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 of the 1812-era fort with a massive new Third System masonry fortification, known as Fort Montgomery. Portions of this fort are still standing. In the early 19th century, the construction of the Champlain Canal connected Lake Champlain to the Hudson River system, allowing north-south commerce by water from New York City to Montreal and Atlantic Canada. In 1909, 65,000 people celebrated the 300th anniversary of the French discovery of the lake. Attending dignitaries included President William Howard Taft, along with representatives from France, Canada, and the United Kingdom. In 1929, then-New York Governor Franklin Roosevelt and Vermont Governor John Weeks