ECONOMIC GEOLOGY 
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Fie. 63.—A-]. CoMPARATIVE OILFIELD SECTIONS. 
(a) An anticlinal structure with the oil (solid black), floating on the water 
in the water-bearing oil bed, W, and enclosing above it the 
natural gas (dotted). 
(b) An oil well in a synclinal draining lenticles of sand as at the Florence 
Field, Colorado. 
[Description continued on opposite page.