Popular Science Monthly/Volume 82/February 1913/The Geologic History of China and its Influence Upon the Chinese People
|THE GEOLOGIC HISTORY OF CHINA AND ITS INFLUENCE UPON THE CHINESE PEOPLE|
UNIVERSITY OF WISCONSIN
THE Chinese empire includes an area larger than the United States with the addition of Alaska and our insular possessions. A large part of this vast area, however, is made up of dependencies which are but loosely joined to China proper, and are not essential to its integrity. She has lost and regained these dependencies from time to time in the past, and the same process may continue. The accompanying map will serve to show the relation of these component parts of the empire to each other and to surrounding countries.
Divested of its outlying possessions, China consists of eighteen
provinces, which may be compared in a general way to our states. The provinces are, however, generally larger than the states and on the whole much more populous. There is still greater dissimilarity in government because, whereas our states are representative democracies, the Chinese provinces were, at least until within a year or two, satrapies ruled absolutely by imperial governors or viceroys.
Not a few people in America picture China as a vast fertile plain, perhaps like the upper Mississippi valley, densely populated and intensively cultivated. In fact, however, it is so generally mountainous, that less than one tenth of its surface is even moderately flat. On the west, especially, it is ribbed with cordilleras from which its two great rivers, the Yang-tze-Kiang and the Huang-ho flow eastward to the Pacific.
In addition to this diversity of surface there is also much variety of climate. In the northwest the conditions are dry and severe like those of Montana and central Wyoming; while in the southeast they are humid and sub-tropical, approaching those of the Philippine Islands. Such are the extremes.It is a fact well known to geologists that continents, and therefore countries, have not always existed in their present state, but that they have been built as a result of successive events and changes of conditions. If we were to dig beneath the surface in any part of China, we should find first one stratum and then another, and we should see also that these strata have been bent, cracked and otherwise disturbed. Some of these structures are old and some young. It would be somewhat like excavating in an ancient city, where one house or temple has been built upon the ruins of its predecessor, and each affords a crude record of its time. The geologic structure of such a country as China has been determined
|Fig. 4. Low Isolated Mountain Group in Northeastern China.
Fig. 5. Two Farmers Raising Water from the Grand Canal into the Head of an Irrigating Ditch by means of a Wicker Basket slung between them.
|Fig. 6. A wide River Plain among the Mountains of Shan-tung. The bridge of stone slabs across the sand laden river is part of the principal wheel-barrow road of the valley.|
Fig. 7. A Typical City Wall, with Gate Tower.
largely by the rocks of which it consists, partly by the climate to which it has been subject, but chiefly by the geologic events which have occurred during its history. Of course the beginnings of that history are unknown, just as the human history of China shades into darkness when we attempt to trace it back into the remote ages. But the present features of the land are chiefly due to the later events in its life, and these have been partly worked out by the geologists who have explored its surface.
We may take as a convenient starting point for our interpretation a time far back in geologic chronology when China was a land surface which had been exposed to erosion so long that nearly all the hills and mountains that may have existed there before had been worn away, leaving a relatively flat plain with groups of low hills here and there. The rocks beneath this plain were of various kinds, most of them highly folded. Eventually this surface was submerged beneath a comparatively shallow inland sea, and although the uneasy movements of the earth's body caused the sea bottom to emerge occasionally, it remained below the water nearly all through the geologic periods which constitute the Paleozoic era. By the end of that time we may picture China as a shallow sea bottom rising very gradually to a marshy coastal plain on the east. During the long intervening ages the accumulation of sediments upon the sea bottom had formed successive layers of limestone, shale, and sandstone, which eventually reached a thickness of 5,000–10,000 feet.
This condition did not hold without end, for eventually strong compressive forces, engendered in the underlying body of the earth, squeezed the superficial rocks into folds, and thus bulged the surface high above sea level in the region so affected. By the prompt attack of streams, winds, glaciers, and the other agencies which are incessantly sculpturing the surface of the earth, these elevated districts were, even while rising, carved into rugged mountains and deep valleys, so that the original folds were greatly disfigured even before the compressive forces ceased to operate.
