Thousand Islands – Frontenac Arch is one of four ecoregions of the Mixedwood Plains. The Thousand Islands in the Saint Lawrence River have a distinctive flora and fauna and are a part of the biological corridor. The bedrock is mostly gneiss, granite and marble, more than a billion years old. The Frontenac terrain is the youngest of the Ontario portions of the arch, dated at 1.2 billion years old. These rocks were once part of a large mountain chain of the ancient supercontinent of Rodinia. There is also a meteor crater near Holleford, where the shield meets the limestone plains of southeastern Ontario. The area
North American river otter by North American river otters in various areas. Susceptibility of these species is greatest during the summer (when waterfowl broods are vulnerable) and autumn. The North American river otters have also been known to catch and consume moulting American wigeon ("Mareca americana") and green-winged teal ("Anas crecca"). Other species of birds found within their diets include: northern pintail ("Anas acuta"); mallard ("Anas platyrhynchos"); canvasback ("Aythya valisineria"); ruddy duck ("Oxyura jamaicensis"); and the American coot ("Fulica americana"). Although they consume birds, North American river otters do not feed on bird eggs. Aquatic invertebrates have been recognized as an integral part of