« PreviousContinue »
usually impracticable. If sluiced out of the highest reservoir, it gathers in the next below, and so on through whatever system may have been developed. If, perchance, it should pass the last reservoir, the silt is then free for deposit in the navigable stretches of the stream. Regardless of whether there are reservoirs, the ultimate deposit of the detritus is in the navigable sections, whence its removal can be accomplished only by a steam dredge at the expense of the Govern
In the degree that the forests are damaged on the high watersheds, then, inevitable damage results to water power and navigation through increased extremes of high and low water and through vast deposits of gravel, sand, and silt in the stream channels and in any rersevoir which may have been constructed.
CONDITIONS IN THE SOUTHERN APPALACHIAN MOUNTAINS.
The Southern Appalachian Mountains contain approximately 9,900,000 acres, having an elevation above 2,500 feet.
The Blue Ridge and Great Smoky Mountains consist of an elevated plateau walled in on its western margin by a higher mountain range and with numerous short ranges projecting above its general surface. In one of these, the Black Mountains, Mount Mitchell rises to 6,711 feet, the highest altitude east of the Rocky Mountains. The eastern edge of the plateau is formed partly by peaks rising above the general surface and partly by an abrupt descent that forms an escarpment overlooking the Piedmont Plateau. Over 40 peaks, including approximately 6,400 acres, have an altitude of over 6,000 feet, and 54,000 acres are above 5,000 feet. The ridges of these mountains are rounded, the slopes precipitous, and the valleys deep cut and narrow. In Virginia the Blue Ridge narrows to a single range of a few miles. width, but retains its characteristic topography. It crosses the Potomac River at Harpers Ferry, extends through the State of Maryland, and merges into the Allegheny Mountains in southern Pennsylvania.
The Allegheny Mountains extend southward from Pennsylvania and form the mountainous part of West Virginia and that portion of Virginia lying near the West Virginia boundary. The highest peak of the Alleghenies is Spruce Knob, in Pendleton County, W. Va., 4,860 feet.
The Cumberland Mountains are simply the extension of the Alleghenies and are considered to begin at the northeast boundary of Kentucky. From this line they extend southwest through Kentucky, extreme western Virginia, Tennessee, and into northern Alabama. The Cumberlands are of less elevation than the Alleghenies. Their highest peak is Big Black Mountain, in Harlan County, Ky., which has a height of 4,100 feet.
The greater part of the Southern Appalachian region is underlain by rocks that weather into soils which are easily eroded when exposed on deforested slopes. Erosion varies in character on account of the different kinds of soil. In some places the entire surface rapidly wears away, each freshet removing a thin layer, so that the fertile soil is soon exhausted. The field is at last worn out and abandoned.
This kind of erosion occurs on close-grained, compact clay soils, the particles of which cling together firmly and resist the downward cutting of small currents of water.
Another type of erosion results in parallel gullies extending straight up and down the slopes. As these gullies grow deeper they widen, the smaller ones are obliterated.by the larger until they become of huge size, their bottoms sharp, their sides steep, and their edges irregular and jagged. Such erosion results from clay soils of homogeneous texture and somewhat softer and more loamy than the type mentioned above. It is a very common type, and the process once started can be stopped only with great difficulty. It nearly always results in the early abandonment of the field on which it begins.
Of all types of erosion, that of gullying, in which rapid down-cutting is accompanied by undercutting and caving, is the most rapid in its progress and the most difficult to check, as well as the most destructive in its effects. This type occurs in soils of relatively soft micaceous subsoil. The surface may be a fairly compact clay that offers moderate resistance to water, but once broken a gully results in the soft subsoil. It rapidly deepens, the micaceous material on the sides is easily undermined and slips in, leaving vertical or overhanging walls. Into such gullies many square yards of soil may cave during a single heavy rain, and as the decomposed micaceous material is usually scores of feet in thickness such gullies frequently become chasms of great depth and width. This kind of erosion when started on cleared land may advance into a forested area and undermine even the largest trees. The rocks which produce soil subject to this kind of erosion are found over a large part of the Southern Appalachian region, and especially in the Blue Ridge Mountains.
