Through rifts in the nearer ranges there are glimpses of pine-clothed peaks, which, towards twilight, pass through every shade of purple and violet. The sky and the earth combine to form a Wonderland every evening—such rich, velvety coloring in crimson and violet; such an orange, green, and vermilion sky; such scarlet and emerald clouds; such an extraordinary dryness and purity of atmosphere, and then the glorious afterglow which seems to blend earth and heaven! --Isabella Bird, A Lady's Life in the Rocky Mountains (1879)