456 HARRY FIELDING REID 



explorations and surveys of Alaska, and several glacier regions have 

 been mapped. A number of glaciers north of Juneau are in rapid 

 recession. The glaciers in the neighborhood and north of the head- 

 waters of the Copper River (in the neighborhood of latitude 63^° 

 N and longitude 145 W) seem to be retreating slowly (Brooks). 



Fresh moraine, extending for nearly two miles at the end of 

 Nabesna Glacier, shows that it is retreating rather rapidly. The 

 Chisana Glacier, 15 miles to the east, has a very clean end; a com- 

 parison of photographs taken in 1899 and 1908 shows surprisingly 

 little change in the aspect of the glacier, though at one place a 

 slight recession has taken place. Frederika Glacier, entering White 

 River valley from the north, when seen by Dr. C. W. Hayes in 1891 

 ended "in a nearly vertical ice cliff .... about 250 feet high. 

 At the foot of the cliff there is a small accumulation of gravel and 

 ice fragments apparently being pushed along by the advancing 

 mass." 1 In 1909 Mr. Stephen R. Capps says "its surface is 

 remarkably smooth and slopes down evenly to a thin edge in 

 front." The Frederika Glacier has evidently changed from an 

 advancing to a retreating glacier in the interval. Exactly opposite 

 Frederika Glacier another glacier, in retreat in 1891, is now 

 advancing. 2 



Such spasmodic cases are probably produced by sudden acces- 

 sion of material due to avalanches or land slides, rather than to 

 simple variations in snow-fall or temperature. 



The Ruth Glacier, rising on Mt. McKinley and extending many 

 miles to the east, is slowly diminishing in size (Rusk). 



Professor U. S. Grant and Mr. D. F. Higgins have published a 

 general map of Prince William Sound, showing the location of all 

 the glaciers, on a scale of 4 inches to the mile. 3 They have also 

 published descriptions, pictures, and detailed maps of the ends of 

 several of these glaciers. 4 The last observations were made in 



1 "Expedition through the Yukon District," Nat. Geog. Mag. (1892), IV, 153. 

 2 "Glaciation on the North Side of the Wrangell Mountains, Alaska," Jour. 

 Geol. (1910), XVIII, 56. 



3 " Reconnaissance of the Geology and Mineral Resources of Prince William 

 Sound, Alaska," U.S. Geological Survey, Bulletin No. 443, Washington, 1910. 



4 " Glaciers of Prince William Sound and the Southern Part of the Kenai Peninsula, 

 Alaska," Bull. Amer. Geog. Soc. (1910), XLII, 721-33. 