It is a fact generally recognized among geologists, that in terms of geologic time such episodes of compression and folding are short-lived. They are soon followed by much longer periods during which the internal forces of the earth are quiescent, but in which the erosive agencies have free play. If any land remains indefinitely above sea level, and is not disturbed by movements from below, the mountains and hills will eventually be worn away and there will be left only a broad almost featureless plain. It is believed that China, in consequence of such a period of quiescence, was reduced to a lowland from which almost all of the preexisting mountains had been removed. In this condition it probably remained for more than one geologic period, and the western part may even have been submerged beneath the sea which at that time
|Fig. 8. Heavily Loaded Freight Wheel-barrows with Mules for Motive Power.||Fig. 10. Freight Wheel-barrows rigged to take Advantage of a Favorable Wind.|
|Fig. 9. A Typical Passenger Cart.||Fig. 11. A Medium-sized Houseboat used on the Yang-tze-kiang and its Tributaries.|
covered northern India and part of Thibet. In that sea were deposited the thick beds of limestone which are now found in some of the western mountain ridges.
Again in the Miocene period, the forces of distortion within the earth accumulated to such strength that they were able to repeat the mashing and folding, but this time the area affected lay farther to the west and south. At the same time, or perhaps earlier, the eastern part of China was cracked in various directions; and the intervening blocks, settling somewhat unevenly upon their bases, left a group of escarpments and depressions comparable to those now to be found in western Nevada and southern Oregon. As before, the work of erosion and the leveling of the surface was at once accelerated, so that even before the deformation had spent itself the blocks were deeply scarred. It is uncertain how far this period of erosion succeeded in reducing China to base-level. The consummation may have been prevented by gentle warpings of the surface, rising very slowly here and sinking there. When compared with the great breadth of the areas affected, these changes of level seem very slight, but they are nevertheless sufficient to cause great changes in the aspect of the country.
It is one of the basal principles of physiography that streams tend to produce in their channels an almost uniform slope from their headwaters to the sea. If any part of the channel is so flat that the stream is too sluggish to carry sediment, it is built up until it reaches the required gradient; and on the other hand, if any part has too steep a declivity, it is gradually worn down to the proper slope. In consequence of this law, the parts of China which were slightly bulged above their original level were re-attacked by the branching systems of rivers with renewed vigor. By carving out the softer rocks, these have made deep valleys with intervening mountain ranges. Some of the larger rivers, such as the Yang-tze-kiang, maintained their courses in spite of the slow uplifts directly athwart their courses. A result is the magnificent series of gorges along the central Yang-tze where the great river has sawed its way through a slowly rising mass of hard complexly folded rocks.
On the other hand, the broad areas which were depressed not only below the general level of stream action, but below sea-level, were rapidly filled with sand, loam and clay washed down out of the adjacent mountains by the streams. The process of filling the depressions is the exact complement of the process of etching out the highlands. No doubt the rivers have been able in large measure to keep pace with the sinking movement of the ground, so that great rivers like the Huang-ho may have maintained perfectly graded courses across the region of depression from the mountains to the sea. While thus engaged in building up its channel, the river in time of flood frequently breaks through its low banks, shifts its channel, and then begins to fill up a
new and hitherto lower part of its surroundings. By the long continuance of this process of repeated shiftings and fillings, the great eastern plain of China and many smaller plains have been produced. It is here, where the population is densest and the rivers least confined, that the devastation by floods and their attendant famines is greatest.
By this succession of events the surface of China is believed to have reached its modern condition. We may now consider it piecemeal and see how the existing geologic conditions, which are the result of this long series of past changes, influence the habits, occupations and even mental traits of the people. Because space is limited and also because I have not seen all the physiographic divisions of China, it will not be possible for me, even briefly, to describe each of them. A few are therefore selected to show the range of variety of the whole.
|Fig. 14. Cave Houses in the Loess, faced with stone.||Fig. 16. A Pack Train of Donkeys, on the Imperial Highway over the Loess Plateau.|
|Fig. 15. Men and Donkeys carrying Coal from the Mines in Shansi.||Fig. 17. A Roadside Village and small Fields at the Bottom of the Mountain Valley.|
The mountains of northeastern China, typified by the province of Shantung, are unlike those of the rest of the country in several respects. Although the individual peaks are often sharp and rocky, they are generally separated by wide, flat-bottomed valleys. The process of erosion has here gone so far that the rivers have already carried away most of the land, leaving only isolated groups of low mountains. The broad valleys accommodate a relatively large number of people, who congregate in the villages dotting the intermontane plains. In contrast with most mountainous regions, travel between the different valleys is comparatively easy here, because many of the passes are but little higher than the plains themselves and constitute scarcely any obstacle to progress. Roads are plentiful, and so the cart and the wheel-barrow are the principal vehicles for through traffic.
