46 THE MOUNTAINS OF CALIFORNIA 



longest, belonging to the loftiest summits, stream 

 perfectly free all the way across intervening notches 

 and passes from peak to peak, while others overlap 

 and partly hide each other. And consider how 

 keenly every particle of this wondrous cloth of 

 snow is flashing out jets of light. These are the 

 main features of the beautiful and terrible picture 

 as seen from the forest window ; and it would still 

 be surpassingly glorious were the fore- and middle- 

 grounds obliterated altogether, leaving only the 

 black peaks, the white banners, and the blue sky. 

 Glancing now in a general way at the formation 

 of snow-banners, we find that the main causes of 

 the wondrous beauty and perfection of those we 

 have been contemplating were the favorable direc 

 tion and great force of the wind, the abundance 

 of snow-dust, and the peculiar conformation of the 

 slopes of the peaks. It is essential not only that 

 the wind should move with great velocity and 

 steadiness to supply a sufficiently copious and con 

 tinuous stream of snow-dust, but that it should 

 come from the north. No perfect banner is ever 

 hung on the Sierra peaks by a south wind. Had 

 the gale that day blown from the south, leaving 

 other conditions unchanged, only a dull, confused, 

 fog-like drift would have been produced; for the 

 snow, instead of being spouted up over the tops 

 of the peaks in concentrated currents to be drawn 

 out as streamers, would have been shed off around 

 the sides, and piled down into the glacier wombs. 

 The cause of the concentrated action of the north 

 wind is found in the peculiar form of the north 

 sides of the peaks, where the amphitheaters of the 



