great flanks and backs are covered with a deep soil that nourishes a
very even growth of beech, birch, and maple forests. Though so old,
their tranquillity never seems to have been disturbed; no
storm-and-stress period has left its mark upon them. Their strata
all lie horizontal just as they were laid down in the old seas, and
nothing but the slow gentle passage of the hand of time shows in
their contours. Mountains of peace and repose, hills and valleys
with the flowing lines of youth, coming down to us from the fore-
world of Palaeozoic time, yet only rounded and mellowed by the aeons
they have passed through. Old, oh, so old, but young with verdure
and limpid streams, and the pastoral spirit of to-day!

To the geologist most mountains are short-lived. When he finds great
sturdy ranges, like the Alps, the Andes, the Himalayas, he knows
they are young,--mere boys. When they get old, they will be cut
down, and their pride and glory gone. A few more of these geologic
years and they will be reduced to a peneplain,--only their stumps
left. This seems to hold truer of mountains that are wrinkles in the
earth's crust--squeezed up and crumpled stratified rock, such as
most of the great mountain-systems are--than of mountains of
erosion like the Catskills, or of upheaval like the Adirondacks. The
crushed and folded and dislocated strata are laid open to the
weather as the horizontal strata, and as the upheaved masses of
Archaean rock are not. Moreover, strata of unequal hardness are
exposed, and this condition favors rapid erosion.

In imagination the geologist is present at the birth of whole
mountain-ranges. He sees them gestating in the womb of their mother,
the sea. Where our great Appalachian range now stands, he sees, in
the great interior sea of Palaeozoic time, what he calls a