This is one of the few parts of China where boats can be but little used. The streams are shallow and full of sand bars, and on account of the pronounced wet and dry seasons many of them are intermittent. For these reasons the majority of them are not navigable. The deeply eroded land of Shan-tung has, however, suffered a relatively recent
movement—apparently a sinking of the land—which has allowed the ocean to penetrate the mouths of many of the coastal valleys. This marginal drowning has produced some excellent harbors—such as that of Chee-fu, the great silk port, and Tsing-tau, the German stronghold. On the west, and encircling the Shantung hills, lies the great plain of the Huang-ho or Yellow River, which will serve as the type of many much smaller plains in various parts of China. As explained before, this vast gently sloping plain has been built by the Yellow River and some of its tributaries in an effort to preserve a uniform gradient across
|Fig. 19. A two-man Wheel-barrow carrying a merchant and his stock of Goods.||Fig. 23. Irrigating with Water pumped from a well.|
|Fig. 20. A River Junk.||Fig. 24. A Sedan Chair swung between two Mules.|
|Fig. 21. A Friendly Crowd in an Inland Town.||Fig. 25. Getting his Initiation into Farming, with Grub-hook and Basket.|
|Fig. 22. Mongolian Camels in Northwestern China.||Fig. 26. Coolies Fording a Mountain River.|
the sunken portion of eastern China. Like the lower Mississippi and all other rivers which are building up rather than cutting down their beds, the Huang-ho is subject to frequent floods and occasional sniffings of its channel. Its course between the mountains and the sea has thus been changed more than fifteen times in the last 3,000 years. In these incessant shiftings, the river has strewn all over an enormous area, 500 miles from north to south by 300 miles from east to west, layer after layer of fine yellow loam or silt; the very name "Yellow River," which is a translation of the Chinese "Hwang-ho," suggests the close resemblance to our own mud-laden Missouri. Almost every square foot of this vast alluvial fan is of course underlain by a deep and fertile soil and is intensively cultivated by the industrious Chinese inhabitants. One sees no large fields of grain, such as those on our Dakota prairies, but instead, thousands of small truck gardens belonging to the inhabitants of the hundreds of little mud-walled villages with which the plain is dotted. The ever-present town walls have doubtless been built because the inhabitants have no natural refuges, as their mountain cousins have, and their very accessibility has made them in the past the frequent prey of Mongol and Tartar invaders, or of rebels and rioters from within their own country.
Since the water supply of the plain is not lavish, but little rice is grown there. The dry-land grains, and such vegetables as cabbages and potatoes, are the staple crops. The small gardens are sparingly irrigated, however, in times of drought, by water taken from the canals or wells with the help of various types of crude pumps, operated by men or by donkeys.
In this densely populated alluvial plain there is practically no pasturage and no woodland. From the very nature of the plain it could not yield coal, which is always associated with the solid rocks. To bring fuel, as we do, from distant parts of the country is impossibly expensive for the Chinese, without an adequate railroad system, and that is still a thing of the future. When the harvest has been gathered in the autumn, the village children are therefore sent out to gather up every scrap of straw or stubble that can be used either for fodder or for fuel. The fields thus left perfectly bare in the dry winter season afford an unlimited supply of fine dust to every wind that blows. This is doubtless the explanation of the disagreeable winter dust-storms with which every foreigner who has lived in northern China is only too familiar.
Although carts and wheel-barrows are much used on the Huang-ho plain, their traffic is chiefly local. That may be due in part to the fact that the numerous wide and shifty rivers are difficult to bridge, while ferrying is relatively expensive. Another, and perhaps more important, reason is that the rivers, and particularly their old abandoned courses, afford natural waterways which are available nearly everywhere. By taking advantage of these, or by deepening them, and in some places by actually digging canals through the soft material of the plain, the Chinese have put together the wonderful system of interlaced canals for which they have been renowned since Europeans first visited them.
The thousands of junks which ply these waterways maintain a volume of inland commerce, which is inferior only to that of the great railroad countries, such as the United States. The relative freedom of communication in this great plain of the Yellow River has helped to bring about a greater homogeneity in the people than in any other equally large part of China. Here we find a single dialect in use over the entire region, whereas in some parts of southern China the natives of even adjacent valleys speak languages almost unintelligible to each other. The other common effects of isolation, such as the lack of acquaintance with the customs of outside peoples, the hatred of foreigners, the peculiar local usages, and many other things, are less prominent here than in other parts of the empire. Excepting the coastal cities, there is no safer part of China for foreigners to travel through.
