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ill. \C1.\I. STUDIES I N CAN \1>I W R0CKI1 



465 



9. Dirt Bands- A close investigation of this line 1 fig. 72) showed 

 that it marks the junction of two outcropping ice strata, the lower 

 one containing a considerably larger percentage of foreign matter 

 and that it is simply one — the most conspicuous one of a series, the 

 outcropping edges of which give rise to one type ol "dirt bands." 



p IG , j 2 . — Dirt zone, Lefroy glacier, confused with the dirt bands of Forbes. The 

 latter show dimly upon the distant Victoria. 



Such bands normally have a transverse direction upon the glacier 

 and while these extend lengthwise of the Mitre they are normally 

 located with reference to the Lefroy, to which they actually belong. 

 The strata here are too thick to represent successive snowfalls, or 

 even the entire year's precipitation, and such strata must corre- 

 spond to short " cycles " of variable activity of the glacier making 

 agencies. For this phenomenon the term " dirt zone " may be satis- 

 factorily used. 



When viewed from a distance of a half mile, to a mile, the \ ic- 

 toria, opposite its tributary, shows an entirely different and much 

 more significant type of " dirt bands," the original hands of Forbes. 

 Opposite the nose of Alt. Lefroy they appear as straight, transverse 

 bands across the crest of a relatively steep ice slope, passing down 

 which they gradually become more and more convex down stream 



