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
Fort Montgomery (Lake Champlain) Fort Montgomery (Lake Champlain) Fort Montgomery on Lake Champlain is the second of two American forts built at the northernmost point of the American part of the lake: a first, unnamed fort built on the same site in 1816 and Fort Montgomery built in 1844. The current massive stone fortification, the second fort, was built between 1844 and 1871 at the Canada–US border of Lake Champlain at Island Point in the village of Rouses Point, New York. Construction was begun on the first fort at this location, an octagonal structure with walls, in 1816 to protect against an attack from