52 Cretaceous. 



Antonio river, at the town of the same name, the Guadalonpe at New 

 Braunfels, the Colorado at Austin, the Brazos at the falls of this river, 

 the Trinity below its forks, and reaching- from there to the Red river 

 in the same N. E. direction, divides the Tertiary strata, and the dilu- 

 vial and alluvial deposits (of the level and rolling part of the country) 

 from the Cretaceous and older formations (of the hilly and mountainous 

 sections) of Texas. The tr9,ct of level country which extends like a 

 broad belt along almost the whole coast of Texas, is diluvial and partly 

 alluvial in character. Its small elevation of a few feet onl}- above the 

 level of the sea, and its perfectly level surface, indicate, at once, the 

 recent origin of the soil. The fossil remains found in many places in 

 the deposits of clay and sand, prove their modern age still more con- 

 clusively. At the head of Galveston Bay, and near the town of Houston, 

 he found, at the height of 12 to 20 feet above the general level of the 

 Bay, large deposits of shells of Gnathodon, a bivalve mollusc, which lives 

 abundantly in the brackish waters along the coast of the Gulf of 

 Mexico, and in the Bay of Galveston, and a few oyster shells of the 

 common kind, but no shells different from those living in the Bay, 

 Everything tending to show that there had been no material change in 

 the climate, nor otlier circumstances since the period of these deposits 

 along the coast of Texas, except in the relative change of the level of 

 land and sea. To the diluvial period he referred the deposits of clay 

 and sand which form the banks of the Brazos, and probably all the 

 other large rivers of the country wherein he found the bones of the 

 Mastodon, Megalonyx, Tapir and other mammals. To the same period 

 he referred the deposits of gravel and sand, which form a broad belt 

 of barren or poor land covered with pine and post oak timber, in the 

 rolling or undulating portion of Texas, and extending from west to 

 east across a considerable part of the country. Following up the Co- 

 lorado from Columbus to Bastrop, or the Guadalonpe from Gonzales 

 to Seguin, we pass directly across this belt. The gravel is mostly 

 composed of pebbles of silex, evidentl}^ derived from decomposed Cre- 

 taceous strata. Within the limits of this gravel formation, fossil wood 

 of dicotyledonous trees, in smaller or larger fragments, is found almost 

 everywhere, and occasionally whole trunks of trees are met with. Near 

 the town of Caldwell, on the Upper Brazos, he found alternating strata 

 of brown ferruginous sandstone, and of dark-colored plastic clay, both 

 teeming with fossils belonging to the older divisions of the Tertiary 

 period 



The Cretaceous sti-ata which makes the most important part in the 

 geological constitution of Texas, and chiefly her upper hilly part, is 



