Alyssa Philipson '98

    High resolution (2-10 kHz) Edge Tech Geo-Star sub-bottom profiles were collected along 45km of "sedimentary structure-rich" track lines around the island of San Francesco in the lagoon of Venice, Italy. This survey was performed and mapped out to asses the extent of channel migration in the area. Sedimentary structures along each track line are illustrated to reveal several regions of distinct structures. The layout of sediment below the surface of the lagoon indicates a pre-lagoonal transgressive surface at depths between 5.8m and 6m. The dipping beds, interpreted as channel fill, were measured for depth and apparent angle of dip and covered much of the survey area. Two lines intersect with dipping beds at seven points where the true dip of the beds was calculated to be 3-11 degrees down toward the adjacent channel bank. Comparison of the angle and direction of the dip, reveals similarities to the modern channels and were thus concluded to be the bank fill/channel point bar deposits of channel meander migration. The horizontal reflectors of subtidal mudflats are present above and below these dipping channel bank deposits. Trapped gas acting as a strong reflector obscures acoustical penetration as do areas of thick (greater than 1m) sand deposits. Interpretation and analysis of these data support the theory of extensive channel migration within the lagoon and aid in future geo-archeological and environmental works at this location as well as other settings analogous to this study.