way more rapidly than it travels; so
that although it is always advancing, it seems in reality to be
retreating.

Within the memory of the last three generations the Muir glacier filled
the bay for miles below our anchorage; and while it recedes, it is
creeping slowly down, scalping the mountains, grinding all the sharp
edges into powder or leaving a polished surface behind it. It gathers
rock dust and the wreck of every living thing, and mixes them up with
snow and ice. These congeal again, or are compressed into soft, filthy
monumental masses, waiting their turn to topple into the waves at last.
The wash of the sea undermines the glacier; the sharp sunbeams blast it.
It is forever sinking, settling, crushing in upon itself and splitting
from end to end, with fearful and prolonged intestinal reverberations,
that remind one of battle thunders and murder and sudden death. There
was hardly a moment during the day free from rumble or a crash or a
splash.

The front elevation might almost be compared to Niagara Falls in winter;
but here is a spectacular effect not often visible at Niagara. At
intervals huge fragments of the ice cliffs fall, carrying with them
torrents of snow and slush. Heaven only knows know many hundred thousand
tons of this _debris_ plunged into the sea under our very eyes. Nor was
it all _debris_: there were masses of solid ice so lustrous they looked
like gigantic emeralds or sapphires, and these were fifty or even a
hundred times the size of our ship. When they fell they seemed to
descend with the utmost deliberation; for they fell a much greater
distance than we could realize, as their bulk was beyond conception, so
that a fall of two hundred or three hundred feet seemed not a tenth part
of that distance.

With this deliberate descent, as if they floated down, they also gave an
impression of vast weight and when they struck the sea, the foam flew
two-thirds of the way up the cliff--a fountain three hundred feet in
height and of monstrous volume. Then after a long time--a very long time
it seemed to us--the ice would rise slowly from the deep and climb the
face of the cliff as if it were about to take its old place again; but
it sank and rose, until it had found its level, when it joined the long
procession drifting southward to warmer waves and dissolution.

In the meantime the ground swell that followed each submersion
resembled a tidal wave as it rolled down upon us and threatened to
engulf us