“The largest fissure of all, one lying at the foot of Mt. Mageik, is filled with the clear green water of a melted glacier. And above, the mountain smokes away into the clouds!”
“It must be a marvelous place!” said Ace. “I suppose it was regular ice water.”
Norris laughed. “That is the funny part of it. It’s not. The water is actually warm, or rather, tepid, in places, on account of the heat from below.”
“So you had good swimming even in Alaska.”
“We might have had. And then I must tell you about Novarupta. That’s the largest vent in the valley, and it is something you won’t see very many places in the world, a new volcano. It was only formed at the time of the eruption of 1912, and it is one of the largest volcanoes in the world to-day,—with a crater much larger than that of Vesuvius.”
“But Mr. Norris, do y’ mind my asking,” Pedro hesitated, “but how do you know it is a new volcano? Don’t volcanoes sometimes burst forth again after many years of quiet?”
“They do, but there is where the rocks tell the story again. Instead of bursting forth from a mountain top, through igneous rock, (left from the time when the earth-crust was molten), this one erupted in the valley, in sandstone. On a still day, the smoke will rise as high as ten thousand feet.”
Norris, then a student, had been one of the first to view Lassen Volcano when, in 1914, it broke its slumber of 200 years. Indeed, he had had a real adventure, as the second outburst had caught him within half a mile of the crater and he had barely escaped with his life. Of course the boys had to hear all about it.
While the Sierra south of Lassen has been built more through uplift than volcanic activity, at least since the Tertiary period, he explained, the Cascades and indeed, the whole range to the northward through Oregon and Washington, is a product of lava flow.
Happening to be about to start on a camping trip in the Feather River region at the time of the first eruption, he and his companion had hastened immediately to the scene of so much geological history making. The smoke and ashes that billowed forth had been visible for fifty miles, and the accompanying earthquake shocks had been accompanied by a downpour of rain.