ICE CLIFFS ON WHITE RIVER 201 



If a concise definition of a glacier be accepted, such isolated 

 masses of l)uried ice would hardly be included, being in fact a part 

 of and closely related to the frozen subsoil which is found nearly 

 ever3^wliere in the Arctic province. Moreover, the deposits which 

 overlie the ice, as described by Mr Gorman and observed by the 

 writers, are soils and silts, and entirely non-glacial. If tbese ice 

 masses were buried remnants of ibrmer glaciers, then would be asso- 

 ciated with tliem glacial material. 



Speaking of recent volcanic activity in the valle}^ of White River, 

 Mr Gorman makes the surprising statement that not a trace of the 

 volcanic ash which forms so noticeable a feature at the banks of the 

 Yukon is to be seen along the banks of the White, except near the 

 mouth. If he had possessed even a slight familiarity with the region 

 in question or with the literature* of the subject, he would have 

 known that many hundred square miles in the Upper White River 

 basin are covered with this volcanic ash, with many local drifts from 

 50 to 100 feet in depth. The ash covers both valley bottoms and 

 mountain tops. 



The thin stratum shown in the banks of the Yukon is merely the 

 attenuated eastern edge of the deposit which reaches its maximum 

 in the region from which Mr Gorman says it is entirel}^ absent. We 

 entirely agree with his dissent from Heilprin's theory that the ash 

 was deposited in a lake bed covering the upper Yukon basin, but on 

 quite different grounds from those which he adduces. 



A final case of su]ierficial observation remains to be noted. Mr 

 Gorman states that the water of White River is " surcharged with a 

 mixture of line blue clay and granitic sand " which gives it the char- 

 acteristic white color from which it derives its name. INIany of the 

 upper tributaries are glacial streams, and hence carry rock flour and 

 glacial i)ebbles like other streams of similar origin, but this constitutes 

 only a small })r(jportion of the sediment. IMuch the larger part consists 

 of the light pumiceous volcanic ash whicli covers the upper half of 

 the basin, as was proven by a microscopical examination of the sedi- 

 ments. Reing entirely unconsolidated and only in ])art covered by 

 vegetation, it is rapidly eroded, and on account of its low specific 

 gravity large (juantities of relatively coarse material remain in suspen- 

 sion in the water. 



♦An Expi'ilition 'I'IiiomkIi the Viikoii liistrii't, \<\>. llc-l.-.d; Kxpldiatiniis in AlMska, p. (lit. 



