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California: An Intimate History

1915; Taylor & Francis; Volume: 47; Issue: 7 Linguagem: Inglês

10.2307/201440

1931-0838

William Churchill, Gertrude Franklin Horn Atherton,

Asian American and Pacific Histories

Glacial erosion is the popular belief to-day, but to one brought up in an earthquake country the old theory seems more natural.CALIFORNIA tative writers on the disturbance of 1906, has this to say in Science, September 10, 1909: "The last phase of the physical history of the western coast is the recent sub- sidence that allowed the sea to encroach on the river- valleys forming the Bay of San Francisco and other bays along the coast.This has been going on in almost modern times, for Indian shell-mounds, apparently made by the same race that still exists in California, have been flooded by the continued subsidence of the Bay of San Francisco."It must be borne in mind that a geologist's modem time is not ours; but, as there is no evidence that Indians were living in California during any of the interglacial periods, nor, in all likelihood, for many years after the end of the Pleistocene-some twenty-five thousand years ago-we may believe, if we like, that the Bay of San Francisco is post-Drakian.Far more sharply outlined and more independent of its Indian traditions is the history of the Salton Sea.There is no doubt that when Francisco de Ulloa explored the Gulf of California in 1539 that long arm of the sea differed little if any from its present channel and termination.Its lost two hundred miles, to be known by us as Salton Sink, had run their course from a dismembered part of the Great Pacific Ocean, down through long geological ages to a mere desert of salt.The enemy here was the Colorado River, whose mouth was then some sixty miles east of its present location.It built, with true geological leisure, the delta that gradually separated the headwaters of the gulf from its main supply.This creature of a sovereign and cruel river was alternately toyed with and neglected ; sometimes rejuvenated with an abundant stream of fresh -water, '^' r^4 m THE GEOLOGICAL DRAMA or Golden Gate series.The boldest of the peninsula's headlands, Telegraph Hill, and the present islands in the bay are of sandstone interspersed with shales and rocks of peculiar interest to the geologist, not only for their age and record, but for their coats of many colors.In late Jurassic or early Cretaceous times, some twenty million years after its first baffled attempt to live, the coast, including what are now its bay shores and islands, then but a part of the range, was bom again.Folded and faulted on the sea's uneasy floor, the mass was pushed up into the light at last and permitted to grow and breathe, and harden and erode, and signal across a gray cold sea to the stately first-born of the west-for nearly a million years.Then down she went once more, and the Pacific stood on end and rushed with tidal ferocity at the in- vincible Sierra.But the Coast Range, if her ambitions were curtailed, did not waste her time.During that long period of sub- mergence she accumulated those deposits of fossiliferous, Cretaceous, Eocene, and Miocene treasures, so beloved of her students to-day.The sediments of the last period alone attained a thickness of eight thousand feet.This took time, and it was not until some twelve million years after her first appearance, and during the Miocene, that she got her hydra-headed masses out again.The faulting CALIFORNIA brief.In late Pliocene the Coast Range subsided once more, and only a long low chain of hills held their heads obstinately above the sea and broke the ponderous at- tacks of the Sierra's old enemy.It was during the Pliocene, late Tertiary, about six hun- dred thousand years ago, that the Coast Range achieved her wonderful series of deposits known as the Merced, which may be seen to-day along the edge of the ocean near San Francisco.The deposit is a mile in thickness, and at its base is what the sea has left of an old pine forest.During the last submergence it went down some five thousand feet, and so rapidly that the trees were buried under sediment before they could decay.In the upper beds are fossils of Recent Quartenary, which began (to be conservative) but twenty-five thousand years ago.Their elevation has been more gradual than their descent, and they are now tilted up at an almost perpendicular angle and dislocated by a fault.It was not long before that doughty coast proved what all geologists now admit-that her disposition, un- daunted by cruel vicissitudes, is to grow, and not long after her subsidence she began once more to rise.At one time, indeed (early Quartenary), she stood some three thousand feet higher than now, if we read aright the tale of her submerged cafions, eroded by other elements than the sea.But although she was forced to accept a later subsidence-no doubt to fill a hole in ocean's floor-she kept her heads out, as we have seen, and she has been growing ever since.It was at the beginning of the Miocene that certain faulting and folding developed the great earthquake rift of California.That was something over two million 8 THE GEOLOGICAL DRAMA years ago, and one shudders to think what it must have done in its heyday.For that old wound has never healed ; every forty or fifty years the Coast Range has an acute attack of Miocene fever, accompanied by spasms and followed by many minor protests at this long chastise- ment of nature.But these are merely the pangs of old age, which she endures with more equanimity than we do, nmiinating as she must upon the visitations of her youth and maturity; and not only upon those painful births, deaths, burials, and reincarnations, but that terrific vulcanic period when she was forced to tear apart her smooth young flanks and the most lofty and aspiring of her brows to disgorge into the shrinking central sea the molten masses the earth could no longer contain.That, of course, was the most spectacular era of our Western Hemisphere's history, but the great Sierra herself was too fully occupied