THE CENTRAL LOWLANDS. We give this name to the lower lands of the Mississippi basin, although it is but a vague designation. These plains pass gradually up into the plateau on the east. To the north they merge with the smooth lowlands about the Great Lakes, to the south they are continuous with the Gulf lands, and to the west they pass gradually into the high plains west and south of the Missouri River. The region is often called, in the same rough way, the Prairies. See PRAIRIE. THE GREAT LAKE REGION. The lands about the Great Lakes have considerable variety. During the recession of the continental glacier the lakes had higher water levels and often much greater extent than now. During this flooded condition what are now the bordering lands received a cover of such fine muds as are spread upon the bottom of all great bodies of water. To some extent previous inequalities are masked, and the resulting surface is often very smooth and almost level. This is especially true of lakes Ontario, Erie, Huron and Michigan. Some of these lands were treeless and hence were properly called prairies, although modern physiography prefers to designate them as lake plains. Lake Superior is surrounded by older rocks, which have been greatly disturbed and metamorphosed, and the remnants of these ancient mountains form a higher and rougher land than about the lower lakes. This is true of the northern peninsula of Michigan, of Wisconsin, and of northeastern Naturally, therefore, these rocks hold vast stores of iron and copper, while the strata of the prairies offer little in the way of mineral resources except coal. See GREAT LAKES. Minnesota. THE GULF PLAINS. These are most simply defined as a continuation of the Atlantic Coastal Plain, or another part of the younger fringe of the continent. In central Georgia and Alabama the younger formations abut on the older rocks of the southern Appalachians and mark approximately the encroachment of the later seas. By gentle uplift the marginal sea bottoms of the Gulf were laid bare, and form the flat lowlands of this semi-tropical region. This explains in brief the origin of the peninsula of Florida, most of whose surface has now an altitude of less than 100 feet. A gentle uplift of the sea bottom brought this land into existence. Cavernous openings in the rocks, underground streams, and springs of great volume result from the presence of extensive limestone formations as part of the bed rock of the region. The seaward edge of this land abounds in sand bars, coral reefs, and mangrove swamps, and this single State, counting its main shores, its bays and numberless islands, has more than 4000 miles of shore line. It is proposed to open a way for quiet water navigation down the entire east coast of Florida. Westward from Alabama, the Mississippi River (q.v.) becomes the controlling feature in the topography of the Gulf region. The broad Gulf plain occupies a large part of southern and eastern Texas. As in the region to the eastward, the younger rocks have been made into land by uplift and retreat of the sea. As a rule the surface slopes gently toward the Gulf, but with escarpments and great local variations of topography. Some areas are prairie, while others are heavily forested, and the rise to the northwest leads first to the great plateau, or Llano Estacado, and then to the mountains of the Rocky Mountain Range. The shore line is a long crescent, bordered by extensive sand bars, which inclose stretches of quiet water. Galveston is on one of these bars, and it is thus exposed to the Gulf hurricanes. and are THE GREAT PLAINS. This is the name usually given to the lands which rise gradually from the prairies to the eastern base of the Rocky Mountains. But the altitude of these lands is such that they might be called with propriety a plateau. From altitudes of about 1000 feet along the Missouri River in Kansas and Nebraska, they rise to heights of 5000 to 6000 feet at the foot of the western mountains. In general this rise is imperceptibly gradual, but its continuity is sometimes interrupted by escarpments, and the easterly flowing rivers have incised shallow valleys upon the region. The strata are little disturbed and thus the country resembles the prairie region, but the underlying beds are geologically younger overlain in many areas by large bodies of waste, which in part may have been deposited in lakes and in parts was no doubt distributed by torrents from the mountains. Climatic causes have also made the region different in aspect from the prairies The plains are semi-arid in the east and truly arid in the west, and are therefore but sparsely clad with vegetation. quent, the herbaceous vegetation is sparse and has the character of the desert, and agriculture as one goes west is dependent on irrigation. Over large areas the water supply for this purpose is deficient, and grazing is the only remaining resource. This region is a vast one, having the east and west limits already given, and reaching from central Texas to the northern border of the Forests are thus infre country, where it merges into the great Western plains of Canada. In the north the most prominent break in the plains is the Black Hills mountain area. rocks protrudes through the younger strata, giving a region of rugged relief, hard rocks, mines, and forests. In the Black Hills region, in much of the western Dakotas, and in Montana and western Nebraska, are the Bad Lands (q.v.). Here an elevated mass of ancient UPLANDS OF MISSOURI AND ARKANSAS. There is yet to be noticed the most extensive body of elevated land between the Appalachians and the higher levels of the great plains. This lies in Arkansas and westward. In Missouri these uprivers, covered with forests, and known as the lands are of moderate height, dissected by the southern Missouri and in northern and central Ozark Plateau. their metallic deposits, are some low mountains Still better known, owing to of very ancient rocks familiar as Iron Mountain and Pilot Knob. Running through central Arkansas are the Ouachita Mountains. These rise from below the young sediments of the Mississippi Valley, and trend westward, passing through Indian Territory and Oklahoma into northern Texas. This upland region south of the Missouri River, therefore, is associated on various sides with the prairies, the alluvial plains of the Mississippi, the Gulf plains of the South, and the great plains of the West. THE ROCKY MOUNTAINS. The name is properly applied only to an eastern range of the Cordilleran or Western Uplands. The range, with numerous peaks rising above 14,000 