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 spp.), daces ("Rhinichthys" spp.), shiners ("Notropis" and "Richardsonius" spp.), and squawfishes ("Ptychocheilus" spp.); and Ictaluridae, which consists of bullheads and catfish ("Ictalurus" spp.). Other fish an integral part of the North American river otters' diets are those that are often plentiful and found in large schools: sunfish ("Lepomis" spp.); darters ("Etheostoma" spp.); and perches ("Perca" spp.). Bottom-dwelling species, which have the tendency to remain immobile until a predator is very close, are susceptible to North American river otters. These include mudminnows ("Umbra limi") and sculpins ("Cottus" spp.). Game fish, such as trout (Salmonidae) and pike (Esocidae), are not a significant