The Azalea carbonate biogenic bank developed on a broad shallow shelf during early Strawn deposition. Study of cores and well cuttings defined 3 major facies. The "deeper water" micrite is dark brown with scattered crinoid fragments and was deposited in water from approximately 50 to 200 ft deep. The biogenic bank facies is composed of coarse fossil fragments including crinoids, Bryozoa, pelecypods, brachiopods, fusulines, and platey algae. The "sheltered" micrite is light brown with small fossil fragments consisting mainly of bivalves and Foraminifera deposited behind the bank.

Bank development was confined to the west edge of an Atokan structural terrace where oscillation waves were impinging upon the rising sea floor. Moderately high energy, shallow water and the associated supply of nutrients provided necessary ingredients for prolific growth of organisms which formed the biogenic bank.

Hydrocarbon production has been obtained from the bank over 13 mi of its length. Recently production has been extended 1 3/4 mi on the south end and 1½ mi on the north end. There is a good possibility that additional biogenic banks have developed on the broad Strawn shelf.

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