come to Cretaceous beds, and 

 on the coast we meet Post-Tertiary clays. The line separating the Tertiary 

 and Cretaceous strata has not yet been accurately run, but points along it 

 have been determined and are sufficient to allow a general line to be drawn. 

 This line runs in a general southwest and northeast direction, crosses the Red 

 River west of Texarkana; thence proceeding southwest it interects the Texas 

 and Pacific Railroad near Elmo, nine miles west of Wills Point, and the Mis- 

 souri, Kansas and Texas between Corsicana and the Trinity River; it crosses 

 the Brazos in the northeast corner of Milam County; the Colorado ten miles 

 below Austin. Between here and the Rio Grande the boundary line has not 

 yet been run, but the first true Tertiary fossils found on that river, going 

 down stream from Eagle Pass, are met in the northwest corner of Webb 

 County and three miles below the Maverick County line, at a distance almost 

 half way between Eagle Pass and Laredo. The uppermost part of the Creta- 

 ceous and the base of the Tertiary strata are both composed of soft clay and 

 sand beds, which succumb readily to the weathering action of the atmosphere, 

 and consequently the line of separation is often impossible to locate exactly. 

 The uppermost beds of the Cretaceous in Texas and Arkansas are composed of 

 sandy and " glauconif erous " strata, sometimes reaching a maximum thickness 

 of three hundred feet. These have been termed the " glauconitic " division 

 by Hill.f They, vary in composition from beds of pure siliceous sand to beds 



* On the Rio Grande a steamer makes regular trips between Brownsville and Roma, and 

 tradition says that government supplies were once taken up as high as Laredo. 

 f American Journal of Science, Vol. XXXYIJI, December, 1889. 



