Gradually the ground firms as more humus is created and more silt is trapped. The area becomes meadow, supporting grasses, sedges, and other flowering plants. Trees begin to reinvade the drier ground, and eventually the meadow reverts to forest. Centuries may be required to see this cycle through, from forest to pond, to bog, to meadow, to forest again. At each stage many of the animal inhabitants change: the song of the western robin and the chatter of a red squirrel in the original, pre-beaver forest give way to the croak of a heron; the heron is replaced by the insect-and-berry-eating cedar waxwing; the waxwing is followed by the tree-dwelling western robin and red squirrel. Lakes Cold and Deep Seeming to skate on its own reflection, a spotted sandpiper comes in low over the quiet water, wingtips almost touching the surface of the lake. It alights at the shore and folds its wings. Amid the rounded rocks, this plain but elegant little shorebird is all but swallowed up. Teetering constantly on long legs, it sets off along the water’s edge, pecking here and there, coming closer and closer, never forgetting to stop and curtsy, as if acknowledging, while hurrying offstage, the applause of an audience. As it draws near, several water striders skate away from the shore. A stonefly, scuttling between two rocks, is deftly speared. So large a morsel makes the bird pause and rough its feathers, then scamper into the water to take a drink. Teetering again, it passes in front of me and continues down the shore, where I soon lose sight of it rounding a rocky point. I am sitting at the foot of Lake McDonald, watching the darkness gather over the valley, seeing the last light slide upward to the tips of the distant mountains. As daylight dissolves, this long fleet of familiar peaks seems almost to glide toward darkness, slow and silent as sailing ships. The sheet of motionless water stretches many kilometers away between tree-covered moraines. The water is deep and cold. No emergent plants line the barren shore. It would seem that no life, except for the single gull that rests on the water far away, exists in this nearly thousand-meter-high lake. ■ Considering the great volume of Glacier’s large, deep lakes, the life they support is indeed meager. A large part of the reason lies with the nature of their shores, where almost no plants grow. A combination of factors prevents the development of a lush shoreline growth. Contoured like bathtubs, these steep-sided lakes exhibit narrow or non-existent shoreline shallows, which are vital for the production of rooted plants. Strong wave action and extensive seasonal fluctuations in the level of these natural reservoirs prevent the development of emergent water plants in locations where they might otherwise be expected.