The friends had crossed about half the summit of the berg when a sudden gust of wind, forming an eddy, blew up a cloud of ice dust.
These tiny particles stung like needle points when carried by the breeze against the faces of the two boys.
They had to stand still and cover their eyes with their hands.
When the dust subsided they again hurried forward.
At the edge of the ravine a fiercer gust than the first hurled up millions of icy particles.
They glittered like a cloud of diamond dust in the sun's rays.
Wishing to escape, both the lads dropped on to the lower ledge.
"It's worse here than ever," exclaimed Bob, holding his rifle in one hand and placing the other so as partly to protect his face. "Let's get into yonder cave."
They both ran toward it—that is, Jack ran, and Bob hobbled after.
The former had only just time to see that the floor of the cavern sank at a sharp angle, when he felt his feet fly from under him.