iumphed Long Lester.

"And they named the river Lethe. A river that ran down from the melting
glaciers,--though it almost all goes up in smoke, as it were,--in steam,
before it gets out of the hot part. This river whirls along, and in
places the steam actually boils up through the ice water, or along the
banks. I used to think it was an awful pity there were no fish in that
stream, because we could have cooked them without taking them off the
hook."

"Huh!" The old prospector shook his head. "I've thought all along this
here was a fish story."

"But it's gospel truth," Norris assured him. "I mean about the valley. I
_said_ there were no fish. Everything we ate, by the way, had to be
packed in on our backs. It was no place for horses, where in places the
ground fairly shook beneath our feet, and if it were to give way, we'd
find ourselves sure enough in hot water."

"It must have been almighty dangerous," gasped Ted.

"Well, not after we learned the ropes. Sometimes we accidentally put a
foot through a thin place and steam came through. I assure you we stepped
lively then. At other times our feet sank into the soft, hot mud.

"By the way, there is a mountain across the head of the valley that looks
like a crouching dog, and it has been named Cerberus."

"Were those geysers, those ten thousand smokes?" asked the old prospector.

"No, a geyser comes after volcanic activity, while here something is
still likely to happen. A geyser begins as a column of steam and hot
water, which erupts as often as the water gets to the boiling point. It
follows that the water must accumulate in rock not so hot that it would
instantly vaporize it. But the rock underlying this valley is so hot that
no water can accumulate."

"How large are the vents through which the steam comes?" asked Ted.

"All sizes down to nothing at all. There are even a few craters 100 feet
across, that have been produced by volcanic explosions. You will find
these craters, generally, along a large fissure, just the way you find
the Aleutian chain of volcanoes along a fissure in the earth's crust
several hundred miles in length.

"There are fissures all along the margins of the valley, besides those in
the center, and many of these have one side standing higher than the
other, showing them to be earthquake faults,--the same sort of thing we
see here in the rocks of the Sierras. And you should hear the hissing and
roaring of the steam as it forces its way up