A little before noon, they were in the rocky vestibule of the canyon.

On either hand, the walls rose almost sheer, while their road, now, was but a narrow shelf under the overhanging cliffs, below which the white waters of the stream--cold from the snows so far above--tumbled impetuously over the boulders that obstructed their way--filling the hall-like gorge with tumultuous melody.

Soon, the canyon narrowed to less than a stone's throw in width.

The walls grew more grim and forbidding in their rocky nearness.

And then they came to that point where, on either side, great cliffs, projecting, form the massive, rugged portals of the mountain's gate.
First seen, from a point where the road rounds a jutting corner on the extreme right, the projecting cliffs ahead appear as a blank wall of rock that forbids further progress.