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
Ten Thousand Islands Ten Thousand Islands The Ten Thousand Islands are a chain of islands and mangrove islets off the coast of southwest Florida, between Cape Romano (at the southern end of Marco Island) and the mouth of Lostman's River. Some of the islands are high spots on a submergent coastline. Others were produced by mangroves growing on oyster bars. Despite the name, the islets in the chain only number in the hundreds. The northern part of the Ten Thousand Islands, between Cape Romano and Everglades City, is in the Ten Thousand Islands National Wildlife Refuge. The southern part of the Ten Thousands