USA > California > History of California, Volume V > Part 3
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About the close of the Pliocene, and in early Quater- nary, the elevation of the west coast continued, causing deep cañons to be excavated by the vigorous streams, in the Sierra Nevada, and in the Coast ranges. This epoch has been called by Professor Le Conte the Sierran epoch. The results of this erosion are still seen in the deep cañons, the most striking scenic features of the Sierra Nevada, but those of the Coast ranges are now seen only on hydrographic charts, for they are now buried two or three thousand feet under the ocean. This shows that in early Quater- nary time the coast stood two or three thousand feet higher than now. The record of that time is purely one of events, for the sediments that were laid down in the bordering sea are now covered by the ocean, and the region that is now above sea-level stood too
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HISTORY OF CALIFORNIA
high for much deposition. The Sierran epoch cor- responds to the pre-Glacial or Ozarkian epoch of the eastern states.
Increasing cold accompanied the period of elevation, and this culminated in the Glacial epoch, in which the Sierra Nevada was covered by a continuous sheet of ice. The ice made its way down sheltering cañons to places that are now 3,500 feet above sea-level, but which then stood several thousand feet higher. This means that in the Glacial epoch the climate of Cali- fornia was very similar to that which now prevails on the Olympic peninsula in Washington, for in that region glaciers still come down to 6,000 feet above the sea, the climate is cool and rainy, and the forests consist almost entirely of conifers.
During the period of elevation the Channel Islands off the coast of southern California were connected with the mainland, allowing mammoths to make their way across on dry land. The channel was then a gulf, not unlike the present Gulf of California, and has been called the Santa Barbara gulf.
After the Glacial epoch had passed, there came another era of subsidence, but this time on a small scale, affecting only the immediate shore-line, which stood for a time from three to seven hundred feet lower than now. During this period were accumulated the marine San Pedro beds, known chiefly in the Santa Barbara gulf. At first the water was a little colder than at present, allowing marine life now characteristic of Puget sound to flourish as far south as San Pedro. Then it became warmer, and, for a short time, species that today cannot live north of Lower California made
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OUTLINE OF GEOLOGY
the Santa Barbara gulf their home. This history is remarkably like that of New England, where a warm Champlain epoch of depression followed the Ice Age.
After the San Pedro epoch there came on the west coast a renewed elevation, causing the streams to terrace the alluvial deposits that had filled the lowered valleys in the preceding epoch. This, too, has its counterpart in the Terrace epoch of New England. This time has left us no marine record, but only terraces on the streams, and along the shore.
The last phase in the physical history of the west coast is the recent subsidence 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 almost into modern time, 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 is remarkable and little appreciated that the physical history of the Pacific coast should be so like that of the eastern coast of America. On both sides we have the pre-Glacial, Sierran or Ozarkian, elevation of the land, and erosion of deep cañons; the southward advance of the glaciers; the Champlain, or San Pedro, subsidence and amelioration of the climate; the Terrace elevation and moderate erosion; and the recent sub- sidence that made the fiords of New England and of Puget sound, the gentler bays of California and Oregon on the west, and the sounds of the Atlantic states on the east. On both sides of the continent submerged
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HISTORY OF CALIFORNIA
cañons run out to sea, marking the course of drowned rivers of early Quaternary time, now forming channels of navigation, making possible the maritime commercial centers of the east and the west.
SYNOPSIS OF QUATERNARY HISTORY OF CALIFORNIA
RECENT
Subsidence epoch of Golden Gate and other bays
Invasion of Golden Gate River System by tide water and for- mation of the harbors of the west coast. This subsidence has been going on until very recent time, for Indian shell mounds around the Bay of San Francisco are partly flooded.
Terrace epoch
Terrace
Period of uplift and scouring out the channels filled during the San Pedro epoch, forming terraces in the fluviatile sediments of San Benito valley, and nearly all the valleys of the Coast range. The youngest (lowest) terraces of the San Pedro truncate the upper San Pedro beds and are later than they. The older (high- er) wave-cut terraces of the west coast probably date back to the Sierran epoch.
QUATERNARY
Upper San Pedro
Lower San Pedro
Champlain
Epoch of depression along the coast Coast stood 300-700 ft. lower than now
Warm wa- ter ma- rine fauna
Cold water marine fauna
Epoch of filling pre-existing val- leys with gravels and other fluvia- tile sediments. Seen in the Salinas valley, Santa Clara valley, San Benito valley, and the great valley.
