DISTRIBUTION. The productive horizons of nat ural gas cover the entire series of Paleozoic rocks, and reservoirs are found even in Tertiary strata. The main supply for the United States comes from the Appalachian field, and the Ohio Indiana field. The former extends from New York into Tennessee, and contains specially pro ductive districts in Pennsylvania and West Vir ginia. The gas is obtained from several sand stone beds within the Devonian, and is closely associated with oil, the two owing their accumu lation to the presence of a series of low anticlinal folds. The sandstone beds or 'sands' are sepa rated by varying vertical distances, and are known by different names. The Ohio-Indiana field is unique in that the gas which is associat ed with oil occurs in Trenton limestone, along a dome-shaped uplift of rock known as the Cin cinnati Arch, and especially where the rock has been rendered somewhat porous by dolomitiza tion. This anticline extends in a northeast-south
west direction from Indiana into Ohio. In addi tion gas has also been obtained in Ohio from the Sub-Carboniferous. Both of these areas in Ohio are now nearly exhausted, and the supply obtained within the State comes from new and small fields. In southeastern Kansas gas is ob tained from the Carboniferous shales, the area which is known as the Iola gas-field having come into prominence during the last few years. Its product is important because of the fact that the field lies not far from the Ozark zinc region, and the gas is employed for smelting the ores. The gas is found at depths ranging from 500 to 1000 feet. Some natural gas is also ob tained from Kentucky, Illinois, Texas, South Dakota, Colorado, California, Missouri, and Texas, but the amount produced in most cases is small.