A continuous marine seismic-reflection survey system was used to define the configuration of shallow sedimentary layers underlying the Charlotte Harbor and Venice areas, southwest Florida. Seismic profiling was conducted over a distance of about 57 miles of Charlotte Harbor, the Peace and Myakka Rivers, and the Intracoastal Waterway near Venice using a high resolution energy source capable of penetrating 200 feet of sediments with a resolution of 1 to 3 feet. Five stratigraphic units defined from the seismic records includes sediments to Holocene to early Miocene age. All seismic-profile records are presented, along with geologic sections constructed from the records. Seismic reflection amplitude, frequency, continuity, configuration, external form, and areal association were utilized to interpret facies and depositional environments of the stratigraphic units. The despositional framework of the units ranges from shallow shelf to prograded slope. The stratigraphic units are correlated with the surficial aquifer and intermediate artesian aquifers, and permeable zones of the aquifers are related to the seismic records. (USGS)