West and northwest of the Yellow River plain lie the more rugged plateaus and mountains of northwest China, with their sub-arid climate presaging the approach to the deserts of Mongolia. Over much of this region the ancient limestones and sandstones are still horizontal or are gently folded, with occasional dislocations along faults. On account of the comparatively recent uplift and differential warping which this part of China has suffered, the streams have been greatly accelerated in their work, so that they have hollowed out canyons in the raised portions and have filled in the depressed basins with sand and silt. This is the region celebrated among geologists on account of the loess, or yellow earth, which lines the basins and mantles the hillsides everywhere. It is believed that this is very largely a deposit of windblown dust, although it has been worked over considerably by the streams from time to time. No doubt Baron von Richthofen, the distinguished German explorer, was near the truth when he concluded more than forty years ago, that the "yellow earth" was the dust of the central Asian deserts carried into China by the northwest winds. The presence of the loess determines, in large measure, the mode of living adopted by the inhabitants. Because of its fertility and moisture-conserving properties, it is well adapted to dry farming, and there is little water for irrigation. The Chinese are not content with using the level bottom lands, but successfully cultivate the hillsides wherever a deposit of the loess remains. In order to prevent the soil from washing off from these steep slopes, they build a series of stone walls, thus forming soil reservoirs or terraces. In this way nearly all of the soil is utilized.
In such a country rivers are not numerous and those which exist have many rapids and shoals. Boats are therefore but little used in northwest China. For both passenger and freight traffic, pack animals or rude vehicles are the chief reliance. For passengers there are also the palanquin or sedan-chair and the mule-litter. Where the country is not too rough, the two-wheeled cart is the usual conveyance for merchandise.
Over the mountain passes, however, and in many of the smaller valleys, roads are so narrow that carts can not be used, and so here pack animals, particularly horses and mules, are substituted. The traveler in this part of China is often reminded of his proximity to Mongolia by the frequent sight of camels. They are nevertheless not indigenous beasts of burden and the inhabitants themselves do not use them.
In consequence of the swampy state which prevailed in this part of China far back in the Carboniferous period, thick deposits of coal were formed. These are now exposed in the deep valley slopes between beds of limestone and sandstone, and the circumstance has made Shansi province the principal coal-producing district of China. The coal is mined by very primitive methods and as there is still no adequate system of railroads in this or any other part of the empire, the product can be transported only in carts or on pack animals. Either of these modes of carriage is so expensive that it becomes unprofitable to transport the coal more than 60 to 100 miles from the mine, and so the denizens of a great part of northern China, where fuel is scarce and the winters are severe, are no more able to obtain it than as if the United States contained the only coal fields in the world. The advantages that will accrue from the building of railroads in northern China are many, but one of the greatest will be the wide distribution of this essential fuel.
In going, south by west from the plateau country, one enters a region of warmer climate and more generous rainfall, which, for want of a more distinctive name, I have called the Central Ranges. This is the part of China which was particularly affected by the rock-folding movements of the Jurassic period, and which in a much more recent time has been and therefore newly attacked by the streams and other erosive agencies. Broadly regarded, it is a complex of sharp mountain ridges and spurs with narrow intervening valleys. The ridges are not so high, however, but that they are clad with vegetation, and the scenery is therefore not alpine. The surface is nevertheless very rugged and its internal relief averages at least 3,000 feet. The roughest parts of our Carolinas resemble it in a measure. In such a region obviously, there is no room for a dense population. Wherever there is a little widening of the bottom of the valley, there is a farm or occasionally a small village; and even the scattered benches high up the mountain sides are reached by steep trails and diligently cultivated. But even when all of these are combined, the total area of land under settlement is relatively small.
In this region there are no railroads whatever, and although wagon roads could be built in some places, they would be expensive, and the Chinese have not yet attempted to make them. All travel and commerce,
therefore, depend on the agency of pack animals or coolies, and the roads they follow are mere trails winding around the steep mountain sides or threading the bottoms of narrow valleys, where swift streams must be forded at frequent intervals. Under such circumstances it is evident that there can be but little effective traffic. Only comparatively light and expensive articles can be transported long distances. Around the edges of the mountain mass where the populous cities of the adjoining plains can be reached with one or two days' travel, there has been for centuries an important trade in lumber. The mountains have now been so largely deforested, however, that it is necessary to go farther and farther back into the heads of the valleys to find large trees. Hence, only the more expensive kinds of lumber such as coffin boards—which are absolutely indispensable, even to the poorer classes,—can profitably be brought out. These are often carried for 20 or 30 miles on the backs of coolies—a costly mode of transportation. The smaller trees and brush the mountaineers convert into charcoal, which they carry on their own backs down to the towns along the foothills.
