hundreds of feet below, unearthly retching; and, in a moment, it
would all come up again, belched out with an explosive force that
hurled a boiling spray of mud so high that we rushed down the slope.
A single drop of it would have burned like molten lead. Five minutes
of this was enough; and even now, when I reflect that every moment,
day and night, the same regurgitation of black slime is going on, I
feel as I have often felt, when, on a stormy night at sea, I have
tried to sit through a course-dinner on an ocean steamer.

[Illustration: HAYDEN VALLEY.]

[Illustration: APPROACHING THE MUD GEYSER.]

[Illustration: A STRANGER IN THE YELLOWSTONE.]

Not far from this perpetually active object is one that has been
motionless for ages,--a granite boulder enclosed by trees as by the
bars of a gigantic cage. It is a proof that glaciers once plowed
through this region, and it was, no doubt, brought hither in the
glacial period on a flood of ice, which, melting in this heated
basin, left its burden, a grim reminder of how worlds are made. Think
what a combination of terrific forces must have been at work here,
when the volcanoes were in full activity, and when the mass of ice
which then encased our northern world strove to enclose this
prison-house of fire within its glacial arms! One of our party
remarked that the covering of this seething, boiling area with ice
must have been the nearest approach to "hell's freezing over" that
our earth has ever seen.

Another striking feature of our National Park is its Petrified
Forest, where, scattered over a large area, are solitary columns,
which once were trunks of trees, but now are solid shafts of agate.
The substance of the wood, however, is still apparent, the bark, the
worm-holes, and even the rings of growth being distinctly visible;
but every fibre has been petrified by the mysterious substitution of
a mineral deposit. No doubt these trees were once submerged in a
strong mineral solution, tinted with every color of the rainbow.
Still, more marvelous to relate, an excavation on the hillside proves
that there are eleven layers of such forests, one above another,
divided by as many cushions of lava. Think of the ages represented
here, during which all these different forests grew, and were
successively turned to stone! This, therefore, is another
illustration of the conflict between Life and Death. Each was in turn
a victor, and rested on his laurels for unnumbered centuries.