luxuriant growth of Sequoia forests_. Indeed, all
my observations tend to show that in a prolonged drought the Sugar Pines
and firs would perish before the Sequoia, not alone because of the
greater longevity of individual trees, but because the species can
endure more drought, and make the most of whatever moisture falls.

Again, if the restriction and irregular distribution of the species be
interpreted as a result of the desiccation of the range, then instead of
increasing as it does in individuals toward the south where the rainfall
is less, it should diminish.

If, then, the peculiar distribution of Sequoia has not been governed by
superior conditions of soil as to fertility or moisture, by what has it
been governed?

In the course of my studies I observed that the northern groves, the
only ones I was at first acquainted with, were located on just those
portions of the general forest soil-belt that were first laid bare
toward the close of the glacial period when the ice-sheet began to break
up into individual glaciers. And while searching the wide basin of the
San Joaquin, and trying to account for the absence of Sequoia where
every condition seemed favorable for its growth, it occured to me that
this remarkable gap in the Sequoia belt is located exactly in the basin
of the vast ancient _mer de glace_ of the San Joaquin and King's
River basins, which poured its frozen floods to the plain, fed by the
snows that fell on more than fifty miles of the summit. I then perceived
that the next great gap in the belt to the northward, forty miles wide,
extending between the Calaveras and Tuolumne groves, occurs in the basin
of the great ancient _mer de glace_ of the Tuolumne and Stanislaus
basins, and that the smaller gap between the Merced and Mariposa groves
occurs in the basin of the smaller glacier of the Merced. _The wider
the ancient glacier, the wider the corresponding gap in the Sequoia
belt_.

Finally, pursuing my investigations across the basins of the Kaweah and
Tule, I discovered that the Sequoia belt attained its greatest
development just where, owing to the topographical peculiarities of the
region, the ground had been most perfectly protected from the main
ice-rivers that continued to pour past from the summit fountains long
after the smaller local glaciers had been melted.

Taking now a general view of the belt, beginning at the south, we see
that the majestic ancient glaciers were shed off right and left