During the review of the Carruthers Watershed, it came to the attention of TRCA hydrogeology staff that the Iroquois Shoreline in the Geologic Folder of the TRCA corporate data layers did not follow the Physiography established by Chapman and Putnam 1984 (The Physiography of Southern Ontario). It was then noted that within the Duffins Watershed the shoreline did not extend north along the Duffins River nor turn south along the height of land at the hamlet of Greenwood - instead the shoreline appeared to offset by about 1 km. TRCA hydrogeology staff brought the issue forward with Dr. Rick Gerber of the YPDT-CAMC team who stated that he had noticed the same thing when he prepared the Duffins and Carruthers watershed report in the early 2000s. He believed the error to be a NAD 83 / 27 conversion error.