letting the fiery blood of the swollen patient to observe and admire the new activities of her interesting neighbor.But to the men in the moon, whose atmosphere as it sank inward may have been converted, for aught we know (all things being so wonderful at that time), into a powerful lens, it must have been a stupendous drama : that red and roaring world, dulling the music of the spheres, ten hundred thousand thousand flames distorted into as many shapes, and seen fitfully through a smoky curtain rent with boiling rock magma.The igneous activities began with the close of the Cretaceous period and reached its climax some seven million years later in the Miocene, although by no means its end.Of course, the Coast Range, being swallowed periodically, was unable to discharge her share of the 9 CALIFORNIA obligation during all of that time, but making due al- lowance for periods of rest-throughout long geologic ages-and these mean tens of thousands of years at best torrents of flaming lava poured incessantly from the lofty craters and the mangled sides of both of California's mountain-chains.Before the waters retreated during the early Pliocene the central sea was a steaming hissing cauldron, hiding the throes of one range from the other, and after that the valley was dry and scorched, the thick Miocene deposits pelted with red-hot rocks and ash.Gradually, however, the valley floor was raised and built up by sediment, and during those intervals, now and then, when the plutonic energy of the mountains ceased, the ranges, scarred and battered but serene, smiled at each other across a magnificent valley, dotted with lakes and groves of trees, and, no doubt, ancient and fearsome monsters, now happily extinct save in museums.And during all these measureless eons, while her neighbor was tossed aloft or recalled to stop a hole in the sea, the Sierra had many and varied trials of her own, holding her breath for centuries, wondering if she, too, were to be engulfed, if that persistent, ponderous, roaring ocean meant to devour her.There had been compression and faulting at the end of the Palaeozoic, as well as some igneous activity and, later, erosion.The whole range, about eleven million years ago, at the close of the Jurassic, was once more compressed, folded, and then triumphantly uplifted.But the elements peneplained her until the close of the Miocene, and the sea tore at her roots unceasingly, although never again to dislodge them.Rivers wore away her surfaces, to lay the floor of the central sea until she was some four thousand feet lower than she is lO THE GEOLOGICAL DRAMA to-day.It was during this period, when the vast Eocene sea threatened her existence, and she was torpid with fear and exhaustion, that her "aged rivers" rescued the gold from her battered veins and, crawHng downward with their heavy burden, disgorged it into the lower canons, or carried it out into the sea between the ranges, where it sank into the rising beds of future rivers.In the late Miocene, or early Pliocene, the central waters receded for ever, and the Sierra, during a long and blessed interval between igneous violence, was elevated again, and her streams, like herself, rejuvenated.During these intervals of repose she no doubt was almost as beautiful as she is to-day; although the caiions and scenery of the highest portions of the range are post- Tertiary, the work of the ice-chisels, her vigorous streams carved deep canons into her lower slopes, quite as fine as those cut into the lost pedestal of the Coast Range.Then once more her great chimneys sent forth their pillars of flame and smoke and were answered by the watch-fires on the heights opposite, and the valley was pounded with rock and covered with lava and dust and the bones of monsters, for which there was no escape.To this long age of alternate turmoil and the heavy fatigue of convalescence, or the brief periods of rejuvenation and beauty, succeeded an epoch of terrible repose.After the trial by fire the punishment of the ice.Although California was too far south to be included in the great ice-sheet that came down out of the north in the Pleistocene (glacial) era she had an ice age of her own which, with the interglacial periods, lasted some five hundred thousand years.During the greater part of this time the Sierra was II CALIFORNIA covered with a continuous sheet of ice.The crystal masses were packed into every canon and river and lake, covered every crag and table-land, rose in frozen waves from the dead craters of a thousand volcanoes.The ice laid its heavy weight on the harsh outlines of the mountains, mighty hands grasping a million little chisels to carve the high canons, the pinnacles and domes and turrets, the arches and lacework and spires, that make the Sierra Nevada a thing of wonder to-day.It was the turn of the Coast Range, less afflicted, to watch and admire and hold its breath in the face of that stupendous beauty which only death could create.For silent interminable centuries the crystal mountains flashed prismatically in the sunlight or lay white and cold under the gray mists that rose from the frozen earth.Then came the first long interglacial period, when the ice- sheets crept down the mountainsides, carrying great masses of decayed material to choke the Central Valley, whose lakes and rivers, released from the long and bitter winter, sparkled in a warmth and sunshine almost forgotten.The rocks breathed again and called to the green hills of the coast, protected by the milder currents of the Pacific, from the assault of the ice, but only for a brief space of fifty to a hundred thousand years.Like the Coast Range, during her earlier trials, the Sierra was engulfed again, not by a vast and restless sea, but equally helpless under snow-fields and ice-sheets.But all things come to an end, temporarily at least.The Coast Range witnessed the last of the interglacial periods, the last of the ice descents which is behind us; life struggled from below the soil ; the mountainsides and '-"i r .:^^lllbrj|.9 ^-i^L ^^^^^^i ' ^^^^^^^^m t •^V i' X:',-^H^^Mik-v.,^^^L' '•'.'.