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Tyler); Tyler prairie, on the southeastern border; Nevill's and Mustang prairies, near the western limit. These prairies have a total area of approximately fifty square miles, and strongly resemble each other in soil and general structure. Other small prairies intervene between these, but are generally of very limited extent.

The chief streams are Cypress creek, San Pedro, Hickory and Camp creeks, and Cochino bayou, flowing eastward into the Neches river. Piney creek flows south through Trinity county, and finally empties into the Neches river. In the southern portion White Rock, with its tributaries, Box creek and Tantabogue creek, form the outlet for the drainage of an extensive area. Negro, Lost and Caney creeks, and Hurricane bayou, and the two Elkhart creeks, flow west into the Trinity river.

Throughout the central hilly region several of the higher points are locally known as mountains, the most pronounced of these being Cook's mountain and West mountain. Cook's mountain is a prominent feature of the landscape, rising about one hundred feet above Crockett, and having an elevation of about four hundred and sixty feet above sea level. This mountain rises with a gentle slope from the east and ends abruptly on the west and northwest. Its top is perfectly flat and covered with fragments of ferruginous material and fossiliferous altered greensand. The northwestern corner ends in a narrow peak about thirty feet wide, rising over one hundred and eighty feet above the level of the Hurricane bayou bottoms. From this point an extended view of several miles can be had of the lower level lands lying to the east, north and west. West mountain is the higher portion of the ridge separating the Hurricane bayou drainage from the Little Elkhart, and rises to an elevation of about four hundred feet. It is a sandy belt, covered with a conglomerate iron ore and ferruginous sandstone.

In the northeastern portion some of the high sandy hills have elevations of from five hundred and thirty to five hundred and fifty feet above sea level, Houston mound, the most prominent of them, having a still higher elevation.

GENERAL GEOLOGY.

The geological section of the county shows the Quaternary deposits to be spread over a greater part of the northern division to a greater or less depth, with a few isolated patches scattered throughout the southern portion. The general dip of the beds is in accordance with the Tertiary and later deposits of Eastern Texas—that is, from northwest to southeast approximately. Some local variations occur, but these are not generally to any great degree, and where such changes appear they are altogether due to some local cause—most of them to the erosion of underlying deposits or beds of sand. These sands are acted upon by the underground flow of water, which, finding its outlet in the numerous