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
Thousand Islands Border Crossing Thousand Islands Border Crossing The Thousand Islands Border Crossing connects the towns of Alexandria Bay, New York and Ivy Lea, Ontario on the Canada–US border. The crossing is via the international span of the Thousand Islands Bridge. The Thousand Islands bridge, which was completed in 1938, is actually a system of three bridges and the island roadways connecting them. The international span, which crosses a small rift between Wellesley Island in the US and Hill Island in Canada, is only in length. A second, parallel span was built in 1959 to accommodate congestion at the ports of entry. The US