HAYES AND 
KENNEDY. 
DETAILED SECTIONS. 65 
1893 the black cherty gravel was passed at 200 feet. In the Lucas 
well and the Iliggins well No. 1 the gravels occur at 245 feet, in the 
Geyser Development well at 295 feet, and in the Tread way at 454 feet. 
Westward the Texas Gulf Coast Land and Oil Company passed 
through 40 feet of conglomerate at a depth of 360 feet. In the Bryan 
Heights well near Velasco, in Brazoria County, the gravels were 
reached at a depth of 735 feet. At Damon Mound the gravels are 
associated with shells at 171 feet in the Ilerndon well and at 255 feet 
in the Guffey No. 1, about a mile to the northwest. In this latter 
well they have a thickness of 18 feet, while in the Herndon well they 
show only 6 feet. The thickness shown in the Velasco well is over 10 
feet, but the actual thickness is not known. 
It appears from the above well records that throughout the whole 
of the Texas region these gravel beds are much thinner than in 
Louisiana. In the Texas wells they range from 10 to 26 feet, except 
in the Gulf Coast well as given above. 
At the time of the deposition of these gravels the land must have 
stood at a comparatively slight elevation above the level of the sea 
and have had only a moderate inclination seaward, since their dip as 
shown by the borings does not at present exceed 9 feet per mile. 
The determination of the age of these gravels and their correlation 
with similar deposits elsewhere are somewhat difficult, and involve 
questions which can not be definitely answered without carefully 
tracing the beds over extensive areas toward the northeast. What- 
ever their age, whether late Tertiary or early Pleistocene, they should 
probably be correlated with the Plateau gravels of central Texas and 
the Uvalde formation of southwestern Texas, as described by Hill, 
and with the latest episode of the Lafayette formation east of the 
Mississippi, as described by McGee, or, more properly, the earliest 
Columbia. Since these deposits of coarse material were probably laid 
down at the margin of a transgressing sea, they can not be regarded 
as strictly contemporaneous, except along lines parallel to the former 
sea margin. 
Like their associated overlying sand beds, the presence, thickness, 
and position of these gravels are of the utmost importance to the 
well driller. They are usually strongly water bearing, and the driller 
after water is almost certain to get a considerable supply when he 
reaches them. To the oil-well driller these gravels often offer a strong 
barrier to his further progress. The rotary method of drilling is not 
adapted to raising such heavy material to the surface, and more than 
one well has been lost because the driller was not prepared to handle 
this gravel when reached. Where the gravel beds are heavy the 
driving of the casing has usually to be resorted to. This entails con- 
siderable risk, and often the loss of the well by damage to the casing. 
Bull. 212—03 5 
