The Eastern Kentucky Mountains include that part of the state east of the westward-facing Pottsville Escarpment. It includes the Cumberland (Allegheny) Plateau and the Cumberland Mountains, a term recently employed for Pine and Cumberland mountains and the intervening Middlesboro Basin (Fenneman, 1938). The western margin from the Tennessee line to Rowan County is a west-facing cuesta. This is the Pottsville Escarpment. Throughout most of its extent this cuesta is capped by the resistant eastward dipping Rockcastle conglomerate with a summit level of about 1400 feet. The Corbin sandstone forms a minor cuesta to the east. South of Somerset the level rises and near the Tennessee line reaches 1800 feet. In this region heavy sandstones intervene between the Rockcastle and Corbin, and the entire Lee section forms the cuesta. Northward the Escarpment breaks down with the pinching of the Rockcastle conglomerate, and the regional boundary is replaced by the somewhat less conspicuous Waverly Escarpment, which in Ohio is the more prominent of the two.
|FIG. 1. Pottsville Escarpment
from 10 miles west of Irvine. The hilltop
level of the lowland in the foreground is that of the Lexington
|FIG. 2. Red River valley in
the vicinity of Stanton, Powell County. The
broad valley floor is developed in the Ohio and Waverly shales.
|FIG. 3. A small cultivated
area looking east from Sky Bridge, northeastern
Powell County in the rugged western margin of the Eastern Coal Field.
|FIG. 4. A small rock shelter
in the Rockcastle sandstone near Sky Bridge,
northeastern Powell County. The development of such a shelter on a
narrow divide is the first step in the forming of one type of natural bridge.
Cumberland Plateau.—The Cumberland (Allegheny) Plateau is a maturely dissected plateau of varying altitude and relief and with local variation in character which is the expression of variation in rock outcrop and character. It is a region of dendritic drainage with its complementary maze of irregularly winding narrow-crested ridges and deep narrow valleys. Flat land, either upland or lowland, is at a minimum, though locally in areas of shale outcrop considerable bottoms have been developed. Also massive sandstones have given rise to local upland flats.
The crest of the Waverly Escarpment in the vicinity of the Ohio River is at 1200 to 1300 feet from which the upland level drops off with the dip to the southeast to about 1,100 feet at the western edge of the area of Pottsville outcrop, and farther east along the Ohio and Big Sandy rivers to 900 feet. Near Irvine the crest of the Pottsville Escarpment is at about 1400 feet from which the hilltop level drops off down the dip to form a lowland area at about 1000+ feet around Beattyville; similarly, elsewhere (pl. XXXVII). These lowland areas east of the Pottsville and Waverly escarpments are regarded as eastward extensions of the Lexington (Harrisburg) peneplain.
South of Jackson County the Escarpment rises above the Pennyroyal instead of the Blue Grass and attains an altitude of about 1,800 feet in southern Kentucky. The Pennyroyal surface (stripped plain) slopes southward from 1,300 to 1,400 feet at Muldraugh’s Hill to about 1,000 feet in southern Kentucky, above which the Pottsville Escarpment stands ±700 feet higher.
To the southeast of this marginal cuesta there is general increase in hilltop level, and with it relief, to altitudes of 2000 feet and more, above which Pine Mountain and others to the east rise. Relief along the western border ranges from ±700 feet at the north to ±1000 feet near the Tennessee line. At Pikeville and Barbourville relief is 900 to 1000 feet and ±750 feet respectively.
Davis (1923) recognized and named two sections:
The Ridge Top (and Limestone Valley) Settlements comprise mainly the region of outcrop of the Rockcastle conglomerate, the region of the westward-facing Pottsville cuesta with its deeply dissected eastward sloping strip plain. Streams have trenched themselves in steep-sided and precipitous-walled valleys, capped with cliffs often several hundred feet high. It is a region of rock shelters and natural bridges, and toward the east rapids and waterfalls, as the conglomerate passes from hillside to valley bottom. In the western portion near the Escarpment divides are narrow but they involve considerable summit area eastward. Valleys in the western portion tend to be of fair width with considerable bottom land. Here streams have widened their valleys in the outcropping Ohio and Waverly shales. To the east as the Mississippian limestones and the Lee conglomerate come down to stream level, the bottom land disappears in narrow gorge-like valleys, to widen again eastward as these beds pass below drainage.
