Two transverse morphological tracks across the front of the Mediterranean Ridge were swath mapped with a Hydrosweep instrument system. Along the tracks, ridges and troughs at the front of the accretionary prism are disrupted and bent in the direction of relative plate convergence. The longer of the two tracks extends to Bannock Basin, a brine-filled depression with a closed outer moat around a central mound. Seismic reflection data and a gravity anomaly show a buried circular seamount beneath Bannock Basin whose summit is the mound. This indicates an origin of the larger transverse track and Bannock Basin from a subducting seamount. Beneath Bannock Basin, the seamount has displaced about 340 km3 of the Messinian section and yet the seafloor has not been uplifted. Therefore, considerable evaporitic material is inferred to have been displaced by the seamount and Bannock Basin is a likely vent for large quantities of dissolved materials from the disrupted Messinian evaporitic sequence.