The Theory of Glacier motion. 71 



water thus formed percolates through the cold mass below 

 and expels the air entangled in the snow, the liquid trickles 

 down and gets frozen on to the granules which it meets 

 with colder than itself, augments them in size, and cements 

 them together." By this process, assisted by the consoli- 

 dating influence of pressure, there is formed a mass of 

 white, opaque, frozen and consolidated, half snow half ice, 

 the whiteness and opacity being due to the myriad air 

 bubbles which it encloses. 



This white opaque mass is what the French call n&oe 

 and the Germans Firn. Its superficial layers are more 

 snowy and white, and consist of nearly pure snow, while the 

 deeper ones have more colour and consistence, and break 

 on the larger scale into vast fragments, which are called 

 seracs. The upper part of the neve is stratified, each 

 stratum representing a considerable distinct snow-fall, but as 

 we pass down into the more condensed and more solid ice, 

 these signs of stratification disappear^ and it assumes a 

 homogeneous and more or less granular consistency. 



"The granulated structure of the neve I' says Forbes, "is 

 accompanied with the dull white of snow passing into a 

 greenish tinge, but rarely, if ever, exhibiting the transparency 

 and hue of the proper glacier. The crevasses in the neve 

 are wider and more irregular than in the proper glacier ; 

 the colour transmitted by them is green ; the substance of 

 the neve is much more easily fractured than ice, and is also 

 more readily thawed and water worn, and it often contains 

 huge caverns, in which are pendent icicles ten and twenty 

 feet in length." Gradually the neve passes, as we descend 

 into true glacier-ice, blue in colour, and close and trans- 

 parent in texture. 



It is important to note, and to remember, that glacier 

 ice is, in internal structure, very different to ordinary ice 

 made by freezing water in a pond or laboratory. It is 

 formed out of granulated neve^ and it never loses the 



