“I did, but only four great ones. There were two away back in the age of invertebrates.”
“Then has the climate been the same since the last ice age?”
“Not at all. The change is gradual, and geologists naturally conclude that some time we will have another ice age. We’ll hope man has found a better way to keep warm by that time. Our climate, with all its ups and downs, is little by little, through the centuries, growing colder!”
“And how do you know about all these ups and downs of climate?” challenged Long Lester.
“Why, for one thing,—we don’t have to read it all from the rocks,—there is a plain story in the rings of growth in the Big Trees. Don’t you remember those cut stumps, and the thousands of rings we counted, one for a year? And some were wider than others, because in those years there had been more rainfall.”
“Well, I never!” was all the old prospector could articulate, as all hands once more called it a day.
Next day Ace searched in concentric circles, but without finding a trace of Mexicans, or, indeed, of any one.
The next night found the little party encamped an eight hours’ hike up the side of another glacial polished slope. The trail,—that is to say the way they picked to go,—led first to the upper end of the canyon and over the rocks that bordered a green-white water-fall. The wind blowing the spray in first one direction and then another, they got well wetted, though the clear California sunshine soon dried them again. But the most curious part of their climb past the falls was the rainbow that persisted in following them till they seemed to be at the hub of a huge semicircle of opalescent tints.
Above, (perhaps eight hundred feet higher than their camp at the hot spring), they came to where the river slid green and transparent over granite slopes just bordered by a fringe of pine. The water ran deep and swift, though, and as Ted stooped to drink, he found that, rhythmically, a larger swell, (call it a wave), would slap him in the face, till once, blinded by the unexpected onslaught, he all but lost his balance. It would have been inevitable, had he done so, that he should almost instantly go hurtling over that eight hundred foot drop, whose waters roared till the boys had to shout at each other to be heard even a few paces away. But the water was deliciously icy, from its fountain-head in the glacier above.
Wide slopes just steep enough to make climbing demand considerable sure-footedness widened this hanging valley on either side, with no greenery save the picturesque bits that grew along the weathered cracks. Beyond this, the canyon walls continued to rise abruptly.