h
the rising ground, keeping on the surface like water-plants rising on
the swell of waves. But at length the elevation of the meadow-land goes
on so far as to produce too dry a soil for the specific meadow-plants,
when, of course, they have to give up their places to others fitted for
the new conditions. The most characteristic of the newcomers at this
elevation above the sea are principally sun-loving gilias, eriogonae,
and compositae, and finally forest-trees. Henceforward the obscuring
changes are so manifold that the original lake-meadow can be unveiled
and seen only by the geologist.

Generally speaking, glacier lakes vanish more slowly than the meadows
that succeed them, because, unless very shallow, a greater quantity of
material is required to fill up their basins and obliterate them than is
required to render the surface of the meadow too high and dry for meadow
vegetation. Furthermore, owing to the weathering to which the adjacent
rocks are subjected, material of the finer sort, susceptible of
transportation by rains and ordinary floods, is more abundant during the
meadow period than during the lake period. Yet doubtless many a fine
meadow favorably situated exists in almost prime beauty for thousands of
years, the process of extinction being exceedingly slow, as we reckon
time. This is especially the case with meadows circumstanced like the
one we have described--embosomed in deep woods, with the ground rising
gently away from it all around, the network of tree-roots in which all
the ground is clasped preventing any rapid torrential washing. But, in
exceptional cases, beautiful lawns formed with great deliberation are
overwhelmed and obliterated at once by the action of land-slips,
earthquake avalanches, or extraordinary floods, just as lakes are.

In those glacier meadows that take the places of shallow lakes which
have been fed by feeble streams, glacier mud and fine vegetable humus
enter largely into the composition of the soil; and on account of the
shallowness of this soil, and the seamless, water-tight, undrained
condition of the rock-basins, they are usually wet, and therefore
occupied by tall grasses and sedges, whose coarse appearance offers a
striking contrast to that of the delicate lawn-making kind described
above. These shallow-soiled meadows are oftentimes still further
roughened and diversified by partially buried moraines and swelling
bosses of the bed-rock, which, with the trees and shrubs