Champlain Valley southward into the Valley of Vermont. The Vermont Lowlands are primarily underlain by sedimentary rocks, especially limestone and shale, though metamorphic rocks such as marble and slate are also present. Lake Champlain is situated in the Champlain Valley between the Green Mountains of Vermont and the Adirondack Mountains of New York, drained northward by the Richelieu River into the St. Lawrence River at Sorel-Tracy, Quebec (northeast of Montreal). Major tributaries of Lake Champlain include Otter Creek and the Winooski, Missisquoi, and Lamoille rivers in Vermont, and the Ausable, Chazy, Boquet, and Saranac rivers in New York. Lake Champlain also receives
Lake Champlain as late as the 1960s, but rejected for various reasons. The lake is also part of the 740-mile Northern Forest Canoe Trail, which begins in Old Forge, New York, and ends in Fort Kent, Maine. Burlington, Vermont (pop. 42,217, 2010 Census) is the largest city on the lake. The 2nd and 3rd most populated cities/towns are Plattsburgh, New York, and South Burlington, Vermont, respectively. The fourth-largest community is the town of Colchester. Lake Champlain contains roughly 80 islands, three of which comprise four entire Vermont towns (most of Grand Isle County). The largest islands: All active navigational aids on the