Sierran epoch. Prob-
rest of the Quaternary ably longer than all the
Glacial
Period of elevation of the west coast, forming the great canons off the Sierras and the submerged canons of the coast. A period of no marine sediments (now ex- posed). In part contemporaneous with the Glacial epoch, for the glaciers of the Sierra Nevada came down some of the cañons.
The principal ter- racing along the coast took place at this time, and also the Channel Islands were connected with the mainland, as shown by the Santa Rosa Mammoth.
Pre-Glacial
The west coast then stood about 3,000 ft. higher than now, as shown by the submerged Monterey Bay cañon at a depth of 3,000 ft.
PLIOCENE
Merced Beds
Period of depression and filling of troughs with marine Plio- cene sediments, and formation of great Pliocene lakes above sea-level.
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OUTLINE OF GEOLOGY
ANCIENT CLIMATES OF CALIFORNIA
It may be thought that I am trespassing upon the province of the Weather Bureau, but, in fact, the ancient climatology of California belongs to the field of geology. There is preserved in the geologic record a climatic record going back untold millions of years, telling us of a time when the climate of California really was what we now claim it to be, when all the stories we tell our eastern friends would be true.
Mesozoic Climates of the West Coast. Since corals are wholly unknown in the Lower Triassic, and since the flora of that epoch is as yet little known, it is not possible to determine the temperature of either the land or the water. It is, however, certain that the oceanic temperature in India, in western America and in northern Siberia, was the same, for there is a re- markable similarity of the cephalopod faunas in all three regions.
It is also known that in the Permian and the Lower Triassic a dry climate prevailed over large areas, for products of desiccation, such as gypsum and saline deposits are common in many parts of the world, and even in regions that are now rainy, as in western Europe.
In the Upper Triassic there are great limestone masses and coral reefs in the Alps, the Himalayas and in California, with many species common to the three regions. Certainly the epoch of the Tropites subbullatus fauna was tropical up as far as Shasta county, Cali- fornia, for there reefs of Astræidæ are extensive. We may even be justified in assuming that the isotherm
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HISTORY OF CALIFORNIA
of 74° F. extended that far north. Indeed it probably extended up to southern Alaska, for the same coral reef fauna is found there in the Upper Triassic beds.
After the formation of the coral reefs in northern California and Oregon the facies changed suddenly from limestones to clay shales, and with this came an abrupt change in the marine fauna. The Indian types of cephalopods disappeared entirely, and in their stead came in a fauna of which the home seems to have been the Boreal region. Pseudomonotis ochotica was the commonest species in this fauna, and was widely distributed around the North Pacific. It has also been found as far south as Peru, on one side, and down to the equatorial part of the Indian ocean on the other. This wide dispersion does not necessarily mean a lowering of the oceanic temperature during this epoch, for this species may have lived in deep water, and therefore could easily find uniform temperature from the equator to the Arctic region. But the sudden change of facies and impoverishment of the fauna over such an enormous area are suggestive. A slight drop in temperature below 68º F. would account for it.
The last epoch of the Triassic, the Rhætic, has no marine faunas anywhere in America, but the flora, with its abundant cycads, is widely distributed in both the northern and the southern hemisphere. Coal deposits are common in this epoch, and this points to a very uniform and mild climate far beyond the present temperate zones.
At the opening of the Jurassic period we find a Mediterranean marine fauna established in western America; this same fauna also extended from the
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OUTLINE OF GEOLOGY
equatorial regions to Alaska, so that we are without evidence as to climatic zones, and can only infer that the temperature was uniform.
In the Middle Jurassic reef-building corals lived in the waters of the Great Basin sea, and their remains are quite common in Plumas county, California, but in that province they formed no reefs, for the waters were not clear, and much disturbed by the deposition of volcanic ash. Abundant cycads, a tropical group of palm-like plants, lived on the land in California at this time, adding their testimony to the warmth of the climate. This same Middle Jurassic marine fauna extended up to Queen Charlotte islands, and to south- ern Alaska, in the latter place with cycads interbedded with the salt-water fossils. Here, as was often the case, the cycads extended some distance north of the corals, a coral reef with Astræidæ being known in this epoch on Queen Charotte islands, in 53º N. lat., while cycads occur as far north as 57º N. lat. In this same epoch the northern limit for coral reefs in the Atlantic region was 53º N., in southern England, while the other invertebrates and cycads ranged up to 80° N. lat. A mild climate must have extended up nearly to the pole.
