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 larger fish on land to eat, whereas smaller fish are consumed in the water. North American river otters may prefer to feed on crustaceans, especially crayfish ("Cambarus", "Pacifasticus", and others) more than fish where they are locally and seasonally plentiful. In Georgia, crayfish accounted for two-thirds of the prey in the summer diet, and their remnants were present in 98% of the summer spraint. In the winter, crayfish made up one-third of the North American river otter's diet. A study conducted on North American river otters in a southwestern Arkansas swamp identified a correlation between crayfish consumption, fish consumption, and