The ridge land is inferior with its thin sandstone soils and rapid erosion. In the broad stream bottoms of the western edge the extensive alluvial soils are productive.
The region of the Waverly cuesta in the northern counties is similar but less rugged.
The area of Creek Bottom Settlements comprises the rest of the coal field to the east. It is relatively low in its western part with altitudes of 1,100 and 1,200 feet, and near the Ohio River as low as 900 feet. From here, though, there is a regional increase in altitude, and with it relief and ruggedness of landscape southeastward to Pine Mountain. Dissection is more mature than in the region of Rockcastle outcrop. Ridges are almost without flat land except locally where stripped plains have been formed on some of the more resistant local cliff-forming sandstones.
The little flat land present is in the bottoms and along the larger streams, particularly in places where shale dominates. Farms are in the bottoms extending up every creek and branch and the steep hillsides are actively cultivated. In Magoffin County along the axis of the Paint Creek Uplift, earlier referred to as the Conglomerate uplift, the Rockcastle conglomerate locally recurs in outcrop. Valleys here have the aspect of those in the general region of Rockcastle outcrop.
|FIG. 1. Coal mine near
County (Caufield and Shook).
|FIG. 2. Harlan, Kentucky (Caufield
Shook). In this region of mature dissection
there is a minimum of flat lowland.
|FIG. 3. A Leslie County
(Caufield and Shook).
|FIG. 4. Levisa Fork of the Big
near Millard, Pike County (Caufield
Pine Mountain, Cumberland Mountain, and the Middlesboro Basin.— This is the region referred to by Fenneman (1938) as the Cumberland Mountain Section. Davis (1921) included it as a part of his area of Creek Bottom Settlements in the eastern mountains. It is the region of the Pine Mountain overthrust, and its western and northern boundary in Kentucky is marked by this and the Russell Fork fault. The Middlesboro Basin, except for greater altitude and corresponding increase in relief, differs in no essential feature from the plateau region west of Pine Mountain. Pine and Cumberland mountains are narrow-crested linear ridges of the Appalachian Ridge-and-Valley type. Pine Mountain is carved out of the eastward-dipping Lee conglomerate, and a section down to the Chattanooga shale is exposed. Its crest ranges from 2100 to 2300 feet at the southern end to 2600 to 2800 feet and locally 3000 feet at the north. Cumberland Mountain similarly has been carved from the westward-dipping Lee on the eastern flank of the Middlesboro syncline, and on its southeastern face a section from the Lee to the Silurian is exposed. Its crest approximates 3000 feet over much of its extent and reaches 3451 at White Rock in southeastern Harlan County. The Middlesboro Basin with its synclinal structure and very thick Pottsville section includes some of the best coal land of the Eastern field. Except marginally, the rocks are flat lying. Within this basin some of the mountains, here of dendritic pattern, rise to high levels. Big Black Mountain on the state line in Harlan County (Big Stone Gap sheet), maintained by the Harlan sandstone, rises in "The Double" to 4150 feet, the highest point in the state. Here the relief exceeds 2500 feet. Log Mountain in Bell County reaches 3200+ feet and local relief is around 2200 feet. Conspicuous terraces have been developed on the more resistant sandstones.
The area is drained by the headwaters of the Cumberland River, Poor Fork to the northeast, and Big Yellow and Clear Fork to the southwest. The river crosses Pine Mountain in a narrow water gap at a level of 1000 feet in a course that was presumably established prior to the etching out of Pine Mountain. Cumberland Gap is well known and is discussed on another page. Pound Gap in Pine Mountain is also used for a main highway. Russell Fork of the Big Sandy flows around the end of Pine Mountain in the Breaks of the Sandy, a deep gorge cut in the Lee.
