The Utica Shale is an Upper Ordovician, organic-rich shale formation that underlies much of the northeastern United States and nearby Canada. Named for Utica, New York, where Ebenezer Emmons first described it in 1842, it varies greatly in thickness and depth across the Appalachian Basin and has become a major focus of oil and gas exploration. Drilling expanded in Quebec, Ohio, and New York during the early twenty-first century, though moratoriums on hydraulic fracturing shaped development in Quebec and New York. Large estimates of recoverable gas, oil, and natural gas liquids drew intense attention, while the formation also affected Montreal Metro construction and figured in climate and energy policy debates.