GEOPHYSICAL IMAGING OF A DROWNED LANDSCAPE, COLONEL BY LAKE, ONTARIO, CANADA

Colonel By Lake, located at Kingston Mills, Ontario, was created in the early nineteenth century, when the builders of the Rideau Canal flooded the Cataraqui River. The flooding inundated a large area that is known to include colonial and aboriginal sites of archaeological importance. In order to gain a better understanding of the submerged pre-canal landscape and its archaeologic setting, a systematic geophysical survey was conducted on the Colonel By Lake. The lake bed was imaged using side-scan and single-beam sonar and the infill stratigraphy investigated with sub-bottom seismic profiling and coring. A digital elevation model (DEM) was created for the drowned flood plain and overlaid with a side-scan mosaic to identify the former river course and landscape features of potential archaeological importance. The DEM clearly shows the pre-canal landscape, including a large meandering river channel, flood plain and bedrock upland areas that form interfluves. The side-scan data also identify numerous tree stumps, which define the limit of pre-canal forest cover. Comparison of the DEM with archaeologic finds onshore suggests that a large bedrock promontory (Esther Head) on the south side of the lake was an aboriginal encampment overlooking the former Cataraqui River. The study shows that the lake bed DEM, when integrated with core and seismic data, provides important insights into the pre-canal paleoenvironments and provides a useful tool that can be used to guide further archaeological work.