inite; an instinct which, while it baffles
analysis, is sound, for there are few rocks of the earth's skin so aged
as these ornate shales and limestones.

And now, at last, you can imagine Glacier!

III

But, with Glacier, this is not enough. To see, to realize in full its
beauty, still leaves one puzzled. One of the peculiarities of the
landscape, due perhaps to its differences, is its insistence upon
explanation. How came this prehistoric plain so etched with cirques and
valleys as to leave standing only worm-like crests, knife-edged walls,
amphitheatres, and isolated peaks? The answer is the story of a romantic
episode in the absorbing history of America's making.

Somewhere between forty and six hundred million years ago, according to
the degree of conservatism controlling the geologist who does the
calculating, these lofty mountains were deposited in the shape of muddy
sediments on the bottom of shallow fresh-water lakes, whose waves left
many ripple marks upon the soft muds of its shores, fragments of which,
hardened now to shale, are frequently found by tourists. So ancient was
the period that these deposits lay next above the primal Archean rocks,
and marked, therefore, almost the beginning of accepted geological
history. Life was then so nearly at its beginnings that the forms which
Walcott found in the Siyeh limestone were not at first fully accepted as
organic.

Thereafter, during a time so long that none may even estimate it,
certainly for many millions of years, the history of the region leaves
traces of no extraordinary change. It sank possibly thousands of feet
beneath the fresh waters tributary to the sea which once swept from the
Gulf of Mexico to the Arctic, and accumulated there sediments which
to-day are scenic limestones and shales, and doubtless other sediments
above these which have wholly passed away. It may have alternated above
and below water-level many times, as our southwest has done.
Eventually, under earth-pressures concerning whose cause many theories
have lived and died, it rose to remain until our times.

Then, millions of years ago, but still recently as compared with the
whole vast lapse we are considering, came the changes which seem
dramatic to us as we look back upon them accomplished; but which came to
pass so slowly that no man, had man then lived, could have noticed a
single step of progress in the course of a long life. Under
earth-pressures the skin buckled and the Ro