The use of acoustic imaging to reveal fossil fluvial systems-a case study from the southwestern Sea of Galilee

The analysis of reflected, high-resolution seismic data shows a distinct separation of regions with good and poor seismic penetration. Additional analysis of core data revealed good correlation between grain size and seismic penetration. As a case study, a shallow geophysical survey using a Chirp profiler was conducted in the southwestern part of the Sea of Galilee. By correlating the seismic and core data we found that areas with good seismic penetration represent coarse clastics, while poor seismic penetration is related to fine clays. New detailed bathymetric mapping and bottom morphology images combined with the penetration characteristics of the Chirp signal reveal a large alluvial fan consisting mainly of coarse material (sand to pebbles). A fine-grained band of mostly clay-size material, associated with an asymmetric bathymetric channel, continues the trend of the old entrance of the Yavniel Creek into the Sea of Galilee. We interpret the fine-clay stripe to be a low energy streambed of the Yavniel Creek. The clear relations between the reflected Chirp signal and the grain size of the water-bottom sediments suggests that this type of survey can be used to characterize depositional environments.