The Upper Jurassic of California shows a sharp contrast to the preceding epoch; its marine fauna is scanty, and what little there is belongs to the Boreal type, the Aucella fauna, which is characteristic of Russia, northern Siberia and Alaska. For a short time this fauna ranged down into the edge of the tropics in Mexico. This does not mean that the climate was cold, but merely that the temperature was lower than
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HISTORY OF CALIFORNIA
that at which reef-building corals and the other sensi- tive invertebrates could flourish. In the Lower Cre- taceous we find the same Boreal type still persisting as far south as middle California. But here, as in the Upper Jurassic, the evidence is conflicting, for cycads are known in both formations.
In the Lower Cretaceous epoch there was a sharp contrast between conditions on the Pacific and those on the Atlantic side of America. In the Atlantic waters coral reefs extended as far north as Texas, while no corals at all are known in the Pacific waters of America in California. In the Upper Cretaceous, on the other hand, coral reefs extended to Ensenada, Lower California, lat. 31° 30' N., while in the Atlantic waters they did not reach so far north. In other words, the Pacific waters on the western side of America became warmer in Upper Cretaceous time than they were in the preceding epoch, while in the Atlantic the conditions were reversed, as was the case also in southern Europe, where coral reefs extended much further north in the Lower Cretaceous than they did in the Upper Cretaceous.
The change in faunal geography in western America about the middle of the Cretaceous period is very remarkable. The Knoxville epoch had a Boreal fauna, while with the opening of the Horsetown epoch the facies changed rather abruptly, and an Indian fauna came in. Swarms of ammonites of Indian type oc- cupied the shallow marginal sea, showing at least a great change in geographic connections, if not in climate. It has been suggested by the writer that the opening of the Bering sea passage during the Mari-
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OUTLINE OF GEOLOGY
posa epoch of the Upper Jurassic and the Knoxville epoch of the Lower Cretaceous would account satis- factorily for the change of facies and the lowering of the temperature at that time. The closing of this passage near the end of the Knoxville epoch explains the change of facies from the Boreal to the Indian type of fauna, and also the accompanying rise of oceanic temperature on the coasts of western America.
The favorable conditions, inaugurated in the middle of the Cretaceous, continued throughout the Chico epoch, during which coral reefs extended up to Ense- nada, Lower California, N. lat. 31° 30', and a warm climate prevailed even in Alaska. Reef-building corals extended up to the middle of California, but they formed no reefs, since there were no stretches of clear sheltered waters in which they could flourish.
Neozoic Climates of the West Coast. The Eocene climate of the west coast was nearly the same as that of the Upper Cretaceous. The marine deposits have numerous molluscan genera that are now confined to the tropics, and on the land palms abounded in Cali- fornia, Washington and Alaska. No reef-building corals of this age are yet known anywhere on the west coast, and it is probable that the marine temperature was slightly below that necessary for their existence in this region. The climate of the coast, from Cali- fornia to Alaska, was probably very much like that of the states bordering the Gulf of Mexico. There today many tropical molluscan genera are found in the waters, and on the marginal coastal plain there is a mixture of palms, deciduous trees and conifers. This is just what we find in the fossil Eocene flora of California
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HISTORY OF CALIFORNIA
and Puget sound; laurels, figs, sycamores, chestnuts, elms, liquidambar, oaks, palms and sequoias lived together. From this association we should infer that the climate of the west coast was no longer tropical, but subtropical, and very rainy.
The middle Tertiary faunas are very like the present in the association of genera, and the flora on the land agrees with this. The palms have disappeared, but laurels still occur. It is probable that the climate of the upper Mio- cene had about the same temperature as that of the present in California, but it had, apparently, a much greater rain fall, or one much more evenly distributed.
