798 KENTUCKY by gentle undulations. The southeast is broken by the Cumberland mountains and their off- shoots. Narrow, deep, and gloomy valleys in- tervene between the ridges. None of the sum- mits attain a greater altitude than 3,000 ft., and their mean elevation does -not exceed 2,000 ft. The whole of this region is well wooded, especially the foot hills and valleys. N. and W. of the hilly region lies what may be called an upland, which extends from the Big Sandy river to Ion. 86 W., and comprehends more than half the whole area of the state. Its sur- face is gently undulating, but it is intersected by numerous narrow and deep valleys in which the rivers run. Though this upland is sparing- ly provided with spring water, its soil is of the first quality and equal to any in the Union. It is included in the tract of blue limestone which extends from the Ohio river, between a point about 40 m. above Louisville and the eastern limits of Mason co., about 10 m. above Maysville, southwardly to the Cumberland riv- er, and is known as the " blue grass region." The W. portion of the state is divided between the " barrens " and a country which is partial- ly hilly. The barrens, which occupy chiefly the tract between the Green and Cumberland rivers, in their natural state are generally des- titute of trees, resembling in this respect the prairies N. of the Ohio river ; but the level sur- face is diversified by low round-topped hills, called " oak knobs " on account of the trees which cover them. This tract was formerly considered the least fertile portion of the state, but the value of its red calcareous soils has greatly increased. The alluvial bottoms be- tween these hills and the Ohio and its afflu- ents are exceedingly rich. On the north and west the barrens are margined by a more broken and hilly country, which gradually pass- es to the low flats which skirt the Ohio and Mississippi rivers. This tract is superior in fertility to the barrens, but cannot be compared with the upland country. Kentucky is amply provided with noble streams. The Mississippi forms its W. limit for 80 m. Along the N. W. and N. boundary runs the Ohio in a winding course for nearly 600 m., navigable through- out, and affording with its chief affluents water communication to all parts of the state. The Mississippi receives from Kentucky only a few inconsiderable tributaries. Of the streams which flow into the Ohio, the most eastern is the Big Sandy, which has its sources in Vir- ginia and West Virginia ; where it approaches Kentucky it turns nearly due N., and continues in that direction to its outlet, forming the boundary between Kentucky and West Vir- ginia ; it is navigable only for a short distance, owing to falls which occur where it issues from the mountain region. The Licking rises in Floyd co., flows with many windings in a N. W. direction for more than 200 m., and falls into the Ohio between Covington and Newport, opposite Cincinnati; in winter and spring it is navigable for about 70 m. The dif- ferent branches of the Kentucky river rise in the Cumberland mountains, and form by their union a considerable stream, which flows first N. W., then S. W., and at last N. N. W. ; its course is about 260 in., and though very rapid it may be navigated by steamboats 80 m. to a point 20 m. above Frankfort, and by small boats for 100 m. higher. Green river rises in the W. districts of the upland region, and flows W. for a great part of its course, to its junction with its chief affluent, the Big Bar- ren, where it turns N. W. and finally N., join- ing the Ohio about 50 m. above the Cumber- land ; its length is about 300 m., and it is navi- gable for steamboats to Greensburg, 200 m., and for boats nearly to the heads of the stream. Navigation was obstructed by falls about 50 m. above its mouth, but a lock and dam at that point has obviated the difficulty. Cumber- land river rises in the valley between the Cum- berland and Laurel mountains; it traverses both the mountain and the upland regions, generally in a westerly direction, but on ap- proaching the barrens it turns S. and enters Tennessee, where it makes a large bend and then reenters Kentucky with a N. W. course, and so continues to the Ohio, which it enters about 10 m. above the mouth of the Tennes- see ; it is nearly 600 in. long, and as its current is comparatively gentle it offers an easy navi- gation for sloops and steamboats as far up as Nashville, Tenn., 200 m. from its mouth, and at high water to Burkosville, Ky. ; for boats of 15 tons it is navigable for 300 m., and for river boats much higher. The Tennessee flows only about 70 m. through Kentucky ; it admits steamboats to Florence, Ala., 300 m. from its mouth. Kentucky lies wholly in the great region of stratified rocks of the west. These traverse the state in layers so nearly hor- izontal, that often over broad districts no dip is perceptible to the eye. Through the central portion of the state, from N. to S., the Silurian groups, which are here almost exclusively calcareous, thus overspread the surface for nearly 100 m. in width, and form the great central axis of the lowest rocks. At Louisville they disappear by reason of their very gentle westward dip, and pass beneath the limestones of the Devonian age, which here lie exposed in horizontal strata, forming the bed of the river and the reefs which occa- sion the falls at this place. They are succeeded by the carboniferous limestone ; and still fur- ther W. the coal measures, commencing at Rome on the Ohio river, are traced almost to the mouth of this river. This is the southern end of the coal field of Illinois and Indiana, which extends S. nearly across the western portion of Kentucky. (See COAL.) In this portion occurs the Breckenridge coal, former- ly extensively used in the manufacture of kero- sene. To the east, about 100 m. from Louis- ville, the same repetition of the formations is encountered, as the Silurian rocks dip E. on this side of the axis; and the coal measures
