42 OTL FIELDS OF TEXAS-LOUISIANA COASTAL PLAIN, [bull. 212. 
The limestone found in the Velascowell at about 745 feet, where the 
gas flow was struck, is apparently closely allied with the limestone 
found in the Matagorda County well at about 900 feet, in which a 
similar flow of gas occurred. In both cases it caused the abandon- 
ment of the wells. A similar heavy flow of gas occurred in the Equi- 
table Mining Company's well at Columbia at a depth of about 600 feet. 
Little or no gas occurs in the wells at Damon Mound. 
DETAILED SECTIONS BETWEEN BRAZOS AND TRINITY RIVERS. 
In the region lying between the Brazos and Trinity rivers a new 
topographic feature is introduced. From the western boundary of 
the region discussed eastward as far as Galveston Bay the coast line 
is protected by a series of long, narrow islands, or keys, separated 
from the mainland by narrow, shallow lagoons. These lagoons show 
more or less of a bluff structure along their inner or landward shores. 
This shore bluff, beginning at an elevation of a few feet at Point 
Isabel, gradually increases in elevation until it reaches its highest 
point in the neighborhood of Corpus Chxisti. From that point the 
bluff lessens in height until it reaches the shore of Galveston Bay. 
On the cast side of the bay, in the neighborhood of East Bayou and 
up along the eastern shore to the mouth of Trinity River and Cedar 
Bayou, commences the low, flat sea marsh area which continues east- 
ward and forms an extended territory in the southern portion of 
Jefferson and Orange counties in Texas and Cameron and Vermilion 
parishes in Louisiana. 
In the same limits there are also numerous mound-shaped eleva- 
tions which may be in part remnantal and due to erosion and in part 
due to the uplifting of the underlying beds. The Sun Mounds in 
Waller County are representative of the first class, and Dayton Hill, 
Barber Hill, and Davis Hill probably belong to the second class. 
In its general features this portion of the country has the same 
characteristics as the counties lying immediately to the west of the 
Brazos. The general section shows the Fayette sands to comprise a 
series of graj 7 and yellow sandstones, more or less calcareous in some 
portions, and interstratified with coarse, j^ellow sand and beds of sili- 
ceous yellow limestones. The beds are somewhat lenticular in form 
and the material is very irregular in texture, often passing from a 
solid, close-grained sandstone to a loose, unconsolidated sand in a 
distance of a few hundred yards. 
The southern boundary of this series and its contact with the suc- 
ceeding Frio clays is often obscured by heavy beds of gravel which 
form a belt over 3 miles in width and 15 to 20 feet in thickness. 
This boundary passes across the counties of Grimes, Montgomery, 
and Walker in a general northeastern diiection from near Chappel 
Hill, in Washington County, passing Courtne} 7 and Anderson, in 
Grimes County, and crossing the Trinity near Riverside on the Inter- 
