A 550-ft continuous core from San Salvador allows detailed study of depositional and diagenetic facies patterns with depth. From the surface to about 25 ft, the rocks are oolites and oolitically coated intraclasts, cleanly washed and bedded. Below, to about 80 ft, the rock is grain supported, less well sorted, unbedded, and contains no coating. The rock is vuggy, with drusy calcite lining vugs at certain intervals. Similar transitions from bedded oolite to vuggy lagoonal facies have been cited at roughly this depth from other islands. Allochems are intraclasts and skeletal material, mostly mollusks, miliolid and peneroplid foraminifers, red algae, and Halimeda plates. Burrowing is evident below 55 ft. The rocks are sparites, but some mud matrix is present sporadically. Fr m 80 to 110 ft, the rock is micrite or pelmicrite, the few scattered fossils are foraminifers and red algae. Pelmicrites predominate through the rest of the core; below 110 ft extensive dolomitization has occurred.

Cementation, leaching of cryptocrystalline grains and infill by drusy calcite, neomorphism of cryptocrystalline grains to microspar, loss of aragonite, and concurrent loss of Sr increase with depth. Stable isotope analyses show ^dgr O¹⁸ and ^dgr C¹³ becoming progressively more negative with depth. Fe concentration shows a peak at 90 ft and is probably indicative of major pedogenesis.

Thin sections show some of the difficulties associated with attempting to differentiate pore-precipitated calcite spar from neomorphic spar in grain-supported rocks which contain some mud matrix. This difficulty is heightened by the "micritization" of allochems, diffusing into the spar cement.

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