through these fissures from
the hot depths beneath. Sometimes it looks like blue smoke, it is so full
of gases, especially sulphur dioxide, the gas that is given off by
burning sulphur. So the popular notion of Hades isn't so far off after
all, eh?"

"Could you smell the sulphur fumes?"

"Sometimes, yes,--when the other gases did not overwhelm the odor. But
the weirdest part of all is the incrustations along the borders of the
vents. All colors of the rainbows--shapes as fantastic as anything in
fairyland. Lots of yellow, of course, from the sulphur,--crystals of it,
some of them neighbor to an orange tinted crystal, lying in the blue mud.
It was a beautiful color combination. Then there were green and gray
alum crystals which looked like growing lichens. There were also deep
green algae actually growing. Strange how certain designs are used over
and over again in nature! In other places the mud is actually burned
brick red, especially where the fumaroles are burnt out. This shades to
purple, and in other places to pink. But the most surprising, perhaps,
were the white vents just tinted with a delicate pink or cream.

"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