In making the trip down the Big Tuolumne Canyon, animals may be led as far as a small, grassy, forested lake-basin that lies below the crossing of the Virginia Creek trail. And from this point any one accustomed to walking on earthquake boulders, carpeted with canyon chaparral, can easily go down as far as the big cascades and return to camp in one day.
When we have ascended to a considerable height, we see fragments of scoriae sparingly scattered over the surface; until at length, on reaching the summit, we find ourselves suddenly on the edge of a tarn, or deep circular lake-basin called the Gemunder Maar.
At the lake-basin the Collector, after he had surveyed his hay-meadow, went around it to the inlet of the lake with his brown pair of attendants to try their luck, while I botanized in the delightful flora which called to mind the cool sphagnum and carex bogs of Wisconsin and Canada. Here I found many of my old favorites the heathworts kalmia, pyrola, chiogenes, huckleberry, cranberry, etc.
And suppose a place like this, away from the towns, where God's beautiful water is coming down in a hurry, with a cry of power in every leap, where there is a great lake-basin full of material for work, just stored away against men's need for their earning and their building, suppose this place taken and used for the giving of a new chance of life to those who have failed and gone wrong, or have perhaps hardly ever had any right chances.
I must also forego, in the mean time, the pleasure of a full discussion of the interesting question of lake-basin formation, for which fine, clear, demonstrative material abounds in these mountains. In addition to what has been already given on the subject, I will only make this one statement. Every lake in the Sierra is a glacier lake.
In the mean time an incipient lake if produced may be filled up with sediment, and the recently-formed barrier will then be cut through by the river, whereas in a country where glacial conditions prevail no such obliteration of the temporary lake-basin would take place; for however deep it became by repeated sinking of the upper or rising of the lower extremity, being always filled with ice it might remain, throughout the greater part of its extent, free from sediment or drift until the ice melted at the close of the glacial period.
It is admitted on all hands that they were once filled with ice, and as the existing glaciers polish and grind down, as before stated, the surface of the rocks, we are prepared to find that every lake-basin in countries once covered by ice should bear the marks of superficial glaciation, and also that the ice during its advance and retreat should have left behind it much transported matter as well as some evidence of its having enlarged the pre-existing cavity.
Indeed, every feature is more or less tellingly glacial. Not a peak, ridge, dome, canyon, yosemite, lake-basin, stream or forest will you see that does not in some way explain the past existence and modes of action of flowing, grinding, sculpturing, soil-making, scenery-making ice.
Every year, when the rains fall in the great lake-basin of Central Africa, from which one branch of the great river comes, and on the Abyssinian hills, where the other branch rises, the Nile comes down in flood.