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 lake, swamp, coastal shoreline, tidal flat, or estuary ecosystems. The den typically has many tunnel openings, one of which generally allows the otter to enter and exit the body of water. Female North American river otters give birth in these underground burrows, producing litters of one to six young. North American river otters, like most predators, prey upon the most readily accessible species. Fish is a favored food among the otters, but they also consume various amphibians (such as salamanders and frogs), freshwater clams, mussels, snails, small turtles and crayfish. The most common fish consumed are perch, suckers, and catfish.