a mine.

From the tunnel his eye traveled up the face of the white mountain to the
great snow-comb that yawned over the edge of the rock-rim far above. It
had snowed again heavily all night, and now showed symptoms of a thaw. Not
once nor twice, but a dozen times, the man's anxious gaze had swept up to
that great overhanging bank. Snowslides ran every year in this section
with heavy loss to life and property. Given a rising temperature and some
wind, the comb above would gradually settle lower and lower, at last break
off, plunge down the precipitous slope, bringing thousands of tons of rock
and snow with it, and, perhaps, bury them in a Titanic grave of ice. There
had been a good deal of timber cut from the shoulder of the mountain
during the past summer, and this very greatly increased the danger. That
there was a real peril the man looking at it did not attempt to deny to
himself. It would be enough to deny it to her in case she should ever
suspect.

He had hoped for cold weather, a freeze hard enough to crust the surface
of the snow. Upon this he might have made shift somehow to get her to
Yesler's ranch, eighteen miles away though it was, but he knew this would
not be feasible with the snow in its present condition. It was not certain
that he could make the ranch alone; encumbered with her, success would be
a sheer impossibility. On the other hand, their provisions would not last
long. The outlook was not a cheerful one, from whichever point of view he
took it; yet there was one phase of it he could not regret. The factors
which made the difficulties of the situation made also its delights.
Though they were prisoners in this solitary untrodden caynon, the sentence
was upon both of them. She could look to none other than he for aid; and,
at least, the drifts which kept them in held others out.