26 



JifATUEAL HISTORY CJLLBOTIOXS IN ALASKA 



district, lu Alaska, viz : Gorvus caurimis, Trochilus rufus, Empidonax difficilis, and Buteo borealis 

 calurus. The soutliern half of this district is occupied by the Thlinket Indiaus, who are gradually 

 replaced by Eskimo iu the western part of the district as the climatic and other conditions of life 

 become more severe. 



(2) Aleutian District. 



Commencing at the Shumagin Islands and the western and southern coast of Aliaska Penin 

 snla, this district includes all of the great Aleutian chain of islands extending about 900 miles 

 or more to the westward with the Pribylov, or Fur Seal group, included. These islands extend in 

 a long curve, and divide the waters of the North Pacific from those of Bering Sea. Between the 

 islands a swift tidal cnrrent runs back and forth, forming tide-rips about the reefs and islets. The 

 Shnmagins and the coast of the peninsula are low, but the general character of the islands is mount- 

 ainous. The islands are not large as a rule, and the largest two of the group, Unimak and 

 Unalaska, are only about 60 by 30 miles in their greatest extent. The shore line of the islands is 

 much cut up by bays and projecting reefs, and on most of them the mountains begin to rise abruptly 

 from the shore. The flanks of the hills are rolling, and an occasional valley or comparatively level 

 plateau is found. The islands are of volcanic origin, and a number of volcanoes are still slightly 

 active. The highest peaks in these islands are from four to eight thousand feet high. 



The islands are entirely destitute of trees, and the only bushes are dwarf willows and a few 

 others, which rarely reach 5 feet in height. The mild damp climate causes a luxuriant growth of 

 grasses, flowering plants, and three or four species of ferns in dry situations along the lower valleys 

 and sheltered places within two or three hundred feet of the sea level. Above this sphagnum 

 mosses and other northern plants begin to predominate, and gradually become more scanty, until, 

 according to Chamisso, the limit of vegetation is reached — 2,450 feet above the sea. The snow 

 line is about 3,500 feet above the sea. The climate ig mild as compared with other regions in the 

 same latitude, but the almost continuous cloudy or stormy weather and the extremely common 

 occurrence of fierce gales, often accompanied by rain or snow, render the climate one of the most 

 disagreeable in the world. Observations taken by the Eussians at Unalaska Island for the five 

 years ending in 1834 give an average annual temperature of 37o.8. The minimum temperature 

 observed during that period was 0°, and 77° the maximum, or a total range of 77°. Iu 1828 the 

 mean temperatures of the seasons were, spring, 36o.6 ; summer, 51°.5 ; autumn, 38°. 7; winter, 

 360.27. This mild temperature is due to the warm waters of the North Pacific, which inclose the 

 islands at all seasons. Ice never forms except on the inner bays, and even at the Pribylov group 

 sea ice rarely forms; in winter these islands form the southern limit of the ice-pack of Bering Sea, 

 which never comes within sight of the Aleutian chain proper. Upon the Pribylov Island, St. 

 Paul, — 12° has been recorded, being the lowest temperature known to the writer as having 

 been observed within the limits of this district. 



The perpetual cloudy weather on the islands of this district can be best appreciated by refer- 

 ence to the following table, the result of seven years' observations at Unalaska. 



The rainfall in this district has been placed at between 27 and 40 inches, but the h'gh winds 

 prevent a satisfactory determination: 



Month. 



Jamiary . 

 February 

 March . . . 



April 



May 



Jane 



Month. 



July 



August 



September 



October 



November 

 December , 



The above table gives a total, in seveu years, of 53 clear days, 1,263 partly clear days, aud 

 1,235 totally cloudy days. Snow falls in all but one or two months iu the year, but never remains 

 long on the ground within 100 feet of the sea level. 



During May and in October, 1881, while the Corwin lay in Unalaska Harbor, about fifty 

 species of flowering plants were observed, mainly distributed among the following genera : Umpe- 



