yers of snow render the bridging-masses dense and
firm, so that one may safely walk across the streams, or even lead a
horse across them without danger of falling through. In June the
thinnest parts of the winter ceiling, and those most exposed to
sunshine, begin to give way, forming dark, rugged-edged, pit-like sinks,
at the bottom of which the rushing water may be seen. At the end of June
only here and there may the mountaineer find a secure snow-bridge. The
most lasting of the winter bridges, thawing from below as well as from
above, because of warm currents of air passing through the tunnels, are
strikingly arched and sculptured; and by the occasional freezing of the
oozing, dripping water of the ceiling they become brightly and
picturesquely icy. In some of the reaches, where there is a free margin,
we may walk through them. Small skylights appearing here and there,
these tunnels are not very dark. The roaring river fills all the arching
way with impressively loud reverberating music, which is sweetened at
times by the ouzel, a bird that is not afraid to go wherever a stream
may go, and to sing wherever a stream sings.

All the small alpine pools and lakelets are in like manner obliterated
from the winter landscapes, either by being first frozen and then
covered by snow, or by being filled in by avalanches. The first
avalanche of the season shot into a lake basin may perhaps find the
surface frozen. Then there is a grand crashing of breaking ice and
dashing of waves mingled with the low, deep booming of the avalanche.
Detached masses of the invading snow, mixed with fragments of ice, drift
about in sludgy, island-like heaps, while the main body of it forms a
talus with its base wholly or in part resting on the bottom of the
basin, as controlled by its depth and the size of the avalanche. The
next avalanche, of course, encroaches still farther, and so on with each
in succession until the entire basin may be filled and its water sponged
up or displaced. This huge mass of sludge, more or less mixed with sand,
stones, and perhaps timber, is frozen to a considerable depth, and much
sun-heat is required to thaw it. Some of these unfortunate lakelets are
not clear of ice and snow until near the end of summer. Others are never
quite free, opening only on the side opposite the entrance of the
avalanches. Some show only a narrow crescent of water lying between the
shore and sheer bluffs of icy compacted snow, masses of which