Figure 8. Seismic-reflection profile across western end of study area from Needell and others (1983a) with interpretation and corresponding sidescan-sonar image. Interpretation includes: Paleozoic bedrock, possible Cretaceous coastal plain sediments, Wisconsin glacial till and glaciolacustrine sediments, and Holocene marine and transitional deposits. Sidescan-sonar image shows sand waves in the north and benches, high backscatter, and trawl marks in the south. Benches occur at the contact between fluvial and glaciolacustrine sediments and within the glaciolacustrine sediment near the exposure of till. Depths are based on an assumed compressional wave velocity of 1500 m/s. Vertical exaggeration: 13X. Location of profile shown in fig. 2.