36 H. F. Reid— Studies of Mair Glacier. 



been noticed among the Swiss glaciers by Forbes and by Agassiz 

 as a seasonal change, the glacier partly flowing away during the 

 summer and thickening up again during the winter. The loss 

 incurred in this Avay by the Muir glacier in the summer is not 

 made up during the ensuing winter, for the clifl'erence in level 

 just mentioned is far too great to have been produced in one 

 season. 



The stratified deposits on the shores of Muir inlet are covered 

 by a thin layer of moraine a foot or two thick ; scarcely thicker, 

 in fact, than the moraine which covers the end of the glacier. 

 If the ice had not retreated rapidly this deposit would have been 

 much thicker. The mass of detached ice mentioned by Professor 

 Wright has entirely disappeared. 



The moraines extending from the lakes in Main valley to Muir 

 inlet seem explicable only on the supposition that this valle}^ 

 once contained a glacier tributary to the Muir, and that the sup- 

 plies of snow having diminished in this region more rapidly than 

 in the northwest this tributary has diminished much more 

 rapidly than the Main glacier, until now the flow is actually 

 reversed. The two moraines issuing from Granite canyon and 

 flowing one into Main valley and the other into Muir inlet are 

 also due to the same cause. The moraine extending from ^to 

 the ice-front, and composed of material quite different from the 

 granitoid rock of H, is readily explained by the former greater 

 thickness of the ice. The moraine which comes from the first 

 northern tributary probably flowed just over H, and when the 

 ice here was not very thick the very steep southern face of H 

 must have caused a break in its continuity, so that the ice and 

 moraine fell over this slope to the surface of the glacier below. 

 . The accumulation of detritus here is the source of this moraine, 

 and it has not yet been entirely carried off. 



In a valley connecting the western side of Muir inlet with the 

 upper part of Glacier bay there lies a small glacier which we 

 have called Dying glacier. It is about 3 miles long, slopes both 

 eastward and westward, and has moraines running from end to 

 end. It has no real feeders, although a tributary joins it on the 

 south. It must be the remnant of a much larger glacier, deriv- 

 ing its supplies from the lateral valleys ; probably also, perhaps 

 principally, from the great ice stream which filled the upper part 

 of Glacier bay, with which it must have had connection. At 

 present its highest point is 760 feet above tide, an elevation much 



