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
New York State Route 373 America. The park was further protected in 1894 when a clause was added to the New York State constitution which banned the selling of timber from state parks. On April 16, 1827, a team of three surveyors were commissioned to determine a routing for a new highway leading from Hopkinton, a town in northeastern St. Lawrence County, to Lake Champlain. The task took 26 days, after which it was determined that the highway would meet Lake Champlain at Fort Kent. An act authorizing the construction of the highway was passed by the New York State Legislature on April 18, 1829.