U. S. GEOLOGICAL SURVEY BULLETIN NO. 164 PL. III A. CRETACEOUS-EOCENE CONTACT ON THE FRIO RIVER, 2 MILES BELOW ENGELMANN'S RANCH SOUTHERN UVALDE COUNTY. The sandstone floor at the base of the bluff is Cretaceous; the middle and upper portions of the bluff areEocene.

U. S. GEOLOGICAL SURVEY BULLETIN NO. 164 PL. III
A. CRETACEOUS-EOCENE CONTACT ON THE FRIO RIVER, 2 MILES BELOW ENGELMANN'S RANCH SOUTHERN UVALDE COUNTY. The sandstone floor at the base of the bluff is Cretaceous; the middle and upper portions of the bluff areEocene.

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DEPARTMENT OF THE INTERIOR BULLETIN OF THE UNITED STATES GEOLOGICAL SURVEY No. 164
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