This district was at one time the bed of a vast lake of the Lower Silurian period; on its floor were laid several sedi mentary deposits: Upper Silurian, Devonian, Subcarboniferous some 5,000 feet deep, and on these Carboniferous, (coal measures) to 3,000 feet more. The great Appalachian uplift raised this some 5,000 feet, the surface forming a dome in the centre; then forces of denuda tion acted planewise across the top, cutting away all the upper strata down to the original Lower Silurian in the middle—whence the outcrop of blue limestone in the Blue Grass region — and other strata to varying degrees in other parts, leaving the coal measures exposed in two great patches 100 miles apart at the edges. In the southwest the Subcarboniferous limestone is at the top— the region of caves and sinks.
Mineral Bituminous coal mining has grown rapidly in recent years, the output rising in 1917 to 27,E09,976 tons, and giving Kentucky fifth place in the Union. While the Western field yielded the larger proportion in 1907, the Eastern field produced two-thirds of the total in 1917. Rich veins from six to eight feet thick occur at shallow depths permitting easy exploitation at minimum expense. This condition has invited capital from other States. Practically all the increased railroad mileage along the Louisville and Nashville and Chesa peake and Ohio lines is in the coal districts. Company towns, such as Jenkins and Mc Roberts, grew up quickly to serve the mining communities. The chief markets are the lake ports, though the rich content of some of these coals for coking and by-products has created special demand in Saint Louis and Pittsburgh. Cannel, or gas coal, is plentiful in Morgan County, yielding 43,000 tons a year. Petroleum and gas wells, slightly utilized by the early settlers, and almost undeveloped even a decade ago, sprang into prominence with the outbreak of the World War. Traces of oil and gas occur in more than 50 counties. While gas production is vastly exceeded by the West Vir ginia fields, the smaller Kentucky field is now tapped by lines which supply Mount Sterling, Winchester, Lexington and other cities of the Blue Grass, and Louisville. Gas production in 1910 attained a value of $891,000. The oil in dustry, however, has caused much more excite ment. The older fields in Wayne County on the Tennessee border, extending northeast through Wolfe County, and served by pipe lines for many years. seemed to be stationary in pro duction; but the high prices created by war demands led to tests in adjoining counties, with most surprising results. At depths rarely ex
ceeding 1,300 feet in Estill and Lee counties in the eastern section, and about Allen County on the Tennessee border, new supplies appeared.
The old marketing facilities proved utterly inadequate. A pipe line which in 1914 marketed only 480,000 barrels received in 1918 over 4,000,000 barrels, an increase of 800 per cent in four years. The total yield of the two fields, east and west, now exceeds 8,000,000 barrels annually. The oil is of the best grade, com manding a high price. Iron, which gave good promises of expansion about the year 1880, has faded away before the advance of the north western ores, which are used in the mills at Ashland. Kentucky iron is profitably mined only near Cumberland Gap, and in Trigg, Lyon and Caldwell counties in the west. Of minor minerals one may mention the limestone prod ucts, such as Kentucky River marble, asphalt, sandstones. clays, barytes and phosphates used for fertilizers. Extensive mining of fluor spar occurs in Crittenden and Livingston counties adjoining the Illinois field. Mineral springs are numerous, but only 12 were ranked as com mercial in 1915.
Climate and Mississippi bottoms are malarious, but the rest of the State is free from objectionable tendencies. The death rate normally 152 per thousand in creased to 17 per thousand during the influenza epidemic in 1918. Mean winter tempeature is 35° F., while the annual average is 55° F. Owing to its exposure to storms from south west and northwest alike, considerable varia tion may occur, tempered, however, by the proximity of the mountains to the east. Water is abundant in all parts of the State. The average precipitation is 44 inches without a record of excessive drouth in any year.
About a third of the State is cov ered with commercial forests. Along the Alleghany slopes there is a great quantity of fine timber, most of it being hardwood of astonishing variety. Oaks of many different kinds — white, red, black, post, overcup, chest nut and black-jack—hickory, black walnut, blue ash, maple, elm, beech, chestnut, poplar, sweet gum, yellow pine, sycamore and hack berry are only a portion of its wealth, still largely virgin, though now being rapidly ex ploited. Poplar, black walnut and cherry are now scarce. Some cypress occurs about Reel foot Lake.