MA LA SPIN A GLACIER. 225 



ward. The direction of flow in the several lobes explains the 

 distribution of the moraines about their borders. 



The Seward lobe melts away before reaching Yakutat bay 

 and ends with a low frontal slope, but its southern margin has 

 been eaten into by the ocean, so as to form the Sitkagi bluffs. 

 The Agassiz lobe is complete, and is fringed all about its outer 

 border by broad moraines. The Guyot lobe pushes boldly out 

 into the ocean, and breaking off forms magnificent ice cliffs. 



Characteristics of the ?ion- moraine -covered surface. — On the 

 north border of the glacier, but below the line of perpetual snow, 

 where the great plateau of ice has a gentle slope, the surface 

 melting gives origin to hundreds of rills and rivulets which course 

 along in channels of clear ice until they meet a crevasse or mou- 

 lin and plunge down into the body of the glacier to join the 

 drainage beneath. On warm summer days when the sun is well 

 above the horizon the murmur of streams may be heard wherever 

 the ice surface is inclined and not greatly broken, but as soon 

 as the shadows of evening cross the ice fields melting ceases and 

 the silence is unbroken. These streams are always of clear, 

 sparkling water, and it is seldom that their channels contain 

 debris. Where the surface of the glacier is nearly level, and 

 especially when broken by crevasses, surface streams are 

 absent, although the clefts in the ice are frequently filled with 

 water. The moulins in which the larger of the surface streams 

 usually disappear are well -like holes of great depth. They are 

 seldom straight, however, as the water in plunging into them 

 usually strikes the opposite side and causes it to melt away more 

 rapidly than the adjacent surfaces. The water in descending 

 is dashed from side to side and increases their irregulari- 

 ties. A deep roar coming from the hidden chambers to 

 which the moulins lead frequently tells that large bodies of water 

 are rushing along the ice caves beneath. In the southern portion 

 of the glacier, where the ice has been deeply melted, and especially 

 where large crevasses occur, the abandoned tunnels made by 

 englacial streams are sometim.es revealed. These tunnels are 

 frequently 10 or 15 feet high, and occasionally one may pass 



