134 GLACIERS OF THE CANADIAN ROCKIES AND SELKIRKS. 



still further absorption. Of the blue and green rays, vvhich make their way 

 readily through the water, only the green rays are reflected by the particles and 

 these alone reach the eye. The quantity of light is thus much reduced in amount, 

 but with the sun shining upon the lake the green becomes quite vivid if the water 

 carries the requisite amount and kind of foreign particles. If the foreign particles 

 were pure white they would be capable of reflecting all colors equally well, and 

 the rich blue of the water would be brought out in perfection. 



In the case of Lake Louise, we have a variable amount of seditnent entering the 

 lake during the year, and consequently a seasonal variation in the color of its water. 

 With the very slack drainage during the winter, the sediment, in considerable part, 

 settles and the water in the spring shows more of its own blue color. With the in- 

 creased activity and melting of the Victoria Glacier the supply of sediment deliv- 

 ered to the glacier increases as the summer advances and the water becomes a richer 

 and richer green. About the delta at the head of the lake the sediment is so abun- 

 ■ dant and lies so near the surface that the water is unable to absorb the yellow, and 

 the color of the sediment itself is seen with little or no modification. In the case 

 of the change in color noted for Emerald Lake we may infer that the drainage 

 stream at its head has been carrying less sediment than fonnerly. It is not 

 improbable that the diminished activity of the inlet may be connected with the 

 stage of diminished precipitation recently closed and that the rich emerald 

 green of the lake in 1888 and earlier was connected with the stage of increased 

 precipitation, which is supposed to have closed in the early 80's. With an 

 increase now in the average annual precipitation it will be interesting to see 

 whether the lake returns to its former shade of color. 



The introduction of green or yellow, organic solid matter, animal or vegetable, 

 into the body of water would have the same efEect. If the lake is svifliciently 

 shallow and the bottom covered with green vegetation, or yellow sediment, 

 the water will not be able in the short transmission to cut out the green and this 

 color may appear in lakes of water free from seditnent. About the margin of 

 Moraine Lake the water has a greenish cast for this reason. Organic matters 

 in solution quite generally give water a yellowish to brownish color, as seen 

 naturally in bogs and artificially in tea, coffee, cider, beer, etc. With the above 

 principles in mind one ma\^ infer from a glimpse of a distant lake the condition 

 of the water and the state of activity of glaciers whose drainage streams empty 

 into it. If upon rounding the shoulder of Mt. Temple, in entering the Valley of 

 Ten Peaks, the first glimpse of Moraine Lake showed that a rich green had been 

 substituted for its superb blue, one might safely infer that the Wenkchemna 

 Glacier had begun to erode its bed although a neighboring rock slide might 

 temporarily give such a result. Even the names of lakes in a glacial region 

 are suggestive of the amount of glacial activity in the valley, such as Sap- 

 phire Lake, Turquoise Lake, and Emerald Lake. 



The same principles of coloring apply to ice as well as to water. When highly 

 charged with sediment of any particular color, its own natural color is obscured 

 and the color of the sediment is sent to the eye with little or no modification. 



