The present geometry and sand-transport regime on the oolite shoal appear to result from interplay between storm-generated and tidal currents. A portion of this sand-wave field continues to migrate slowly into the shelf lagoon in response to the dominant bankward energy flux and maintains itself in pace with the slowed sea-level rise.

The adjacent sand-wave field developed rapidly during the deceleration in sea-level rise which occurred around 3,500 yr BP. The linear sand ridges, which require a higher flow velocity for development and maintenance, became less active and eventually were stabilized by marine grasses. As sea level continued to rise, bankward flow velocities decreased as the reentrant channeling effect decreased. These now-relict bedforms developed approximately 4,000 yr BP. Subsequent to the initial sea-level rise over the bank approximately 5,700 yr BP, these reentrants funnelled bankward-directed flow which resulted in two zones of bedforms: (1) an outer zone of linear, parallel-to-flow sand ridges (200-500-m spacing, 3-4 km long, 2-3 m in height) oriented in a radiating pattern away from the reentrant throats (2) an inner belt of sand waves oriented transverse to flow (90-300-m spacing, 1-2 m in height). It has developed immediately bankward of two large, intrareef bank-margin reentrants which allow a relatively unrestricted flow of tidal and storm-generated currents on and off the bank top. Lily Bank is oriented parallel to the bank margin and is independent of underlying bedrock topography.

Study of the response of an active oolite sand shoal (Lily Bank), located along the northeastern margin of Little Bahama Bank, to its physical environment and the Holocene sea-level rise has provided a developmental sequence from initial formation to present maintenance for this marine sand belt.

Bahamas oolite