Much photogeologic interpretation depends upon late structural movement at the surface, either by rejuvenation or compaction around older structures. The Gulf Coast is one of the more active provinces from the standpoint of tectonism and compaction.

Actually, far more surface structure is mappable at the surface than many Gulf Coast geologists realize. By using special modern photography, and some of the more detailed geomorphic procedures that have been developed, much structural information can be obtained.

Detailed study of the air photos of the entire state of Louisiana, the Gulf coastal part of Mississippi and Alabama, and large parts of the Texas Gulf Coast have resulted in some interesting conclusions:

1. Far less distortion than can be measured with usual well control, or shallow seismic interpretation, is needed to create surface structural indications with the more sensitive geomorphic criteria.

2. A large percentage of the structural oil fields have recognizable surface features.

3. Some surface expressions associated with up- and down-to-coast faulting are not as expected from subsurface studies.

4. Geomorphically, an expression of the deeper causative structure commonly lies directly above on the surface, even in grabens and on the downthrown side of normal faults.

5. Special photography and more detailed and experienced interpretative effort are needed on the Gulf Coast.

6. Because the surface has been neglected by many explorationists, and because of the importance of inter-well control to prospecting, detailed photogeologic interpretation is an economical way to develop many prospect leads. Through better localization it substantially reduces seismic costs.

Subsurface-surface relations, and many air photo examples depicting the surface expression of pertinent oil fields and prospects, from both the Jurassic trend and the down-dip Gulf Coast, document the conclusions.

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