Uninterpreted seismic profile reveals a variety of morphology associated with the sediment cover in this area. Large and relatively thick sand ridges offshore contrast with sand flats and localized sandwave fields related to the Tampa Bay ebb-tidal delta nearshore. Overall, the base of the Holocene is extrapolated from vibracore data that supports the seismic interpretations. Additional evidence includes hardbottoms (pre-Holocene bedrock) and probe-rod measurements of sediment thickness. Typically, there is poor acoustic contrast between the Holocene sediment cover and the Pleistocene exposure surface, which is attributed to the karstic and weathered nature of the underlying pre-Quaternary bedrock.