GLACIERS OF THE CANADIAN ROCKIES AND SELKIRKS. '33 



and red, are absorbed if passed through water of sufficient thickness. While of 

 the colors at the other end of the spectrum, with the short wave-lengths, blue is 

 the one which water is chiefly able to transmit, violet and green being also trans- 

 mitted, but less perfectly. Bodies of pure water of a volume sufficient to absorb 

 the longer waves of light reflected from the bottom, but not so deep as to absorb 

 it all, will appear blue. This blue is not reflected from the sky, although the con- 

 dition of the sky will affect the tint. Lakelets in the neVe", such as the one dis- 

 covered upon Sapphire Col by Mr. Wheeler, are a rich blue; those upon the ice 

 may be blue, or not, depending upon their freedom from sediment, being liable 

 to change rapidly. Moraine Lake (plate xxv) owes its exquisite blue color to its 

 purity and depth. Water in the form of ice possesses still the same power 

 to transmit the colors with the shorter wave-lengths, violet, indigo, blue and 

 green, with the preference for blue. If a mixture of these four colors, or of all 

 the others which compound white light, be passed through a block of pure ice, 

 of sufficient thickness, none but the blue will emerge. If no light whatever is 

 being transmitted through either ice, or water, it will look black, or will show 

 whatever color of light is being reflected from its surface. 



From this blue as the fundamental and natural color of ice and water by 

 transmitted light we meet with many modifications in nature. Finely divided 

 ice, as snow and ne"ve", presents innumerable reflecting surfaces from which light 

 of any and all colors is sent to the eye. The same is true of water lashed into 

 foam, or in any finely divided state, as fog, cloud, or condensed steam. In 

 ordinary light these forms of water and ice appear white, but in the gorgeous 

 colors of the sunrise and sunsets they transmit to the eye by reflection the greatest 

 variety of color. Ne"ve" begins to show a bluish tinge as soon as the transmitted 

 light begins to predominate over that which is being reflected. The water which 

 issues from the glacier is generally charged with sediment, and if this is much 

 in amount, its color will determine the color of the water of the drainage brook. 

 It generally appears a milky, or creamy, white but may be a dirty gray. With 

 the deposition of the coarser yellowish sediment and the retention of the very 

 finest, if the volume of water is considerable, the water assumes a greenish tinge, 

 as seen in the Asulkan and Illecillewaet streams. With the loss of this sediment 

 the stream acquires more and more of its natural blue. When this glacial sedi- 

 ment is introduced into a lake in sufficient, but not too great, quantity the water 

 becomes charged with finely divided rock particles in suspension. These 

 particles are able to reflect the longer waves of the spectrum, particularly yellow, 

 but also the closely related green and orange, while they very effectually cut out 

 the shorter wave-lengths giving rise to violet, indigo, and blue. The result is that 

 there are introduced into the water innumerable reflecting faces which are capa- 

 ble of sending to the eye only those colors that lie at the centre of the spectrum 

 and towards the red end. But the only light that is available for reflection is 

 that which has already passed through the water once and had its yellow, orange, 

 and red to a greater or less extent filtered out. That which remains to be 

 reflected by the foreign particles will pass again through the water and will suffer 



