ntains for the light
of a campfire, but there was no light to be seen. The Pony Rider Boys'
campfire, however, was blazing up brightly, they having built up a large
fire on purpose to attract the attention of the men who had made the
smoke signals from the low mountain peak, low in comparison with the ten
and fifteen thousand feet ranges about them. The boys turned in at
midnight, a late hour for them, and were sound asleep within two minutes
thereafter. They were aroused an hour later by the most terrifying roar
they had ever listened to.

"What's the matter?" cried Tad, springing from his tent, trying to
pierce the darkness with his gaze.

"Is--is the world coming to an end?" yelled Ned.

"I guess the mountain is falling down," shouted Stacy.

"Guide, guide!" roared the Professor.

Anvik, drawing his blanket still more closely about him, stepped over
and threw some fresh sticks on the fire. The roaring by this time had
become a thunderous, crashing noise that fairly deafened them. One had
to shout to make himself heard. Fine particles, like sharp stones, began
raining down upon them, stinging the faces, causing the boys to shield
their eyes with their arms. Stacy, in alarm, ran and hid in the tent;
the others stood their ground, yet not knowing what second they might be
caught in what seemed to them to be a great upheaval of nature.

"It's an earthquake," shouted Ned Rector.

Stacy heard the words in a brief lull. The fat boy burst from his tent
yelling like a wild Indian.

"An earthquake! Oh, wow, wow, wow! We'll all be shot to pieces. Oh,
help!"

Tad grabbed the boy by a shoulder, giving him a good shaking.

"Stop that noise!" he commanded. "Don't yell until you are hurt."

"I want to yell now. Maybe I can't yell after I'm hurt," returned
Chunky.

"Guide! What is it?" roared the Professor, the perspiration standing out
over his face, as Tad observed when the fire blazed up.

Anvik finished what he was doing before he answered. Then he spoke
without looking up.

"Him mountain fall down."

"Is it an ice slide?" shouted Tad.

"Ugh!"

"An avalanche, do you mean?"

"Yes; an ice-avalanche," explained the Professor. "I have seen them in
other parts of the world."

"Sun make him ice weak; ice fall down," explained Anvik.

"How about danger for us?" asked Walter.

For answer the Indian shrugged his shoulders and went on poking the
fire. Then, of a sudden, there came a crash like a salvo of artille