ALASKA has an area one-fifth that of the United States, and is the largest of its outlying possessions. Four great physical regions may be recognised : the Pacific Mountains, which consist of a number of ranges running, as a general rule, more or less parallel to the coast, the Central Plateau, a rolling upland deeply dissected by the Yukon and its tributaries, the Rocky Mountains, which border the Plateau on the east and north, and the Arctic slope, which is a continuation of the Mackenzie Plains. The geological structure of these different regions is as yet imperfectly known, and the rocks of those districts which have been examined vary in age from Archman to Quaternary.
In considering the climate of Alaska it has to be noted that the country falls within the same parallels of latitude as the greater part of Scandinavia, and like Scandinavia lies on the western side of a continental land mass. On the other hand, the configuration of the North Pacific is less favourable than that of the North Atlantic for the northerly movement of warm water. Where its influence is experienced on the coastal regions as far as Bering Strait, cool summers and mild winters prevail, while the precipitation is heavy, generally being over 100 inches. In the interior, the range of temperature is much greater, and the com paratively few observations which have as yet been made indicate that the mean temperature for January is considerably below zero, while that of July is between 55° F. and 60° F. The precipitation is light, and probably does not exceed 20 inches. On the upper slopes of the mountains, and on the coast lands beyond Bering Strait, the climatic conditions are generally of an Arctic nature.
The vegetation of the country is also varied. As far west as 152° W. the seaward slopes of the Pacific mountains are clothed to a considerable height with spruce, hemlock, and cedar ; while in the river valleys of the plateau country there are larger areas covered with spruce and poplar, hemlock and birch. The bulk of the timber, however, seems more suitable for fuel and for temporary use in the mines than for permanent building purposes. Under the
climatic conditions which prevail agriculture can never be exten sively pursued, and is never likely to do more than supply in part the needs of a mining population. Grain only ripens under the most favourable circumstances, but vegetables and hay are raised in large quantities, and numbers of cattle are reared.
The main incentive to the economic development of Alaska is the abundance of its mineral resources. Of these, the most important is gold, the output of which now amounts in value to nearly one-fifth of the total gold output of the United States. The chief producing areas are Juneau in south-east Alaska, near the lower end of Lynn Canal, where lode-mining is carried on in the Treadwell district, Seward Peninsula, which is in the main a region of placer mining, and Fairbanks, also with placer deposits, in the valley of the Tanana, a tributary of the Yukon, at present the most productive district in the country.
Although the production of other minerals is progressing but slowly, it is known that there are large supplies of copper in the coast region south of the Pacific mountains, notably in the country round the Copper River. Coal, chiefly bituminous and lignitic, is abundant, but, owing partly to its inferior quality, and partly to the difficulty of transport, it has not yet been worked to any con siderable extent. The most valuable seams are believed to be those in the vicinity of Controller Bay.
The fisheries of Alaska come next in importance to its minerals. Salmon are most abundant, but halibut, cod, and herring are also obtained. Seals are caught off the Pribilov Islands.
The chief means of communication in the country is the Yukon river, which is on an average open for a period of between four and five months. The railway from Skagway to White Horse offers a good route into Alaska ; and there are several lines of local importance within the country itself.