HAWORTH.] Detailed Geology of Oil and Gas. 173 
in determining the location of that unusually rich field. The in- 
clination of the rock bedding-plains need not be more than from 
5 to 10 feet to the mile, although they may be as great as 20 or 
30, or even 100 or 200 feet to the mile. The steeper the in- 
clination, naturally the narrower the productive area is likely 
to be, because with a rapid dip of the formations the pro- 
ductive sandstone soon would be carried so far beneath the 
surface that water is almost sure to be present. A study of 
the simple illustration, figure 5, will show one how we may 
have a series of wells close together, one a good gas-well, one 
an oil-well, and the other one filled with water. The proper 
way to consider this question is that all porous rocks are filled 
with water, with an occasional exception of a bubble of gas or 
oil being found in the water. This bubble may be small or 
large, even to many miles in horizontal extent. All too fre- 
quently, however, such a bubble is narrow and soon exhausted. 
So long as rains continue to fall on the surface and the water 
works its way downward, that long there will be a tendency 
for water to drive out all fluids of lighter gravity, and there- 
fore the water pressure will tend to drive both oil and gas up- 
ward and outward. The same agencies cause the water to fol- 
low the gas and oil as they become exhausted. 
It is easy to imagine certain variations from those given in 
figure 5, so that we may have a body of oil or gas in a sand- 
rock connected directly with a body of water at one side, the 
water shutting out the oil or gas from the drill-hole. Ex- 
hausting the water by pumping in such cases would allow the 
oil gradually to approach the well and ultimately develop into 
a reasonably good oil-well. This condition has been found in 
many places in different oils and likely will be found many 
times in the future. It is due to a certain combination of oil 
and water conditions with the well accidentally being drilled 
so as to hit the water near the oil bubble. | 
If the reader will recall what has been said about the irregu- 
larity of sandstone production on our present ocean beaches 
and will understand that all masses of sandrock, whether or 
not they are producers of oil and gas, were formed along old 
ocean beaches in the same manner, he will be able to under- 
stand some of the perplexing conditions found in many oil- 
fields. 
All anticlinal arches have been formed subsequent to the 
formation of the sand-beds. It is a mere accident, therefore, 