feet, ex tends through Idaho, Montana, Wyoming, Colorado, and New Mexico, and sends some outlying ridges into Texas. See ROCKY MOUNTAINS. THE COLORADO PLATEAUS. West of the Rocky Mountains, in Wyoming, Colorado, Utah, New Mexico, and Arizona, is the basin of the Colorado River. This great stream confines its drainage, save near its mouth, to an upland several thousand feet above the sea. Having abundant sources in the rains and snows of the various parts of the Rocky Mountain Range, and rising at great altitudes, it has both velocity and volume, and hence has cut out the great cañons for which it is famous. This is a deeply but only partly dissected region consisting of blocks of strata, cut apart from each other by profound gorges, often intricate in pattern. Being an arid region, the abundant waters are of remote derivation and sunk in the cañons, while the sparse rainfall causes desert conditions to be general, with much exposed rock, little vegetation, and a general absence of conditions favorable to civilized life. Closely associated with these great plateaus are two short but lofty ranges of mountains. One of these is the Wasatch, marking the boundary between the plateaus and the Great Basin, in central Utah. The other is the Uinta Range, about 150 miles in length, and extending from northwestern Colorado through the border lands of Wyoming and Utah. Its chief development is in the latter State and in its east and west trend it departs from the usual direction of American mountain axes. THE GREAT BASIN. This is an area of interior drainage, made up of many minor basins, of which the chief is that of the Great Salt Lake in Utah. See GREAT BASIN. THE COLUMBIA AND SNAKE RIVER PLATEAUS. Large areas drained by these streams in Idaho, Oregon, and Washington are of volcanic origin, and along the Snake River in Idaho and Oregon the lavas form plateaus about 4000 feet in altitude. They are a natural desert, since the region is arid, but are capable of great development under the process of irrigation. ciation with these mountain ranges, reference should be made to the giant and minor volcanic cones which line their trend, and many of whose well-formed summits rise high into the snowline (Shasta, Hood, Rainier, Baker). The coast line of the Pacific is not nearly so great as that of the Atlantic coast, because it is less indented. It has, however, a few of the choicest bodies of inland or protected waters to be found on any shore. Such are San Francisco Bay and Puget Sound, while the deep, tidal Columbia and Willamette rivers offer similar advantages to northern Oregon. It is thus seen that the Cordilleran system is made up of several parallel ranges of mountains, separated in turn by intermontane areas of lofty plateau, or, nearer Pacific Ocean, by broad and fertile lowlands. HYDROGRAPHY. The drainage of the United States may be classed as Atlantic and Pacific. As with the entire continent, and with South America, the smaller ocean receives by far the greater contribution of fresh water from the lands now under review. The Atlantic streams may be considered as belonging to the Hudson Bay, the Gulf, or to open sea drainage. With unimportant exceptions farther west, the Red River of the North carries the contribution of the United States area to Hudson Bay waters. The open sea streams are all of moderate length and volume except the Saint Lawrence, which should be viewed as rising in Minnesota, although locally expanded into lakes of exceptional size. (For details concerning these bodies of water, the reader is referred to the article GREAT LAKES.) All the streams which enter the lakes from the United States are relatively small. Their courses are short, which is equal to saying that the line of water partings between the Laurentian and Mississippi basins is close to the lakes. The divide is also nearly everywhere quite inconspicuous. The streams have thus small capacity for transporting land waste into the lakes. Such waste as reaches the lakes rests in them, a condition from which results the exceeding clearness of Niagara, or of the Saint Lawrence waters that pass the Thousand Islands. The open Atlantic streams, draining that part of the country which is historically oldest, and being often tidal, have a fame and a commercial value out of all proportion to their size. Το begin with the rivers of New England, its conspicuous streams, the Penobscot, Kennebec, Merrimac, Connecticut, and Housatonic, are most of them entered by the tides for many miles. The Merrimac and Connecticut, above tide water, are types of many New England rivers which are interrupted by rapids due to glacial blockade, thus furnishing a great store of water power. THE MOUNTAINS AND VALLEYS OF THE PACIFIC COAST. The features to which reference is here made belong to three States, California, Oregon, and Washington. They will be best understood if it is observed that a single lofty range, the Sierra Nevada, forms the eastern border of California, and that it extends, under the name of the Cascade Range, northward through central Oregon and Washington. Its culminating point, in California, is seemingly Mount Whitney (14,50015,000 feet), which may also be the culminating point of the entire United States south of Alaska. Bordering the sea are lower and younger mountains, constituting also a prolonged range, but New York is composite in drainage. The Hudvariously named, as the Coast Range in Cali- son, with the Mohawk, drains much of its central fornia, the Klamath Mountains in Oregon, and and eastern lands, but is chiefly important for the Olympic Mountains in Washington. (See its tidal course of 150 miles, with great harborage SIERRA NEVADA; CASCADE RANGE, etc.) Between at its mouth, and an open gateway to the west these parallel ranges are lowland valleys of the from the head of tidewater. The Genesee, Black, utmost importance in the development of the and other rivers carry to the Saint Lawrence region. In California there is the great valley much of the run-off of northern and western drained by the Sacramento and Joaquin rivers, New York. The Susquehanna, the Delaware, and the centre of the fruit and grain culture of the the Mississippi take nearly all the remainder of State. In Oregon the Willamette Valley is anal- New York waters. In a most anomalous manner, ogous in origin and in human importance to this, due to glacial change of slope, the Allegheny as still farther north there is the Puget Sound gathers for the Gulf of Mexico waters that fall Valley in the State of Washington. In asso- within a few miles of Lake Erie, |