April 1, 1904.] 



SCIENCE. 



545 



Louisiana Purchase Exhibition, is based, for 

 the most part, upon the topographic surveys 

 made during the past six years by the Geolog- 

 ical Survey parties. The coast line is taken 

 from the charts of the Coast and Geodetic 

 Survey. The base map, which was also ex- 

 hibited, was compiled by Mr. E. C. Barnard, 

 under the direction of the late Mr. E. U. 

 Goode, and the scale of both the model and 

 the map is forty miles to the inch. In the 

 model the vertical scale has been exaggerated 

 five times, while on the map the contour inter- 

 val is 1,000 feet. This map represents the 

 first attempt to show the relief of Alaska by 

 contours. While much of it will be subject 

 to revision by future surveys, it is believed 

 that in its present form it is of a sulEcient 

 degree of accuracy to be worthy of publication 

 and that it correctly represents the larger geo- 

 graphic features of the territory. 



The coloring of the model is intended to in- 

 dicate, in a broad way, the distribution of 

 timber, as well as that of the ice and snow. 

 Many will be surprised to find what a small 

 part of Alaska is covered with perpetual snow 

 and that the glaciers are practically confined 

 to the coastal mountains of Alaska. It will 

 be noted that the heavy timber is limited to 

 the Pacific coastal belt of Alaska, east of 

 Ivodiak Island, and to the immediate vicinity 

 of the larger rivers of the Yukon Basin. 

 Above the timber line, which in southeastern 

 Alaska is between 3,000 and 4,000 feet, and in 

 the northern part of the territory descends to 

 about 1,000 or 1,200 feet, are broad areas which 

 are entirely devoid of forests. The attempt 

 has been made on the model to represent this 

 treeless region by colors suggestive, at least, 

 of vegetation. 



Besides this high timberless belt there are 

 other large areas of regions of relatively low 

 relief, which are also devoid of timber. These 

 are the coastal plains, which stretch from the 

 Alaskan Peninsula northerly to the Arctic, 

 and thence sweeping around to the north of 

 the Rocky Mountains, extend eastward to the 

 McKenzie. This so-called tundra is a part of 

 the great zone which encircles the polar re- 

 gions. It is devoid of timber except for the 



dense growth of willow which is found along 

 many of the sheltered stream valleys. 



Alaska includes an area of about 570,000 

 square miles, about one fifth of the area of 

 the United States, and two thirds of the re- 

 gion included in the Louisiana Purchase. 

 The shape is irregular and consists of a large 

 compact body of land, with projections to the 

 southeast and southwest, the former called the 

 Panhandle, or southeastern Alaska, and the 

 latter the Alaskan Peninsula. The peninsula 

 is extended to the westward by the Aleutian 

 Chain, to where it is met by the Commander 

 Islands, a somewhat similar easterly extension 

 from the Peninsula of Kamchatka. 



The Pacific and southern Bering Sea coast 

 of Alaska exhibits unusual irregularity of 

 form, including many islands and many 

 fiords which penetrate the mainland. The 

 arctic and northern Bering Sea coast line is 

 much more regvilar, and is characterized by 

 shoal water conditions and straight shore 

 lines. The relief of Alaska exhibits a wealth 

 of contrasting variety in mountains and val- 

 leys, plateaus and lowlands, which are de- 

 veloped on a truly grand scale. Broadly 

 speaking, the larger features of topography 

 correspond with those of the western United 

 States. There is a Pacific Mountain system 

 separated from the Rocky Mountain system to 

 the north by a Plateau Region, and north of 

 the Rockies lies a plains region, forming the 

 Arctic Slope Province. 



The Pacific Motmtain system includes four 

 ranges, the Coast, the St. Elias, the Aleutian 

 and the Alaskan. The highest points in 

 northwestern America and also on the con- 

 tinent lie within these ranges, and are Mount 

 St. Elias, 18,080; Mount Logan (Canada), 

 19,500, both in the St. Elias Range; and 

 Mount Foraker, 17,000, and Mount McKinley, 

 20,300, the two latter in the Alaskan Ranges. 



Less is known of the Rocky Mountain sys- 

 tem, which extends through the Yukon ter- 

 ritory, and upon approaching the Arctic coast 

 bends westward. To the west it is divided 

 into two ranges separated by the valley of the 

 Kobuk River. Between the two mountain 

 systems lies the province which has been 

 called the Plateau Region. This is char- 



