Over their tops rise faint wreaths of yellowish clouds and the mephitic odor becomes more pronounced.
"At last!" shouts Carmen, as we reach the end of the trail.

"At last! _Amigo mio_, we are saved!" Before us stretches a wide treeless waste like a turf moor, with a background of sombre forest.

The moor, which is broken into humps and hillocks, smokes and boils and babbles like the hell-broth of Macbeth's witches, and across it winds, snake-wise, a steaming brook.

Here and there is a stagnant pool, and underneath can be heard a dull roar, as if an imprisoned ocean were beating on a pebble-strewed shore.

There is an unmistakable smell of sulphur, and the ground on which we stand, as well as the moor itself, is of a deep-yellow cast.
This, then, is the _azuferales_--a region of sulphur springs, a brimstone inferno, a volcano in the making.