I . . . RUSSEL1 1 I ; I \ ' I GEOLOGY OF \ I V.SK A. 



_'r:i|iliic picture of what must have existed in the Sierra N< vada and some 

 other -imilar ranges during the Glacial epoch. A careful study of whal is 

 now taking place in these ice-covered mountains would no doubt go far 

 toward explaining many of the records of glaciation found in regions where 

 glaciers do nol m>\\ exist. 



The glacii about the head of Lynn canal, like those <>n the sid- 



the valley of the Taiya, present great variety. Some of 1 1 1 « ■ larger amphi- 

 theatres are drained by veritable rivers of ice several miles in length, which 

 ive tributaries from neighboring slopes and lateral canons. Many oi 

 the ice ms specially those in the smaller cirques, are not drained by 



well-defined ice streams, but like the secondary glaciers of the Alps, described 

 by Forbes, and the existing glaciers of the High Sierra of California, form 

 tongues of ice which have all the characteristics of the larger glaciers, 

 pting that topographic conditions limit their growth. 



In some instances secondary glaciers of considerable Bize occur on steep 

 mountain slopes, without any indication of an amphitheatre or depression 

 beneath them. These ice bodies frequently appeal- as convexities on the 

 mountain Bide, fully exposed to the sky on all Bides. .Many of the neV<5 fields 

 about Lynn canal, as is common in all ice-covered mountains, are drained 

 by several glaciers. The icestreams flowing from Bnow-fields near the cresl 

 of the mountains in some instance a drain both north and south, and contrib- 

 ute on melting both to Taiya river, which reaches the sea within half a 

 dozen miles, and t « > 1 1 1 • - Yukon, the mouth of which is two thousand miles 

 away. 



Above the snow-fields there are many spires and minarets of shattered 

 rock which hear no evidence of ice abrasion. These bold pinnacles occur 



•ecially along the rims of ice-filled amphitheatres, and are ihe most prom- 

 inent where the walls of two or more depressions unite. The -pin- projecting 

 above the neve* are frequently bo slim and tapering that they look like tree 

 trunk- when viewed from the valley- below. The angular and unabraded 



udition of the extreme summits of these mountains agrees with what may 

 In- Been ahum the mure lofty summits of the High Sierra, and illustrates still 

 farther what must have been the condition of that picturesque region at the 

 time it was Bhrouded in glacial ice. 



One of the most Btriking features of the high, ice covered region of south- 

 \ ii i- furnished by the clouds and vapor-wreaths that nearly always 



• n< ii < ii- the i n tain-, or rise mill- in height above them. Even on bright 



sunny days, when thi - clear and blue, the moisture borne upwards by 



the warm aii m the valleys i- cundeii-cd and forms cloud-maSSi 



which roll upwards with fleecy whiteness like thunder-cape in temperate 

 latitude! I forme of these vapor-wreaths and the blue 



-had- i on the Bnow imparl estion of life and motion to the 



