348 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213, 
vent its escape from the reservoir roek to the surface is found in the 
beds of clay and compact limestone which make up the "buried beds " 
described in the above section on stratigraphy. 
The structure of the Coastal Plain is not generally favorable for oil 
accumulation. The gentle southeastward dip of the beds does not 
appear to be sufficient for the easy migration of the oil to points of 
accumulation, and it is only where this uniform dip is interrupted by 
the dome-like structures mentioned above that accumulation has 
taken place. Hence the prospector should search for these favorable 
structures and while, as experience has shown, not all of them contain 
oil in commercial quantities, they afford by far the most probable 
localities for drilling. The elevations above the surrounding level 
plain which are depended on to indicate the presence of these favor- 
able structures are due to the continued action of the elevating force, 
whatever it may have been, down to a very recent date. Where this 
force has been most active and the elevation has been greatest, as at 
High Island and Damon Mound, no oil is found. It is quite possible, 
therefore, that there may be within the Coastal Plain similar struc- 
tures not marked by surface elevations, even more favorable to oil 
accumulation than any thus Car discovered. These can be revealed 
only by the drill, but a careful study of the arrangement of the known 
domes may afford valuable suggestions as to their location. 
The fifth condition favorable for oil accumulation, complete satura- 
tion of the strata with water, is probably very general in the Coastal 
Plain, but how much circulation this ground water has and what its 
effect on the accumulation of oil may be are poinls concerning which 
there are few data available 
THE OIL POOLS. 
The actually productive oil territory, so far as at present known, 
forms but an extremely small fraction of the area of the Gulf Coastal 
Plain. Excepting the Spindletop pool the limits of the productive 
territory are in no case defined wit li any degree of accuracy. The 
separate areas or "pools," as they are generally called, will probably 
be found to vary in size from 200 to 2,000 acres. In this respect the 
field differs widely from the Corsicana field of central Texas and from 
the great Appalachian field, where the pools are much larger, but 
where the oil is in smaller quantity and generally under less pressure. 
In this field productive territory has been developed at Beaumont, 
Sour Lake, Saratoga, and Jennings, while encouraging indications are 
found at Sabine Pass, Dayton, Columbia, Velasco, Anse la Butte, 
Vinton, and a few minor localities. 
Of these the Spindletop pool at Beaumont is by far the best 
known. Oil was discovered in the Lucas well in January, 1901, and 
within a year and a half there were 280 producing wells, and a large 
number of dry wells had been drilled outside of the limits of the 
