Through the eyes of the geologist one may look upon his native hills
and see them as they were incalculable ages ago, and as they
probably will be incalculable ages ahead; those hills, so unchanging
during his lifetime, and during a thousand lifetimes, he may see as
flitting as the cloud shadows upon the landscape. Out of the dark
abyss of geologic time there come stalking the ghosts of lost
mountains and lost hills and valleys and plains, or lost rivers and
lakes, yea, of lost continents; we see a procession of the phantoms
of strange and monstrous beasts, many of them colossal in size and
fearful in form, and among the minor forms of this fearful troop of
spectres we see the ones that carried safely forward, through the
vicissitudes of those ages, the precious impulse that was to
eventuate in the human race.

Only the geologist knows the part played by erosion in shaping the
earth's surface as we see it. He sees, I repeat, the phantoms of
vanished hills and mountains all about us. He sees their shadow
forms wherever he looks. He follows out the lines of the flexed or
folded strata where they come to the surface, and thus sketches in
the air the elevation that has disappeared. In some places he finds
that the valleys have become hills and the hills have become
valleys, or that the anticlines and synclines, as he calls them,
have changed places--as a result of the unequal hardness of the
rocks. Over all the older parts of the country the original features
have been so changed by erosion that, could they be suddenly
restored, one would be lost on his home farm. The rocks have melted
into soil, as the snow-banks in spring melt into water. The rocks
that remain are like fragments of snow or ice that have so far
withstood the weather. Geologists tell us that the great Appalachian
chain has been in the course of the ages reduced almost to a base