nal framework to prove that comparatively long periods of
quiescence intervened between many distinct eruptions, during which the
cooling lavas ceased to flow, and became permanent additions to the bulk
of the growing mountain. With alternate haste and deliberation eruption
succeeded eruption till the old volcano surpassed even its present
sublime height.

[Illustration: MOUNT SHASTA, LOOKING SOUTHWEST.]

Standing on the icy top of this, the grandest of all the fire-mountains
of the Sierra, we can hardly fail to look forward to its next eruption.
Gardens, vineyards, homes have been planted confidingly on the flanks of
volcanoes which, after remaining steadfast for ages, have suddenly
blazed into violent action, and poured forth overwhelming floods of
fire. It is known that more than a thousand years of cool calm have
intervened between violent eruptions. Like gigantic geysers spouting
molten rock instead of water, volcanoes work and rest, and we have no
sure means of knowing whether they are dead when still, or only
sleeping.

Along the western base of the range a telling series of sedimentary
rocks containing the early history of the Sierra are now being studied.
But leaving for the present these first chapters, we see that only a
very short geological time ago, just before the coming on of that
winter of winters called the glacial period, a vast deluge of molten
rocks poured from many a chasm and crater on the flanks and summit of
the range, filling lake basins and river channels, and obliterating
nearly every existing feature on the northern portion. At length these
all-destroying floods ceased to flow. But while the great volcanic cones
built up along the axis still burned and smoked, the whole Sierra passed
under the domain of ice and snow. Then over the bald, featureless,
fire-blackened mountains, glaciers began to crawl, covering them from
the summits to the sea with a mantle of ice; and then with infinite
deliberation the work went on of sculpturing the range anew. These
mighty agents of erosion, halting never through unnumbered centuries,
crushed and ground the flinty lavas and granites beneath their crystal
folds, wasting and building until in the fullness of time the Sierra was
born again, brought to light nearly as we behold it today, with glaciers
and snow-crushed pines at the top of the range, wheat-fields and
orange-groves at the foot of it.

This change from icy darkness and death to life and beauty