228 THE JOURNAL OF GEOLOGY. 



become filled with fine debris and the adjacent surface is lowered 

 by melting, the material thus concentrated acts as do large bowl- 

 ders, and protects the ice beneath. But as the gravel rises in 

 reference to the adjacent surface, the outer portion rolls down 

 from the pedestal on all sides, and the result is that a sharp 

 cone of ice is formed, having a sheet of gravel and dirt over its 

 surface. These sand cones, as they are called, sometimes attain 

 a height of ten or twelve feet, and form conspicuous and charac- 

 teristic features of the glaciers over large areas. 



The surface of Malaspina glacier over many square miles, 

 where free from moraine, is covered with a coral -like crust which 

 results from the alternate melting and freezing of the surface. 

 The crevasses in this portion of the vast plateau are seldom of 

 large size, and, owing to the melting of their margins, are broad 

 at the surface and contract rapidly downward. They are in fact 

 mere gashes, sometimes ten or twenty feet deep, and are 

 apparently the remnants of larger crevasses formed in the glaciers 

 which flow down from the mountains. Deeper crevasses occur 

 at certain localities about the border of the glacier, where the 

 ice at the margin falls away from the main mass, but these are 

 seldom conspicuous, as the ice in the region where they occur 

 is always heavily covered with debris and the openings become 

 filled with stones and bowlders. The generally level surface of 

 the glacier and the absence of large crevasses indicate that the 

 ground on which it rests is comparatively even. Where the larger 

 of the tributary glaciers join it, however, ice falls occur, caused 

 by steep descents in the ground beneath. These falls are just 

 at the lower limit of perpetual snow and are only fully revealed 

 when melting has reached its maximum and the snows of the 

 winter have not yet begun to accumulate. 



Moraines.- — From any commanding station overlooking Mal- 

 aspina glacier one sees that the great central area of clear, white 

 ice is bordered on the south by a broad, dark band formed by 

 bowlders and stones. Outside of this and forming a belt con- 

 centric with it is a forest -covered area, in many places four or 

 five miles wide. The forest grows on the moraine, which rests 



