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.