Lack of transportation facilities is doubtless the chief reason why the opium poppy has in the past been widely cultivated in this part of China, although the practise has lately been prohibited by the government. The advantage in poppy culture was that it could be carried on in small scattered fields and the product was so valuable for unit of weight that it would pay for long-distance transportation across the mountains. The inhabitants of the region themselves were not, however, generally addicted to the use of the drug.
The rainfall of the central mountain region is sufficient to supply the many springs and tributary brooks of which the people have made use in irrigation. The mildness of the climate here permits the growing of rice, and by terracing the hillsides they are able to make a succession of narrow curved basins in which the aquatic crop may be grown. For the cultivation of rice it is necessary that the fields be completely submerged during part of the season, and so there must be a plentiful supply of water.
On the larger rivers such as the Han and the Yang-tze, and their chief tributaries, boats are successfully used. In fact, the Chinese river boatmen are so skilful in the handling of their high-prowed skiffs, that they navigate canyons full of rapids which most of us would consider too dangerous to attempt. The descent of one of these rivers is an easy although exciting experience. The return trip, however, is slow and laborious, for the boats must be dragged upstream by coolies harnessed to a long bamboo rope, which has the advantage of being very light as well as strong. In the many places where the river banks are so precipitous that it is impossible to walk along them, it becomes necessary
for the boatmen to pole around the cliff or to zigzag from one side of the river to the other to take advantage of every foothold.
Through the central part of this mountain uplift, the great Yang-tze River, which in its lower course readily accommodates large oceangoing vessels, has carved a succession of superb gorges. In many places the gray limestone walls rise from 3,000 to 4,000 feet above the river, and the stream is compressed into less than a tenth of its usual width. Difficult and dangerous as are these canyons, beset with rapids and whirlpools, they afford the only ready means of communication between eastern China and the fertile basin of Sze-chuan, which lies west of the Central Ranges.
Without the highway of the Yang-tze, this great province, four times as large as Illinois and with more people than all of our states east of the Mississippi River, would be unable to export its many rich products or to enjoy the commerce of outside provinces and nations. It has been effectually barred off from India and Burma by the succession of high ranges and deep canyons which appear to be due primarily to the great epoch of folding in the Miocene period. Sze-chuan is a broad basin which has never been depressed low enough to force the streams to level its bottom with alluvial deposits, as in the Yellow River plain to the east; nor does it seem to have been elevated into a high plateau which would have been carved by many streams into a rugged mountain country. The soft red sandstone beds which underlie it have therefore been sculptured into a network of valleys with intervening red hills or buttes. With a climate as mild and moist as that of Alabama, and a diversified topography, there is opportunity for many industries, and for the cultivation of a great variety of crops. Sze-chuan leads all the provinces in the exportation of silk. Here grow the lacquer and oil nut trees and a wide range of field and garden fruits, grains and vegetables. Ample water for irrigation and especially for rice-culture is supplied by the many perennial streams which descend from the encircling mountains. These uplifted and now mountainous tracts have also served as a barrier to invaders from all directions, so that this has been less subject to wars than almost any other part of China, and hence has been more stable in development. Its inhabitants are among the most substantial and progressive components of the Chinese nation.
We now come to the last of the geologic divisions which were laid out for consideration. From the Sze-chuan basin southwest to the
Fig. 32. One of the great Limestone Gorges through which the Yang-tze-kiang pierces the Central Ranges.
confines of India there extends a series of high mountain ranges separated by deep and narrow valleys, all trending in a south or southeasterly direction. Although not so high above sea-level as the mountains north and south of Thibet, these ranges are an even more effective barrier to travel because they are so continuous and the relief is so great. Not only is there no waterway, but there are no wagon roads, and the building of a railroad would be a stupendous and expensive engineering task. Such a road would necessarily involve the making of a succession of long bridges and tunnels. Here, as in the Central Ranges, settlements are limited to the rare open spots in the bottoms of valleys, and so the population is sparse indeed. The total commerce is very small in volume, because goods must be carried almost entirely on the backs of coolies. The rugged characteristics of the region are evidently the direct result of the recency of the compressive movement which produced the tremendous mountain folds, and perhaps are still more due to the renewed uplifts which have permitted the streams to continue the carving of their deep gorges. This part of China is geologically very young, and to quote the words of the distinguished old geologist of California, Joseph LeConte, "the wildness of youth (here) has not yet been tempered by the mellowness of age."
- Just before the Cambrian period.
- Jurassic period.
- Cretaceous and Eocene periods.