Still another type of erosion is that started by small landslides, which occur on steep slopes when the soil is saturated during periods of prolonged rainfall. Such landslides are often started by the tramp
of cattle over the steep slopes during wet weather. One animal in climbing up or down a slope may start a number of such slides, each of which usually grows in width and length and soon makes a great bare scar in the field.
The soils subject to serious erosion are very extensive in the Southern Appalachian region. Where on such soils nature has placed a forest that brings about a balance between rainfall and run-off, the danger in widespread clearing is obvious. The loss resulting from erosion means not only the loss of the soil from the fields; it means also the loss which has already been described in the failure of water power and navigation.
While in the Blue Ridge and Great Smokies no valuable coal deposits are known to exist, these mountains have a great variety of mineral resources. Many of them have never been developed, while others have become the basis of important mining operations. Large investments have been made in the mining of copper, marble, mica, corundum, talc, asbestos, slate, kaolin, and other minerals, and the mineral products are said to amount to several million dollars annually.
Such mining as is carried on does not require large quantities of timber, since but a small part of it is underground mining, and some
of that which is underground is carried on in the ancient crystalline rocks, which do not require timbering. The influence of such mining upon the forests is not very important except in a few instances where great damage is done. The most pronounced example of injury by mining is at Ducktown, Tenn., where sulphur fumes from the roasting and smelting of copper ores have killed all vegetation for a number of miles around. The perfectly bare surface has eroded with wonderful rapidity. It is a striking illustration of the completeness of destruction that may result from erosion in this region when the protecting forest cover is once removed.
In the Alleghenies and Cumberlands the mining of coal overshadows all other mining operations. This is one of the richest coal fields of the United States. The great mines which have been developed require annually millions of feet of timber, and will continue to require great quantities so long as the coal supply lasts.
Coal mining does not necessarily conflict with the proper use of the forest. It requires the use of usually less than 10 per cent of the surface, and this generally in the valleys. All the rest can be kept in timber. Moreover, the ownership and control of the surface do not necessarily go with the control of the coal rights. In many cases the companies which work the mines control only enough of the surface to enable them to operate the collieries.
In the northern part of Virginia the Blue Ridge is composed of sandstone which gives rise to the DeKalb stony loam, for the most part a poor, thin, stony soil. The summits are rough, rocky, and sharp-crested, while the slopes are steep and rocky. Probably 95 per cent of this type is uncultivated, and is valuable only for the timber it supports. The Blue Ridge, with its outlier, Short Mountain, is well defined, and soils suited to agriculture come to its base. Immediately across the Potomac, in western Maryland, similar conditions prevail. Farther south, in Virginia, the Blue Ridge soils are much more productive, and it is only the steep upper portions that are unsuited to farming. These higher areas are so steep, rough, and rugged that they are adapted only to forestry.
In western North Carolina, east of the Blue Ridge, lies a succession of foothills with moderately precipitous slopes and with small valleys between.
To the eastward lies the great agricultural Piedmont Plateau, from which little valleys follow back through the foothill region and into the mountains. At first these valleys are adapted to general farming, but as the region becomes more rugged they are pinched out and the soil is unsuited to cultivation.
ONLY SMALL AREA ADAPTED TO ORCHARD GROWING.
Where the Blue Ridge supersedes the foothills, many orchards have been planted on the better soils, and it is these in part which have given to western North Carolina the reputation of producing good fruit-a reputation justly deserved and capable of being much extended.
The success of apple orchards on soils and locations as already described, however, caused plantings to be made at greater and greater elevations, on very steep lands. As a result, orchards in such places are much less profitable than twenty years ago, simply from the increase in cost of labor, and eventually this item will, and in fact does already, make it impossible to compete in the production of apples with other areas where the decrease in the amount of labor necessary will more than offset the additional cost of land more economically worked. But even more striking is the problem of insect and fungus attacks. It is not economically feasible to plant orchards in the eastern United States where the land is so steep that the orchards can not be effectively sprayed at a reasonable expense, and the fact that this has been done in some cases in the past argues nothing for its probable success in the future.
