The joyful, songful streams of the Sierra are among the most famous and interesting in the world, and draw the admiring traveler on and on through their wonderful cañons, year after year, unwearied. After long wanderings with them, tracing them to their fountains, learning their history and the forms they take in their wild works and ways throughout the different seasons of the year, we may then view them together in one magnificent show, outspread over all the range like embroidery, their silvery branches interlacing on a thousand mountains, singing their way home to the sea: the small rills, with hard roads to travel, dropping from ledge to ledge, pool to pool, like chains of sweet-toned bells, slipping gently over beds of pebbles and sand, resting in lakes, shining, spangling, shimmering, lapping the shores with whispering ripples, and shaking over-leaning bushes and grass; the larger streams and rivers in the cañons displaying noble purity and beauty with ungovernable energy, rushing down smooth inclines in wide foamy sheets fold over fold, springing up here and there in magnificent whirls, scattering crisp clashing spray for the sunbeams to iris, bursting with hoarse reverberating roar through rugged gorges and boulder dams, booming in falls, gliding, glancing with cool soothing murmuring, through long forested reaches richly embowered,—filling the grand cañons with glorious song, and giving life to all the landscape.
The present rivers of the Sierra are still young, and have made but little mark as yet on the grand cañons prepared for them by the ancient glaciers. Only a very short geological time ago they all lay buried beneath the glaciers they drained, singing in low smothered or silvery ringing tones in crystal channels, while the summer weather melted the ice and snow of the surface or gave showers. At first only in warm weather was any part of these buried rivers displayed in the light of day; for as soon as frost prevailed the surface rills vanished, though the streams beneath the ice and in the body of it flowed on all the year.
When, toward the close of the glacial period, the ice mantle began to shrink and recede from the lowlands, the lower portions of the rivers were developed, issuing from cavelike openings on the melting margin and growing longer as the ice withdrew; while for many a century the tributaries and upper portions of the trunks remained covered. In the fullness of time these also were set free in the sunshine, to take their places in the newborn landscapes; each tributary with its smaller branches being gradually developed like the main trunks, as the climatic changes went on. At first all of them were muddy with glacial detritus, and they became clear only after the glaciers they drained had receded beyond lake basins in which the sediments were dropped.
This early history is clearly explained by the present rivers of southeastern Alaska. Of those draining glaciers that discharge into arms of the sea, only the rills on the surface of the ice, and upboiling, eddying, turbid currents in the tide water in front of the terminal ice wall, are visible. Where glaciers, in the first stage of decadence, have receded from the shore, short sections of the trunks of the rivers that are to take their places may be seen rushing out from caverns and tunnels in the melting front,—rough, roaring, detritus-laden torrents, foaming and tumbling over outspread terminal moraines to the sea, perhaps without a single bush or flower to brighten their raw, shifting banks. Again, in some of the warmer cañons and valleys from which the trunk glaciers have been melted, the main trunks of the rivers are well developed, and their banks planted with fine forests, while their upper branches, lying high on the snowy mountains, are still buried beneath shrinking residual glaciers; illustrating every state of development, from icy darkness to light, and from muddiness to crystal clearness.
Now that the hard grinding sculpture work of the glacial period is done, the whole bright band of Sierra rivers run clear all the year, except when the snow is melting fast in the warm spring weather, and during extraordinary winter floods and the heavy thunderstorms of summer called cloud-bursts. Even then they are not muddy above the foothill mining region, unless the moraines have been loosened and the vegetation destroyed by sheep; for the rocks of the upper basins are clean, and the most able streams find but little to carry save the spoils of the forests,—trees, branches, flakes of bark, cones, leaves, pollen dust, etc.,—with scales of mica, sand grains, and boulders, which are rolled along the bottom of the steep parts of the main channels. Short sections of a few of the highest tributaries heading in glaciers are of course turbid with finely ground rock mud, but this is dropped in the first lakes they enter.
On the northern part of the range, mantled with porous fissured volcanic rocks, the fountain waters sink and flow below the surface for considerable distances, groping their way in the dark like the draining streams of glaciers, and at last bursting forth in big generous springs, filtered and cool and exquisitely clear. Some of the largest look like lakes, their waters welling straight up from the bottom of deep rock basins in quiet massive volume giving rise to young rivers. Others issue from horizontal clefts in sheer bluffs, with loud tumultuous roaring that may be heard half a mile or more. Magnificent examples of these great northern spring fountains, twenty or thirty feet deep and ten to nearly a hundred yards wide, abound on the main branches of the Feather, Pitt, McCloud, and Fall rivers.