A combination of ground truth, provided by a single exploration well, and geometries apparent on seismic lines, provides new insight on the geologic development of the Maldives. The single exploration well documents the occurrence of more than 2000 m of Tertiary carbonate rock overlying volcanic basement. Seismic lines demonstrate that the shallow water Paleogene part of the drilled section is generally horizontally bedded, whereas the overlying upper Oligocene-Miocene carbonates have a distinctly prograding pattern. Significantly, the prograding pattern is directed inward from the edges of the present platform rather than outward into the thousands of meters of Indian Ocean water depths. The punctuated lateral expansion of the carbonate platforms is therefore bilaterally opposing, i.e., away from either of the Indian Ocean edges of the platform and toward each other. The same opposing directions of expansion are apparent in Saya de Malha bank, where, unlike the Maldives, coalescence has been completed in the form of a large carbonate bank. In both cases, the opposing directions of progradation appear to be the result of a structural change in depositional architecture of the kind usually associated with the thermal contraction development of sag basins.

Within this overall structural and stratigraphic framework, there is evidence that seismic stratigraphic relationships can vary considerably from atoll to atoll, indicating important local variations of the regional stratigraphy.

A second significant depositional change resulted from the onset of Pliocene-Pleistocene glacial fluctuations in sea level. The overall result was an emphasis on antecedent relief in controlling the distribution of carbonate facies, as evidenced, among other things, by the correlation of atoll lagoon depth and annual rainfall precipitation and the similarity between carbonate shoal patterns and karst topography patterns. Atoll morphology in the Maldives can be demonstrated to be very young in inception and would appear to represent arrested stages of lagoon infilling caused by Pleistocene lowstands of sea level.

The contrast between the lateral accretionary sedimentation of the Miocene and the vertical accretionary sedimentation of the Pliocene-Pleistocene can be reconciled by assuming that vertical accretion is the first response of carbonate deposition to a rising sea level, and lateral accretion is the response to a relatively stable sea level. Thus the dominance of vertical accretion in the Pliocene-Pleistocene reflects the frequent sea level changes that aborted the lateral accretion filling processes. The end product of shallow water carbonate deposition is not the current anthropocentric view of Holocene morphology as an end stage, but rather the more creditable view that it marks a transitional stage leading to the progradation development of the flat-topped carbonate banks commonly s en in the geologic record.