Washington County, New York is part of the Great Appalachian Valley (also known simply as the 'Great Valley') which is a long narrow valley strip often between tall mountain ranges. The county transitions from the Taconic Mountains to the Adirondack Mountains, and from the Lake Champlain Valley to Hudson River Valley. Much of the county is part of the slate valley of the Upper Taconic Mountains (Taghkanic, meaning 'in the trees'). The eastern boundary of Washington County is the New York–Vermont border, part of which is Lake Champlain. This is also the border with New England proper. The northern end of the county is
Geography of New York (state) the north. Additionally, New York touches the Atlantic Ocean to the southeast, and two of the Great Lakes: Lake Erie to the west and Lake Ontario to the northwest. New York is part of the Marcellus Shale, a gas-rich rock formation which also extends across Ohio, Pennsylvania and West Virginia. New York lies upon the portion of the Appalachian Mountains where the mountains generally assume the character of hills and finally sink to a level of the lowlands that surround the great depression filled by Lake Ontario and the St. Lawrence River. Three distinct mountain masses can be identified in