Page:The New International Encyclopædia 1st ed. v. 17.djvu/236

ROCKY MOUNTAINS. 212 ROCKY MOUNTAINS. quently cxceeiliiiyly boautilul laUes of the Rocky ilountain region arc due to the work ot glacial ice. Those near the crests of the liiglier ranges are, for the most part, rock-basins, while those at lower altitudes, and especially the long, nar- row lake's in the larger valleys, are lieid by luorainal dams. The chief industry throughout the Rocky Mountains from Alaska to Alcxico is mining, and silver, gold, copper, and coal are the le|^ing products. Next in importance is stock-raising, and particularly cattle-raising, for which the nu- tritious bunch grass, growing mostly l)elow the lower limit of the forests, furnishes abundant nourishment. In recent years, however, over- grazing has greatly injured the natural pas- ture lands south of Montana. Agriculture is of local importance, and with certain exceptions, mostly in western Idaho and adjacent portions of Washington, is dependent on irrigation. All through the region from the central part of British Columbia to Central Mexico there are ranches, mining camps, villages, and cities. At present seven railroads, six in the United States and one in Canada, cross the chain, and another to the north of the Canadian Pacific Railroad is projected. In Mexico the main avenues of traffic run north and south through the intermontane valleys, as is shown by the Mexican Central Railway, wdiich connects Ciudad Juarez, opposite El Paso, Texas, with the City of Mexico, a dis- tance of over 1000 miles. These several rail- roads and their numerous branches make acces- sible nearly all portions of the Rocky Mountain region, except the extreme north and the exces- sively rugged western portion of the tableland of Mexico. At the far north, however, a new centre of industry has developed in the Klondike region. The forests of the mountains are economically important, not only as a source of hnnber, but also because they serve to regulate the flow of streams used for irrigation. For these reasons 21 forest reserves, with a total area of over 38,000 square miles, have been established in the portion of the Rocky Mountains belonging to the United States, and similar provisions have been made in Canada. Among the economic assets of the Rocky iloun- tains should also be included their magnificent scenery and healthful and invigorating climate. Although thousands of people visit them each year in search of health and recreation, the great benefits to be reaped in these directions are as yet only partially appreciated. The portions most attractive to travelers are the Yellowstone National Park and the Grand Canon of the Colo- rado, each of which is unrivaled in its class. Flora. The Rocky Mountains constitute one of the great floral regions of North America. With the exception of southern New Mexico and Arizona, which belong botanically to the Mexican Plateau, and the extreme northern portion, whose flora is still but little known and merges with that of the Pacific Coast, the flora of the whole Rocky Mountain region is essentially homogene- ous at corresponding altitudes. On the other hand, the region is markedly different from the Eastern or Appalachian region. Scarcely 20 per cent, of the Rocky Mountain plants are found in the East, and of these most belong to the species common to both hemispheres. The Rocky Moun- tain flora, however, includes numerous, species found in the contiguous regions, and is especially allied to that of the California or Sierra Nevada ri'giun. Within certain altitudes forests occur throughout the Rocky Mountain region. The upper limit of tree growth, or cold limber line, rises toward the south, having an elevation of 9000 feet on the international boundary and 11.000 to 12.000 feet in Colorado. In the Stony and Park Jlountains and thence southward there is also a lower limit of tree growth, determined mainly by lack of humidity. As far north as Idaho and soutlicrn Wyoming the larger valleys are below this dry timber line, but in Canada the forests are continuous across mountain and val- ley. The forests of the whole region are over- whelmingly coniferous, and with the exception of two alpine junipers none of the coniferous trees are common to the Appalachian region, though the latter has closely allied corresponding species, some of which have been erroneously identifiecl with those of the Rockies. There are about 10 pines, and the most characteristic tree of the whole region is the Western yellow pine (Pinus poiiderosa) . The nut pine {Pinus edulis) and the Pinus Chihuahua are the chief species con- fined to the southern portion, while the moun- tain pine {Pinus monticola) and the black pine {Pinus Uurrayana) are found chiefl}- in the north. Of the spruces the Picca Eufjelmanni is the most common throughout the region, though generally seeking higher altitudes (nearly 9000 feet in the south). Other spruces, notably the Picea Columbiana, are more common in the north, and a northern habitat is also preferred by the firs (Abies irrandis and nobilis) , the Western Hem- lock ( Tsitga Merten-siana ) , and the tamarack {Larix Americana) . Shrubby conifers, such as junipers, are found chiefly in the arid south- western ranges and above the timber line. The deciduous forests of the Rocky Mountains are of small extent and poor in species. There are six species of oak. but all rather small and scrubby, and the other deciduous tree families are simi- larly ill represented. Sycamores, the New Mexi- can locust, and mulberries grow in the south, and the rivers throughout the region are lined with Cottonwood, balsam poplar, and willows. On the level plateaus the predominating flora is of the sage-brush type, represented by the genera Artemisia. Atriplex, Eurotina, and Bigelovia, but in the southwest the plains are nearly desert, with the characteristic desert flora. Above the timber line the Alpine flora closely resembles the flora of the Arctic region. Among all the flower- ing plants of the Rocky Mountains the families best represented are in the order named, the Compositiie, Grarainefe, Papilionacese, CyperaceEe, Ranunculaceoe, Cichoriaceoe, Polygonace.T?, Ona- graceoe, and Umbellifeme. Of these the first two together include about 25 per cent, of all the species. F.vrNA. It was the opinion of the earlier students of animal life in North America that the Rocky Mountains were the central and essen- tial part of a peculiar fauna representing the 'Central' zoogeographical region embracing the whole elevated territory between the Great Plains and the base of the Sierra Nevada. It appears, however, that such a distinction does not exist : that the Roclcy Mountains are peculiar only in such features as depend upon altitude and are correlated with climate and vegetation as locally determined by height above the sea and conse- quent low temperature. The fauna of all North