Results and conclusions

Analysis of the super-gather shown in Figure , suggests the higher effective fold at near offsets (compared to 2-D experiments) leads to improved vertical resolution in the very near surface. Hyperbolic reflection events are clearly visible above the water-table reflector. Additionally, the frequency content of the data is sufficiently high to see that what appeared to be the water-table reflector at lower frequencies is in fact two distinct events of positive polarity separated by about 4 ms ($\approx$ 50 cm).

Unfortunately, the low signal-to-noise ratio makes it difficult to resolve 3-D structure on the water-table or the weaker reflectors both above and below it. Figure  shows the stacked 3-D data, stacked again in the X and Y directions. There does indeed appear to be a small amount of structure in the X direction (perpendicular to the shoreline). This is also apparent on the timeslice shown in Figure . It is unlikely to be an artifact of the acquisition geometry or processing, since the feature is not symmetric in the X=Y plane.