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And Valleys 282

coal, peat, miles, ridge, land, trees, sec and layers

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AND VALLEYS 282. Places difficult to reach.—To the west of the Great Valley the country changes suddenly. There, one sharp ridge stands so close to the next sharp ridge (Sec. 272, and Figs. 15, 241) that in some of the little valleys there is scarcely room for a wide field. Some of the ridges are so sharp that there is not room on top for even a small field, and the soil is much less fertile than that of the Great Valley. Although some of these valleys are thirty or forty miles long, very little of the land is fit for farms, and not many people live there. Therefore many of the valleys are very much isolated, and some people have abandoned theif farms to go to the more level land in western states, or to mines or towns. Some valleys, however, open out into wide coves of fertile limestone soil, with room enough for a dozen or twenty farrnt, which may be miles and miles from a railroad. One of these valleys, fifty three miles long and four miles wide, is shaped like a canoe (Fig. 236). The only way to get into or out of it without climbing over a high ridge is to fol low the one stream through Logan's Gap, in one of the mountain walls.

In these valleys the only cities are Cumber land, Maryland, and Altoona, Pennsylvania. Each is at a place where a river cutting through the ridges has made a gap through which a railroad line passes across the ridge country to the plateau. The chief industry in both of these towns is repairing cars and engines.

283. Thermal belts and orchfrds.—The Appalachian Ridge district is one of the best places anywhere in the United States to grow fruit, because each ridge is a thermal belt; that is, it has frost drainage. (Sec. 184.) Sometimes the frost line is so sharply drawn that the buds on the trees along the lower side of an orchard may be frozen, while those a little higher up escape frost and make a good crop. Fruit trees on these hillside farms have grown so well that many thou sands of acres of peach and apple orchards now cover the mountainsides near the Potomac River. Orchards are situated at points where the through lines of railway give the fruit farmers a chance to ship their crop eastward to the cities on the Atlantic slope, or westward across the plateau to Pittsburgh and interior cities.

284. Unused land.—There is room enough in the thermal belts on the hillsides to raise many more pe.aches and apples than the markets require. As our population increases, these ridges, with their favorable climate and thousands of square miles of sloping land, may become continuous orchards of crop yielding trees of many kinds (Sec. 87). They

could support prosperous villages which might be connected by good stone roads running the whole length of each valley. We find such wise use of land in Corsica, and in many other European places, even where nature has not given man a climate as helpful as that of our own Appalachians. (Sec. 559.) 285. Coal.—The early settlers in the northeastern end of the Appalachian Ridge region found something in the hillside that they thought was a queer, black stone. It was anthracite, or hard coal, the best kind of coal.

In western Pennsylvania and in the Missis sippi Valley are many thousand square miles of soft or bituminous coal. (Fig. 44.) 286. How coal was formed.—All kinds of coal have the same origin. Coal is made of trees and other plants that grew ages ago. The coal beds were originally swamps in which moss, ferns, and big trees grew and fell down into the water. The trunks, leaves, bark, and moss were kept covered by water, until they slowly turned to peat, which is the first stage of coal. (Fig. 336.) Some times these peat beds became one 'hundred feet thick. Then the land under the peat bed sank down so that muddy water flowed over it, and layers of mud and sand covered the peat. Then more trees grew on the earth that covered the peat, and after a long time they, too, were submerged, making a second layer of peat. Then more mud and sand came on, making an other layer. This process continued a very long time. The pressure of all these layers helped to turn the peat into brown coal or lignite, and then into soft black coal, called bitu minous coal, and to change the layers of.mud and sand into shale or slate or sandstone. To-day in some places there are many layers of stone and coal, one on top of the other. (Fig. 249.) It is very hard for such short-lived beings as we humans are to understand how many millions of years it takes for a bed of peat to be turned into good coal. In various parts of our country we can find coal at one or another stage of development, from the living plant growing in a peat bog to the hard coal ready to burn in stove or furnace. When we burn wood, we get the heat that a tree took from the sun and stored in its trunk years ago. When we burn coal, we get the heat that came out of the sun mil lions of years ago and was stored in the plants of the ancient peat bog.

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