Again, on some of these steep lands orchards have been planted at so great an elevation that the yield of fruit has been much lessened, the bloom having been destroyed or the trees winter-killed more often than at a more moderate elevation. The climate, then, goes hand in hand with the steep and rugged features and the character of the soils of large areas in this region to render their use for other than forest purposes impracticable.
The Great Smoky Mountains lying to the west and southwest of the Blue Ridge are generally rough and valueless for any purpose except the growing of timber. Throughout the higher mountains cultivation is impracticable because the soils rapidly erode when cleared and farmed. The sand and gravel washed from the mountain fields are carried down in large quantities to the lower courses of the streams in the piedmont region and deposited on valuable agricultural lands, rendering them valueless. Single floods will occasionally leave deposits several feet in thickness.
In the Cumberland Mountain region the soils are naturally much less productive than on and east of the Blue Ridge. They are more similar to the soils of the Great Smoky Mountains, being derived principally from sandstone. On the top of the escarpment which borders the Tennessee Valley on the west, the character of the topography is less rugged. The soils spread out more in the form of tablelands, which often include areas of level to moderately rolling land. The underlying rock, however, is so resistant to weathering that the soil has seldom accumulated to much depth, and often it is very stony from the fragments of sandstone. As a result, in many places these soils are ill suited to agriculture. When of sufficient depth to constitute agricultural land, moderate crops can be grown, but the soil is not naturally very productive and requires a good deal of fertilization. Transportation in this region also presents a difficult problem. The railroads have followed the little valleys, leaving the broad uplands between them, from which they are separated by a steep escarpment of 1,000 feet or more, in an isolated location; hence the possibilities for practicable and profitable agricultural development in this region are very limited.
The Southern Appalachian forests fall naturally into three typescove, slope, and ridge-each with peculiar characteristics. The soil in the coves is usually deep, moist, and fertile. The naturally good conditions are supplemented where unaffected by fire by a deep, partially decomposed layer of humus, which increases the moistureholding capacity and prevents erosion. Yellow poplar, maple, and hemlock are strictly limited to the coves. Black walnut and black cherry once occupied the cove land also. It is in the coves that the Southern Appalachian forest attains the greatest variety and luxuriance. It is here that growth is most rapid and the best quality of timber is produced. The situation is also best for lumbering, hence it was that the first cuttings of the Appalachian forests were in this type.
The slopes have a better-drained soil than the coves, but one which is less fertile. The maple, hemlock, and poplar of the coves give way on the lower slopes to oak, chestnut, and hickory, where these species have their most perfect development. White oak extends all the way from the coves to the summits of the ridges, but on the slopes it does best.
The ridges have a dry, stony soil and an exposed situation which distinctly affects the kind and quality of their timber. The more valuable trees of this type are chestnut, chestnut oak, black and red oaks, and sometimes white oak and white pine. The severe conditions result in scrubbier timber than is found on the slopes and unfit the ridge lands to be handled profitably for the production of saw timber. The lumbering of the ridges for the production of telephone poles, railroad ties, tanbark, and extract wood is profitable, but on account of the slow growth of the timber on the ridges the lumberman generally does not consider it profitable to cut conservatively and protect the young growth for a second crop.
DAMAGE THROUGH CLEARING.
Originally the forest covered almost the entire Southern Appalachian region. Due to clearing for agriculture, the forest is now confined to the mountains and to the valley lands which are stony, cut into steep hills, or wanting in fertile soil. All the best valleys are cleared. The fields in many places extend far up the mountain sides, frequently even to the summits.
In clearing land, only the undergrowth and small trees as a rule are removed. The large trees are killed by girdling and left standing. One frequently sees fields worn out and abandoned before the girdled trees have fallen. New ground is usually cleared beside the abandoned field and the same destructive process repeated. In places may be seen three successive clearings-new, still cultivated, and abandoned--with the dead trees still standing on all of them.
Clearing virgin forests for farms is going on steadily from year to year to replace worn-out, eroded, and abandoned lands. Always the movement is toward the higher lands, those lower down having finished their course.
Many small tracts, reaching thousands of acres in the aggregate, unsuited for either tillage or grazing, have been cleared, especially