THE VARIATIONS OF GLACIERS 667 



than 200 feet of debris, which he takes to be all morainic. This ice 

 occurs under what has been called the Moraine Mesa, as its surface 

 is covered by a well marked ground moraine. Mr. Sylvester looks 

 upon the material below this moraine as an earlier moraine; between 

 the two is a confused mass of forest humus and broken trees, some of 

 which seems still to be in place ; and he infers two periods of glaciation 

 separated by a long interval with a mild climate. The present 

 writer, who visited the mountain in 1901,' looks upon the lower material 

 as ejecta. The presence of ice under it would then indicate that an 

 older glacier was buried under the material thrown out during a 

 period of great activity; and the steam which would continue to 

 escape, in gradually diminishing quantities, would prevent the forma- 

 tion of glaciers for a long time; even after the snow again began to 

 accumulate, it would require a century or more before the White 

 River Glacier would extend to the region of the Moraine Mesa; and 

 no great variations of the climate would be necessary to account for 

 the buried forest. It is not improbable that the great outburst was 

 the cause of the disappearance of the southern wall of Mt. Hood's 

 crater. 



Mr. George Davidson made a trip in southeastern Alaska in 1907 

 and noticed a general retreat of the glaciers and diminution of the 

 snow-fields since his earlier visits in 1867-69. The only definite 

 information we have regarding Glacier Bay is contained in two short 

 notes by members of the International Boundary Survey.^ A small 

 sketch map of Muir and Reid Inlets accompanies Mr. Morse's report. 

 These notes show that between 1894 and 1907, Muir Glacier has 

 retreated eight miles, Grand Pacific Glacier, seven and one-half 

 miles, and Johns Hopkins Glaciers, three miles. Only a small 

 part of the end of Muir Glacier is discharging ice-bergs. ^ That 

 the rapid retreat common to all the glaciers of the bay was in 



1 "The Glaciers of Mt. Hood and Mt. Adams," Mazama, 1905, Vol. II, pp. 194- 

 200; and "Studies of the Glaciers of Mt. Hood and Mt. Adams," Zeitschrijt jilr 

 Gletscherkunde, 1906, Vol. I, pp. 113-32. 



2 Otto J. Klotz, "Recession of Alaskan Glaciers," Geog. Jour., 1907, Vol. XXX, 

 pp. 419-21; Fremont Morse, "The Recession of the Glaciers of Glacier Bay, Alaska," 

 Nat. Geog. Mag., 1908, Vol. XIX, pp. 76-78. 



3 It is to be noted that Mr. Klotz interchanges the names of the Grand Pacific 

 and the Johns Hopkins glaciers. 



