The oil fields of New York represent the extreme northeastern extension of the Appalachian oil fields. The most westerly New York pool is located in Cattaraugus County and is in reality the northerly continuation of the Bradford pool of Pennsylvania. At the east, and confined to Allegany County, is the Richburg pool, the largest and most productive in the state. Several smaller pools occur--among them the Marsh pool in Steuben County, which, with the exception of the Gaines oil pool in Pennsylvania, is the most easterly producing pool in the United States.

The productive sands of New York are all of Devonian age. The oil region is a dissected plateau, and depth of wells in the main sands ranges from about 900 feet in the valleys to more than 2,000 feet in the uplands. There is a slight regional southwest dip, and a few low anticlines and synclines have been recognized. Several types of sand are found, though on the whole the sands are fairly persistent. The presence of oil in synclines and the absence of salt water from most parts of the fields are noteworthy features.

The total production of oil since the development of the fields nearly fifty years ago is 75,000,000 barrels. The wells are small and yield oil slowly; one well that was drilled in 1879 is still being pumped.

During the last twenty-five years there has been no important lateral extension of the pools, nor have deeper producing sands been discovered. The present annual production is more than double that of ten years ago. Increase in production during recent years is due largely to flooding methods by which hydrostatic pressure on the oil sand is maintained through the use of water wells.