18 OIL FIELDS OF TEXAS-LOUISIANA COASTAL PLAIN, [bull. 312. 
UNDERGROUND CONDITIONS. 
Throughout this portion of the Coastal Plain the actual geologic 
conditions underground are unknown. Numerous shallow wells 
ranging from 100 to 300 feet in depth have been drilled for water. 
The drillers report rock in a number of these wells at 50 feet and then 
a mixture of rock, clay, and sand to the bottom of the wells. Few 
wells of greater depth have been drilled. Years ago the State made 
arrangements for the drilling of a number of test wells for water in 
this region and proposed to pay for these by granting sections of land. 
Under this arrangement one well was commenced at "Magueyes," on 
the eastern side of Hidalgo County, but to what depth it was drilled 
is unknown. The next deep well was drilled at Corpus Christi to a 
depth of 1,765 feet. This well gives a small flow of very disagreeable- 
smelling sulphur water. Several wells having depths ranging from 
500 to 750 feet have been drilled for water on the Santa Gertrudes 
ranch, in western Nueces County, and yield strong artesian flows. A 
well at Alice is reported to have a depth of 1,000 feet. Northward, in 
the gray sandstone regions, the public well at Tilden has a depth of 
GOO feet, giving a strong flow of brackish water with gas. This well 
was drilled in rock with thin partings of clay. Twelve miles south 
of Tilden, at Shiner's ranch house, a well 900 feet deep gives a small 
flow of strong salt brine. 
So far as our knowledge of the structure of this region goes, it 
appears that the Fayette sand si ones had formed the shore line for a 
considerable period and had been extensively eroded before the suc- 
ceeding beds were laid down. The evidences of unconformity are 
plentiful. The Pliocene Re}aiosa limestone lies high up on the hill- 
sides, and also appears to form ridges on the gray, sandy plain. This, 
it is true, would give these limestones a gentle dip of about 10 feet 
per mile, but as the surface relief is greater than that, much of these 
deposits must have been destroyed. Whether these Keynosa lime- 
stones ever formed the surface or floor of the plain, and the existing 
ridges are due to erosion, or whether they form the crests of small 
anticlines brought up by some earth movement, is not known. 
SECTION FROM PLEASANTON TO PALITO BLANCO. 
A generalized section across this portion of the Coastal Plain from 
Pleasanton to Palito Blanco shows the following beds, in descending 
order : 
Section of Coastal Plain from Pleasanton to Palito Blanco. 
1. Brown sands of Coastal Plain. 
2. Blue clays. 
3. White or lemon-yellow limestones. 
4. White, yellow, and brownish-yellow clays. 
5. Thinly bedded gray sandstones, with white and gray clays. 
6. Thinly bedded gray sandstones and gray clays. 
7. Marine fossiliferons brown sand, with more or less gypsum in crystals. 
8. Lignitic beds found in wells at Pleasanton. 
