Figure 7. Seismic-reflection profile across eastern end of study area from Needell and others (1983a) with interpretation and corresponding sidescan-sonar image. Paleozoic bedrock, Wisconsin glacial drift including till, moraine, and glaciolacustrine sediments, and Holocene marine and transitional deposits are shown. Stratified drift in the south may be glaciolacustrine sediment. Sidescan-sonar image shows areas of sand waves, benches, trawl marks, and high backscatter. Benches tend to coincide with a contact between glaciolacustrine sediment and till. Depths are based on an assumed compressional wave velocity of 1500 m/s. Vertical exaggeration: 13X. Location of profile shown in fig. 2.