The seismic data from Upper Lake Louise is generally obscured by multiples in areas of bathymetric lows, as shown in the Distribution of Features map. This is consistent with lake bottoms of homogeneous sands, but also may be due to organic material accumulating in the deepest portions of the lake which tend to absorb the acoustic signal. The southern portion of the lake is characterized by a strong reflection at 20-24 ms (solid blue line, middle of C-C’). Depth to this mid-level horizon is shown in red numbers on the Distribution of Features map, and indicates a slight dip to the south across the lake. Correlation with gamma logs from wells adjacent to the lake would suggest that the horizon represents stratigraphy within the Hawthorn Group. The horizon is overlain by material of low reflective potential, possibly fill material or massive clays (middle of C-C’). Sediments within the Hawthorn Group exhibit major slumping and discontinuities, as seen in the example profiles. Profiles A-A’ and B-B’ show possible sinks, along with accommodation fractures or faults adjacent to the subsidence. The northern portion of the lake is characterized by numerous type 4 features (A-A’, B-B’, C-C’), or a common characteristic where dip in a reflection is apparent but obscured by noise (C-C’). The features extend from near the lake bottom to depth and may indicate areas of potential leakage. A horizon very near the sediment surface can be resolved from the data (solid blue line), with infilling (red lines). At depth, a strong reflective horizon is evident between 30-48 ms (dashed green line). The horizon is punctuated by numerous discontinuities and elevation changes. The gamma logs indicate the top of the Ocala Limestone to be at about -15 to -24 m (-50 to -80 ft) below mean sea level, which correlates with this horizon. Dissolution of the Ocala Limestone would cause the subsidence seen in the overlying material of the Hawthorn Group. If the material above the mid-level horizon is impermeable massive clays, the discontinuities represent major breaches across the confining unit. Evidence of the breaches are substantiated by reports from local residents who indicate that a spring once flowed from the northwest section of the lake decades ago (Track Map). The spring was used as a water supply until flow ceased as the majority of the region changed from an area of discharge to recharge to the Floridan aquifer (Boniol and others, 1993).