Figure 28. Interpretation of the sea floor in the National Oceanic and Atmospheric Administration survey H12298 study area. Features include bedrock, boulders, cobbles, drumlins, glaciolacustrine sediment, trawl marks, and sand waves and megaripples. Areas of the study area that are not outlined appear generally featureless in the multibeam bathymetry data and are interpreted to be modern marine sediments. Interpretations are based on multibeam-bathymetry, sidescan-sonar, sediment, and photographic data collected in the study area.