A new Champlain Sea fossil locality near Kars, Ontario has yielded at least 41 species of benthonic Foraminifera, 18 of which are recorded from this sea for the first time. Taxonomically the assemblage is almost identical to living faunas from Arctic seas. Paleosalinities of about 30 to 35 ppt and a range of annual paleotemperatures from 0 °C to 12 °C are indicated by the Foraminifera. A 14C radiocarbon date of 10 900 ± 100 a BP (GSC 2312) was obtained from shells of Hiatella arctica, suggesting deposition relatively late in the marine episode. The existence of arctic-subarctic environmental conditions at this time in Ontario can be directly attributed to the proximity of the post-Valders Laurentide ice sheet.