24 



Sierra Club Bulletin. 



moraine was not then visible ; and the suggestion that the 

 moraine was then concealed by snow is discountenanced 

 by the fact that the neighboring Lyell Glacier was quite 

 as free from snow in the summer of 1883 as in 1903. 

 While the evidence is not altogether conclusive, I regard 

 it as probable that the ice Johnson saw at the margin of 

 the lake was actually continuous with and part of the 

 glacier, and that the glacier has retreated several hun- 

 dred yards since the making of his map. 



One of the best methods of recording the position of 

 a glacier-front is through photography, and this method 

 is by far the most available. Points of view should be 

 chosen which command the relation of the ice to fixed ob- 

 jects of the landscape, and especially to objects imme- 

 diately in front of it. To enable the future photographer 

 to reoccupy the same station, and thus secure the best 

 possible view for purposes of comparison, the spot 

 should be marked in some way, as by the building of a 

 cairn ; and it is well to include in the view something of 

 the immediate foreground. Both these means of identi- 

 fication are available in the case of the views of Lyell 

 and McClure glaciers. It is of primary importance to 

 record with the photograph the date of its taking. This 

 should include not only the year, but the month and day, 

 for it is probable that most glaciers undergo an annual os- 

 cillation. It is well to make two negatives from each 

 station, timing and developing one so as to show the 

 details of the ice, and the other to show the details of 

 rocks and other dark objects. The best month for such 

 records in the Sierra is probably September, because at 

 that time the outline of the ice is lease apt to be obscured 

 by snow. 



