Trout Island Shoals and High Island Reef

Figure 5.1 - Shaded relief map of Trout Island Shoal (upper left), Trout Island area, and west coast of High Island. The rough nearshore relief west of High Island (bedding in the Devonian Bois Blanc Formation?) transitions abruptly offshore to a smooth depositional substrate (sand?). North of High Island the east-west linear trends similar to those seen on Boulder Reef underlie sediment drapes (sand?). The linear and box work texture is similar to that seen in Boulder and Gull Island reefs. The morphology of Trout Island Shoal suggests a large sand shoal migrating eastward over underlying units of the Devonian Bois Blanc Formation (Fig.1) or glacial deposits. Two or three gouges or grooves of unknown origin (ice?, man made?) extend east from the south end of the shoal for over 1 km. The slopes of the Shoal are relatively steep, especially on the the eastern edge.