Significance Some of the most pivotal questions in human history necessitate the investigation of archaeological sites that are now under water. These contexts have unique potentials for preserving ancient sites without disturbance from later human occupation. The Alpena-Amberley Ridge beneath modern Lake Huron in the Great Lakes offers unique evidence of prehistoric caribou hunters for a time period that is very poorly known on land. The newly discovered Drop 45 Drive Lane and associated artifacts presented here provide unprecedented insight into the social and seasonal organization of early peoples in the Great Lakes region, while the interdisciplinary research program provides a model for the archaeological investigation of submerged prehistoric landscapes.

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Exploration for submerged prehistoric archaeological sites in the Great Lakes (North America) is a major challenge due to difficulties in locating scant cultural artifacts in lake-bottom sediments. Stone tool microfragments (microdebitage, <1 mm) can be abundant (>10 6 per tool) and more dispersed around tool-making sites, but have not been identifi ed previously in an underwater context. To evaluate their use as a submerged site indicator, microdebitage analysis was conducted on fi ve lake sediment cores from a shallow lagoon adjacent to a long-occupied prehistoric site (McIntyre site, Rice Lake, Ontario). We identifi ed 155 microdebitage fragments within a distinctive muddy peat horizon (2-2.5 m depth) using light microscopy and scanning electron microscopy methods. The microdebitage consisted of angular to very angular quartz fragments (400-1000 µm) with characteristic conchoidal fractures and fl ake scars produced by mechanical percussion. The microdebitage horizon had a distinctive bimodal particle size peak and contained a low-diversity soil thecamoebian assemblage (Phryaginella, Bullinularia sp.) indicative of a wetland environment that formed during an early Holocene shoreline transgression. Accelerator mass spectrometry 14 C dating of wood fragments yielded ages of 9470-8760 ± 50 yr B.P. (11,070-9560 cal [calibrated] yr B.P.), indicating a Late Paleoindian-Early Archaic age for the deposit. Results demonstrate that coring and microdebitage analysis are effective tools in the search for underwater prehistoric sites and can be employed more broadly in exploration of submerged landscapes in the Great Lakes basins.

Colonel By Lake, located near Kingston, Ontario, was created in the early 19th century during the construction of the Rideau Canal waterway. Canal flooding inundated a large area of the Cataraqui River lowlands, submerging important pre-contact and colonial settlements. In order to gain a better understanding of the pre-canal environment and its archaeological setting, a systematic bathymetry and side-scan sonar survey was conducted over a 2-km 2 area of Colonel By Lake. A 2-D digital bathymetric model (DBM) of the lake bottom was constructed and overlain with side-scan mosaics to map the paleogeography of the river flood plain. The data-fused sonar images clearly identify the submerged pre-canal topography, including the former Cataraqui River channel, relict meanders, tree stump fields, and bedrock uplands defining the valley sides. By comparing the DBM with landscapes depicted in pre-canal period maps (ca. 1828), the locations of several potential archaeological targets were identified. The DBM provides a basis for mapping submerged cultural resources in the Rideau and for predicting the location of undiscovered archaeological sites. The results show that integration of single-beam bathymetric mapping with side-scan imagery is an effective strategy for mapping submerged terrestrial landscapes and archaeological inventory in shallow water settings.

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