The Tertiary flora of the west coast was immensely richer than the present. No elm, liquidambar, nor true laurel lives wild on the west coast now, and many other types that flourished here are gone. The im- poverishment of the present tree flora of California, as compared with that of the Tertiary, has been ascribed to volcanic activity, but this is absurd. In the first place the great extinction of the old types took place in the lowering of temperature near the end of Eocene time, while the era of great lava outbursts on the west coast was after the middle of the Miocene. The climate continued to cool off in the Pliocene, as is shown by the northern types of mollusca that then ranged as far south as Los Angeles, and by the fresh- water lake deposits of middle California, which contain a fauna at present confined to the Klamath region of northern California and southern Oregon. The flora of the Pliocene in California is very scanty, composed largely of willows, alders and conifers, very much like that of the Olympic peninsula in Washington.
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OUTLINE OF GEOLOGY
The constantly decreasing temperature throughout the Tertiary is sufficient to account for the reduction of the flora. The tropical and finally the warm- temperate types were killed off locally, and such as were confined to this region were wholly extinguished. Some of the forms that lived in more favored regions to the south returned after the Glacial epoch. But most of the region to the south of California is not favorable to the extensive growth of forests, and many of the types have never returned to California, except when brought in by man.
In the early Quaternary there were extensive ice- sheets in the Sierra Nevada, and probably the climate of the sea-coast was cool. The glaciers came down the slopes to a line that is now about 3,500 feet above sea-level; it is thought, however, that California stood considerably higher than now, and that conditions here were more like those of the present on the Olympic peninsula.
After the Glacial epoch was past the climate became warmer, and many mollusca crept slowly up the coast, from the warm waters of Lower California. This southern type reached as far north as Santa Barbara in the upper San Pedro epoch of the Quaternary, during which time the sea probably had a temperature as warm as it now is on the shores of Lower California.
This warming up of the west coast was no mere local phenomenon, for the same thing occurred at the same time on the eastern coast of America, when a warm-water fauna ranged up to the Champlain dis- trict. And also in Europe the climate after the Glacial epoch was, for a little while, warmer than it is at
34
HISTORY OF CALIFORNIA
present. After the San Pedro epoch on the west coast, and the Champlain in the east the climatic conditions became approximately what they now are, although it may well be that the Terrace epoch had a larger rainfall than that of the present.
In the foregoing pages it will be noted that during all the known Paleozoic the west coast enjoyed a warm and probably tropical climate, with some sug- gestion of a northward march of the isotherms, reaching a culmination in the Upper Carboniferous. There is then some indication of a southward recession of the isotherms in the Permian, and a renewed northward advance in the Lower Triassic. This continued until the middle of the Jurassic, but the farthest north was never again reached in the Pacific waters.
In the Upper Jurassic and the Lower Cretaceous another considerable southward recession of the iso- therms is indicated, followed by a renewed northward advance in the middle of the Cretaceous. But this advance did not reach so far north as that of the Middle Jurassic. The Eocene epoch shows the temperature of the west coast nearly holding its own, but with a probable slight reduction. The Miocene climate had grown considerably cooler than that of the Eocene, and by the Pliocene it was already rather cold as far south as California. The early Quaternary climate was probably even colder than the Pliocene, for there we have the local ice-sheets in the high mountains of California. The post-Glacial amelioration of climate is as distinct here as it was in eastern America, and in Europe, and probably as short-lived. Middle and late Quaternary time was probably much longer than
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OUTLINE OF GEOLOGY
we have been accustomed to consider it, and there have doubtless been considerable fluctuations in our climate in that period, but we have as yet been unable to decipher these in the geologic record of the west coast.
1363786
SOME GENERAL FEATURES OF THE CALIFORNIAN FLORA
C ALIFORNIA extends from north to south through almost ten degrees of latitude, rep- resented on the Atlantic coast by the distance from Newport to Savannah, and in the interior of the continent from Chicago to Natchez. The cli- matic conditions between the northern and southern extremes of these eastern states bring about floras so different that they are always treated separately. The flora of California is generally considered an entity, though besides the same difference in latitude there is added a greater difference in humidity, the north having a very heavy rainfall and the south almost none; and there are even greater extremes in altitude from moun- tains more than fourteen thousand feet above the level of the sea, to valleys below its level.
From east to west the state is roughly divided into the maritime region; the coast mountains with hot, dry valleys separating the many ranges and peaks; the Sierra Nevada whose lofty summits are never free from snow; the great San Joaquin and Sacramento valleys; and lastly the deserts south and east of the Sierra Nevada which belong to similar regions in Nevada and Arizona. These different sections north and south across the state result in as many floras as there are peaks, ranges, valleys, or deserts, each with endemic species and peculiar features, yet all more or less typically Californian.