The Eastern Coal Field is only to a limited extent a commercial crop producer, and the principal crop is corn. Unimproved land1 in 1920 (Davis, 1924) constituted 65.1 per cent of the total with a county minimum of 27.3 per cent and a maximum in McCreary County of 89.4 per cent. A minimum is found on the western edge where production is in the valley bottoms. As long as a large area of forested land was available, the percentage of improved land increased from year to year. With decrease in available land a condition of equilibrium was reached in 1920 (Davis, 1924), with new cleared land just about balancing that abandoned. The region formerly held an important stand of valuable hardwood which has by now been pretty well culled over. At least 50 per cent of the land should be in forest.
Transportation has been a difficult problem. The Kentucky River, and to a limited extent others, have been made navigable with government dams but are of declining importance. Because of topography the development of a highway system has been expensive. The rugged border belt of the Pottsville Escarpment on the west acted as a barrier to access from the west; similarly, the Pine Mountain-Cumberland Mountain belt on the east. These were large elements in the lag in the development of the Eastern Coal Field.
Mineral Resources.—Though not favored agriculturally, the region has been most productive in mineral resources. Coal is outstanding with its best development in the southeastern counties. The coal is somewhat superior to that of the western field and there is more of it. The bulk of Kentucky natural gas production comes from Floyd, Pike, and Martin counties, and only a small part from without the eastern field. The group of oil pools of Lee, Estill, and Powell counties, and again those of the region of the Paint Creek uplift in Johnson, Magoffin, and Lawrence counties have been noteworthy. The clay industry has been developed in many places on a small scale, and the Olive Hill fire clay district is particularly important.
Notes on Physiographic Development (see p. 159).—There exists considerable uncertainty in regard to the identification and correlation of erosion surfaces and cycles of erosion in the Appalachian Plateaus and regions to the east. Attention is called to several points:
(a) The Schooley peneplain, somewhat reduced by subsequent erosion, is commonly recognized as marked by the crest of the Waverly-Pottsville Escarpment (called Cumberland Escarpment in Tennessee) on the west. On the east Pine Mountain is regarded by Fenneman (1938) as most representative and Cumberland Mountain, which is somewhat higher, as having been only imperfectly peneplained. Allowance is, of course, made on all of these levels for monadnocks and later lowering. As such, if the Cumberland Plateau level at ±2000 feet along the Pottsville (Cumberland) Escarpment in northern Tennessee is correctly interpreted as the Schooley level, and similarly the crest of the Waverly Escarpment in Ohio, the decline of the crest of the Pottsville Escarpment northward is a matter of later tilting of this erosion surface. Similarly, the decline in the crest of Pine Mountain from 3000 feet at its northern end to 2100 feet near the Kentucky-Tennessee line is to be interpreted in the same manner. This slope suggests a southward tilt which, in conjunction with the northward tilt of the Pottsville Escarpment, involves a peculiar twisting of this surface on opposite sides of the plateau. Both are topographic features carved out of lower Pottsville sandstones and conglomerates, and to the north the Waverly. Decline of the crest of the Pottsville cuesta northward is at least to some extent a matter of the less resistant character and thinning of the Rockcastle conglomerate in this direction. There is also a great thinning of the Big Lime (St. Louis-Lower Chester) northward and these beds contribute to the forming of the Escarpment. With less effective cap to the north there must have been more rapid recession and lowering.
(b) The lowland belt (pl. XXXVII [Ch. 12]) at the eastern edge of the Pottsville cuesta has a hilltop elevation of 1100 to 1200 feet. Taking into consideration the tilt of the Lexington Plain which brings it to a level of 1600 to 1700 feet (Harrisburg) in the vicinity of Cumberland Gap, these dissected flats are regarded as the product of that cycle.
(c) The lowland centering around Boyd County is an extension of the Worthington plain (Butts, 1904) of West Virginia and western Pennsylvania. It has been regarded as merging with the Lexington plain to the west and thus being its equivalent. In West Virginia and western Pennsylvania it occurs as straths along the main streams 100 to 140 feet below the level of the Allegheny peneplain. Its locally greater development is a matter of the weaker rocks of the Allegheny series.
(d) The Allegheny peneplain has not been well worked out and correlated, and the record of this cycle in Kentucky is not known.
Cumberland Gap topographic sheet (± x ⅓)
topographic sheet (± X ⅓)
1 Land of steep slopes and thin soil, some yet to be cleared, and some abandoned.