MINERAL RESOURCES AND :MINING. Both the upper and lower coal measures contain several workable seams interbedded between strata of shale, limestone, sandstone, and clay, and rang ing in thickness from two to over a dozen feet. It has been estimated that Ohio contains enough coal to supply the demand of the State for soft coal for 1000 years at the present rate of con sumption. The interbedding strata of the coal measures yield fire-clay and building stone, and here also are found the iron ores of the car bonate variety. The Salina group of the Silurian strata near Sandusky contains valuable gypsum deposits, and salt deposits also occur at various places. One of the most remarkable events in the mineralogical development of Ohio was the discovery in 1884 of petroleum in the Trenton limestone formation of Lower Silurian age. This formation as well as tbe Upper Silurian inclosed also considerable reservoirs of natural gas.
Ohio's output of coal increased from about 6,000.000 tons in 1880 to 13.562,000 tons in 1892. It did not exceed this figure again until 1898. In that year and in the two following years the increase was very rapid. The output in 1900 aggregated 18,958.150 short tons, amounting to 7 per cent. of the total output for the country. It was valued at $19,292,246. Only a !..mall amount of the coal output is used in the produc tion of coke. The average number of employees engaged in the coal industry in that year was 27,628.
The petroleum development has been of recent date. Little had been produced prior to 1885, which year marks the beginning of the swift progress of the industry. The yield inercas(Al from 90.081 barrels in 1884 to 661.580 in 1885, 10,010,86S in 1888, and 23,941,169 in 1896. The last is the record year. The output for 1900 was 22,362,730 barrels, valued at $24,091,601. This much in excess of that of any other State. and was over one-fourth of the total output for the United States. The petroleum is obtained in two geetions of the State, the southeast and northwest. The former it known as the Eastern district, and the latter—the more important— as the Lima district. In a third region, known as the Mecea-Belden district, small quantities of lubricating oil are obtained. The utilization of the State's natural gas resources is also of recent development. There are two gas fields corresponding in a general way with those of petroleum. The extensive use of gas for fuel
began in the Eastern district in the early seven ties. The value of the gas burned in 1880 was estimated at over 85.000,000. The product was extravagantly consumed, and the supply soon became exhausted, so that in 1885 the value of the product was only about $100.000. The de velopment of the gas fields in the northwest part of the State began at Findlay about this time, and the value of the output rapidly in creased until 1889. when it exceeded that of any previous year. After 1889 the output de clined steadily until 189S, since when its value increased again. amounting in 1000 to 82,178.234. From 1890 to 1900 the State was exceeded in rank with respect to the output of natural gas by Pennsylvania and Indiana, and since 1899 by 1Vest Virginia.
Ohio ranks first in the annual value of clay products, contributing 17.3 per cent. (1900) of the total output for the country. Their value increased from 810.860,934 in 1890 to $18,504,628 in 1900. Of the latter amount, $8.573.323 repre sented the value of the pottery (see .11anajnc Iarcs r. and $9,731.305. the brick and tile. The State regularly ranks first in the figures for the sandstone product. From an annual value of over $3,000,000 in the earlier years of the decade 1890-1000, Ohio's product fell to about half that amount. but rose in 1900 to $2.233.596. including grindstones and whetstones. Of these it produces over four times as much as all the rest of the country. the value for 1900 being $349.636. The output of limestone for the same decade fluent at (4I in value around 81,500.000,approximately half the product being burned into lime. Con siderable quantities of cement are annually manu factured. Iron ore was mined at an early period, and was of great importance to the industrial de velopment of the State. Recently, however, iron mining has bepome of less importance, both rela tively and absolutely. From 344.484 tons in 1886 the output fell gradually to 61.016 tons in 1900, the entire product being of the carbonate variety of ore, and giving Ohio first rank in the production of carbonate ore. In 1900 sales of mineral water were reported from fifteen springs. In the same year the production of salt amounted to $696,326, giving the State fourth rank.