The botanist who comes to California from other parts of the United States has the happiness of behold- ing a new world of plants when he first sees the Cali- fornian flowers during the period of greatest luxuriance. Even those cosmopolitan tramps-the weeds-show
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HISTORY OF CALIFORNIA
many unfamiliar species which have been brought from southern Europe or even the western coast of South America during the days of Spanish dominion when the missionaries established agriculture and fostered com- merce. Among the native flowers so many strange genera occur, even some new families, and scarcely a single species identical with any found elsewhere.
Environment is most essential in determining the character of any flora, and the chief factors are humidity, which depends generally on situation, and altitude, and soil constituents. However, environment is not all, for there are deeply interesting problems not yet satisfac- torily solved which concern the origin. These bring the student to the study of the fossil floras of the past ages and to a broad comparative survey of the floras of the whole world. In order to really comprehend one flora, its relation to others must be considered. To illustrate: The occurrence of the California nutmeg tree (Torreya Californica) belonging to the yew family, is paralleled by another species in Florida and two in Japan and China, but none elsewhere. The tree mallow (Lavatera assurgentiflora) which is commonly planted around vegetable gardens as a wind break by the Italians of the San Francisco bay region is a native of the islands off the coast of southern California. There are three other species, one in each of the islands, San Benito and Guadalupe and one in the Coronado islands; but neither on the mainland of California nor elsewhere in North America is there another species indigenous. To find them we have to go to the Canary islands and the Mediterranean region. Sometimes geology fills in the gaps as illustrated most conspicuously by the sequoias
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CALIFORNIAN FLORA
or redwoods. Their fossils are found in many parts of the northern hemisphere indicating a former wide dis- tribution and many species as contrasted with the two species now living in California, peculiar to this state and restricted in range. Sequoia sempervirens does not grow far from the coast, being bounded by the limit of the sea fogs, while Sequoia gigantea is found in scattered groves through the Sierra Nevada only. All such species closely related in form but remotely separated in time or place, undoubtedly indicate wide-spread distribution in the remote past, with conditions becoming unfavor- able for continuance except in isolated regions. This may also explain endemic species found isolated and numbering comparatively few individuals. The most notable examples are the Santa Lucia fir (Abies bracteata) which is found in a few cañons in the Santa Lucia mountains in Monterey county; the weeping spruce (Picea Breweriana) restricted to the high moun- tains of Trinity and Siskiyou counties and the adjacent mountains of Oregon; the Torrey pine (Pinus Torreyana) found near San Diego and on the island of Santa Rosa; the Monterey cypress (Cupressus macrocarpa) indige- nous to the coast of Monterey bay, though now widely cultivated; the Monterey pine (Pinus radiata) with a range slightly more extended and having a variety on the island of Santa Rosa with only two needles in a sheath instead of the three of the typical form. Examples might be continued indefinitely; for wherever these isolated species occur they are accompanied by other species in different families also endemic. The species of manzanitas (Arctostaphylos) which grow in
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HISTORY OF CALIFORNIA
the vicinity of the Monterey cypress and pine are not found elsewhere, and probably a third of the flora of the Monterey bay region is endemic.
The division of the year in California into the wet and dry season gives rise to a preponderance of annuals during the period of most luxuriant vegetation, repre- senting a bewildering number of species varying from their relatives often by such minute points of difference as to show the process of evolution now going on. Many genera are apparently in a state of transition. Well defined species mean that the links have not sur- vived; intergrading forms are those links. One of the best examples of such a transitional genus is the Eschscholtzia or Californian poppy. Some botanists divide this into more than a hundred species and others consider all to be forms of one. The clovers, lupines, hosackias, in the pea family; castilleia, orthocarpus, and pentstemon in the figwort family are other transi- tional genera. Many of the genera that are typically Californian show a similar lack of definition and a simi- lar difference of opinion among botanists. The extrem- ists are popularly known on the one side as the splitters and on the other as the lumpers. Some system is necessary for convenience, names are essential if we are to deal with these forms in any way, but it can be readily understood that in placing limits where there are none, the personal equation is so strong that agreement seems impossible. These problems give added fascination to the study of the Californian flora. What fills the evolu- tionist with delight and satisfies his theories, bewilders the systematist, brings him to despair or keeps him for- ever interested trying to solve the riddle of creation.
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