536 A. M. BATEMAN KENNECOTT GLACIER OF ALASKA 



deposition of silt is now taking place and is unquestionably forming 

 stratified layers. 



The stratified silt, overlain by boulders and till, was shown to the satis- 

 faction of the writer to have been brought about under present glacial 

 conditions clearly in the one glacial period, and in all jDrobability within 

 a few years. Such an occurrence, if remote from the present glacier, 

 might hastily be interpreted as representing a glacial recession and ad- 

 vance or else a second glacial period. 



MELTING AND DISCHARGE 



Melting proceeds over all parts of the glacier, but is most rapid along 

 the edges. No exact data are available as to the wastage on the top, 

 though it appears to be little more than the annual accretion. Guide 

 stakes stuck in shallow cracks to a depth of a foot were observed to stand 

 up over the summer seasons. 



All of the discharge takes place from the front of the glacier; no con- 

 tinuous marginal streams exist. Probably 75 per cent of the discharge 

 emanates from the "pot-hole." This is a circular hole immediately in 

 front of the glacier, which emits a column of water that is the source of 

 Kennecott River. The depth of the hole is unknown. Usually the col- 

 umn of water rises a few feet above the level of the surrounding ground, 

 but at times a giant column of water spouts up to a height of 15 to 20 

 feet. This "playing" of the "pot-hole" is interestingly coincident with 

 the disappearance of Icy Lake, some 11 miles up the glacier (see figure 3). 

 This lake lies on the west side of the glacier, where the wall of ice forms 

 a dam directly across the right-angled tributary valley of Hidden Creek. 

 The water of the creek impounds against the ice-dam and forms a lake, 

 one-half mile wide and one and one-half miles long, the surface of which 

 is covered by innumerable icebergs. Every autumn, and often in the 

 spring, the lake suddenly disappears, and repeated observations show that 

 almost simultaneously the pot-hole begins to "play." This establishes a 

 direct subglacial connection between the lake and the pot-hole for a dis- 

 tance of 11 miles. The connection is also capable of transmitting a part 

 of the pressure under which the water rises. 



The volume of water in this subglacial stream is large. It also carries 

 an abundance of glacial sand and gravel and is thus highly competent to 

 produce corrasion. An interesting question arises as to whether such 

 streams may produce an appreciable subglacial incision of the valley floor, 

 and also if in large glacial valleys some of the cutting attributed to post- 

 glacial processes may not have been formed in part during the later 

 glacial stages of such subglacial streams. 



