L26 1. C. RUSSELl L T RFAC] GEOLOGY OF A.LASKA. 



mountain Blopee the vegetation is essentially the same as at St. Michaels. In 

 climbing the Bteep Blopes about Iliuliuk I often had great assistance from the 

 dense mat of vegetation two or three feet thick, which, clingingto the rocks, 



converts their angular crags and shattered crests into s oth domes of soft, 



yielding < >n the Bteep Blopes, as in the swamps, the vegetation is 



always water-soaked, owing to the extreme humidity of the climate in which 

 it thrives. Lakelets are common on slopes and hillsides that would be well 

 drained were it ool for the spongy nature of their mossy hanks. 



About >t. Michaels and on the delta of the Yukon the tundra is typically 

 developed. The characteristics are the abundance of mosses and lichens and 

 the absence of trees. Cryptogamic plants make more than nine-tenths of its 

 mass. On their power to grow above as they die and decay helow depends 

 the existence of the tundra. 



The varied vegetation of these moorlands, although seldom more than a 

 few inches high, is exceedingly luxuriant and beautiful. The soft greens 

 and delicate browns of the mosses and lichens make a most artistic setting 

 for the bright blossoms and glowing fruits of the flowering plants. In some 

 localities, usually in sheltered situations near the lakelets, small groves of 

 alders and dwarf willows reach a height of three or four feet, hut these ex- 

 ceptions to the usual character of the vegetation arc lost to view in the broad 

 treeless expanse. 



On bright Bunny days, and such days are not uncommon in summer on 

 the usually bleak shores of Alaska, a walk on the mossy fields of the tu ml ra, 

 which at a little distance look like luxuriant pastures, is very enjoyable 

 although exceedingly fatiguing. On wild stormy days, when sleet and snow 

 add to the gloom of a leaden sky. and a cold, piercing wind sweeps in from 



the sea, the boundless moorlands, without a sign of human existence, are 



dreary and depressing in the extreme. 



Birds inhabit the tundra in great numbers during the summer, and many 

 species, after t heir long migration-, find t here a congenial home in which to 

 rear their young. The bird life of this peculiar region has been studied by 

 W. II. Mall, L. M.Turner, E. W. Nelson, and others, hut due- not claim 

 our attention a! present, a- only the geological features of the tundra and of 



the general mossy covering of Alaska can be considered in these pag< 



Woa\ of Formation. On making excavations in the tundra, a- well as on 



imining natural sections, I found that the fresh, luxuriant vegetation at 



the Burface changed h\ insensible gradations to dead and decaj ing matter a 



few inches below, and finally became a black, peaty humus.' retaining but 



few indications of \\- vegetable origin. In an excavation made at St. 



Micha< the 13th of July, the t Ira was found to he frozen below a 



depth "f eight inches. Where the moss is more open and more luxuriant, 

 the depth to the frozen Bubsoil was about fourteen inches. 



