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 North American river otters of different groups portray mutual avoidance. Home ranges of males are larger than those of females, and both sexes exhibit intra- and intersexual overlap of their domains. Communication among North American river otters is accomplished mainly by olfactory and auditory signals. Scent marking is imperative for intergroup communication. The North American river otter scent-marks with feces, urine, and possibly anal sac secretions. Musk from the scent glands may also be secreted when otters are frightened or angry. North American river otters can produce a snarling growl or hissing bark when bothered, and a shrill whistle when