Shrubs also hasten in time to the new
gardens,--kalmia with its glossy leaves and purple flowers, the arctic
willow, making soft woven carpets, together with the heathy bryanthus
and cassiope, the fairest and dearest of them all. Insects now enrich
the air, frogs pipe cheerily in the shallows, soon followed by the
ouzel, which is the first bird to visit a glacier lake, as the sedge is
the first of plants.
So the young lake grows in beauty, becoming more and more humanly
lovable from century to century. Groves of aspen spring up, and hardy
pines, and the Hemlock Spruce, until it is richly overshadowed and
embowered. But while its shores are being enriched, the soil-beds creep
out with incessant growth, contracting its area, while the lighter
mud-particles deposited on the bottom cause it to grow constantly
shallower, until at length the last remnant of the lake
vanishes,--closed forever in ripe and natural old age. And now its
feeding-stream goes winding on without halting through the new gardens
and groves that have taken its place.
The length of the life of any lake depends ordinarily upon the capacity
of its basin, as compared with the carrying power of the streams that
flow into it, the character of the rocks over which these streams flow,
and the relative position of the lake toward other lakes.
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