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Table of Content

    15 July 1981, Volume 36 Issue 3 Previous Issue    Next Issue
    THE FORMATION AND TYPES OF PEAT IN CHINA ANDTHE LAW OF GOVERNING ITS DISTRIBUTION
    Chai Xiu
    1981, 36 (3):  237-253.  doi: 10.11821/xb198103001
    Abstract ( 722 )   PDF (803KB) ( 1259 )   Save
    The peat in China has been formed chiefly in various periods since Holocene.The peat deposit reached its acme in Miocene.In China, there exist three types of peat, subdivided into fourteen kinds. Amongthem, the low-moor earex peat ranks as the principal one. The high-moor peat andmedium-moor peat are rather scanty. They are sporadically distributed in small areain regions as Daxinganling, Xiaoxinganling and Changbaishan.The total peat area in China, approximates to 4,159,000 hectares, about 0.43% ofthe total area of China. Its reserve amount is about 2,702 million tons (air-dryweight), in which, the exposed peat is about 80% and the buried peat 20%. Theirdistribution is unblanced. The exposed peat occurs mainly in Daxinganling, Xiaox-inganling, Changbaishan and Sanjiang Plain. Its reserve is about 56% of the wholereserve of China. The peat reserve in Qing-Zang Plateau comes next, constituting 19%About 10% of buried peat is concentratively distributed in the Eastern Plain.The Peat regions in China are classified into six large regions. The exposed peatand buried peat prevailed in the above mentioned three areas respectively.
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    THE CALCULATION AND ANALYSIS OF THE HEATEXCHANGE BETWEEN THE GROUND SURFACE AND THEDEEPER LAYER OF SOIL IN CHINA
    Gao Guodong, Lu Yurong
    1981, 36 (3):  254-266.  doi: 10.11821/xb198103002
    Abstract ( 471 )   PDF (679KB) ( 310 )   Save
    There are many formulas to calculate the heat exchange between the ground surfaceand the deeper layer of soil. The best one is to calculate it according to the changeof heat content in the soil layer, where the temperature varies during a time in-terval.
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    THE VERTICAL ZONATION OF MOUNTAINYEGETATION IN CHINA
    Liu Huaxun
    1981, 36 (3):  267-279.  doi: 10.11821/xb198103003
    Abstract ( 1985 )   PDF (841KB) ( 1649 )   Save
    On account of vast territory and complex physico-geographical conditions as well aagreat human impacts, the distribution of mountain vegetation in China is very compli-cated. Yet, law of zonation still holds true. The structure and character of mountainvegetation change along two directions, i.e., from south to north and from east to west.In the eastern part of China altitudinal vegetation-belt spectrums change mainlyfrom south to north.1. Warmth-like types of altitudinal vegetation-belt spectrums being replaced bycold-resistant types with alternation of basic vertical vegetational belts from evergreenbroad-leaved forests to deciduous needle-leaved forests.2. Diminution of number of altitudinal belts and simplification of their structures.3. Lowering down of altitudes of altitudinal vegetational belts. On mountains inwestern part of subtropical zone lies the highest altitude of timberline in the world, witha maximum altitude of over 4,400 m above the sea level. It lowers down towards northby over 100 m per degree of latitude.4. Occurrence of dominant belts in vertical profiles of mountain vegetation de-pends upon the nature of horizontal zones. The dominant belts in typical geographicalzones are certainly the basic vertical vegetational belts. And in transitional zones theyoccur above the basic vertical belts.While in the arid and semi-arid western part of China, changes of altitudinal vege-tation-belt spectrums are quite different. They take place chiefly from east to west. Itis worthwhile mentioning that structures of vegetation-belt spectrums are very simpli-fied, steppes and deserts occupy the dominant position on mountains and all altitudinalvegetational belts ascend in this direction.
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    APPROACH TO THE GENESIS OF THE TAKLAMAKANDESERT
    Wu Zheng
    1981, 36 (3):  280-291.  doi: 10.11821/xb198103004
    Abstract ( 1081 )   PDF (903KB) ( 2218 )   Save
    The distribution of land and sea, the violent rise of Qinghai-Xizang Plateau, thechange of the inclination of the axis of rotation of the Earth and the horizontal dis-placement of the structure caused the climate of the Tarim Basin, which is situateddeeply inland, to become very dry and the aridity has been further intensified sincethe Quaternary period. All the above mentioned factors provided favourable climaticconditions for the formation and development of desert. In the humid times of theQuaternary period, a great number of rivers fed by a great amount of melting snow, de-posited a thick and loose sand layer in the basin which became a rich source of sand inthe desert.The present dimension of the Taklamakan desert has been gradually developedsince the Middle Plesistocene period. As the dryness of the climate increased, the desertextended from the center of the basin to the periphery and from east to west.The topography of the tremendous intermountane basin of Tarim greatly in-fluenced the air current and was favourable to the development of transverse sanddunes. This types of sand dunes predominates the Taklamakan Desert. Longitudinalsand dunes were formed under the action of helical turbulent flow of the atmosphereand they were mainly distributed in the central part of the desert, where the aircurrent was not interfered, so that in the plain area of ancient delta, the wind direc-tion remained unchanged.
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    THE DYNAMIC OF WATER-SALT IN THE SOIL AND THEACCUMULATION AND DISPER5ION OF SALT ONNORTH CHINA PLAIN
    Xia Zenglu
    1981, 36 (3):  292-302.  doi: 10.11821/xb198103005
    Abstract ( 639 )   PDF (720KB) ( 470 )   Save
    According to the water condition, form characteristics and the dynamic type ofthe salt in the soil, the dynamic type of the water-salt may be classified into six types:1. The dynamic type of the water-salt moistened by leaching;2. The dynamic type of the water-salt moistened by the film water and capillarywater;3. The dynamic type of the water-salt moistened by the substratum capillary water;4. The dynamic type of the water-salt moistened periodically by the capillarywater;5. The dynamic type of water-salt moistened by the support capillary water;6. The dynamic type of the water-salt moistened by the saturated capillary water.The seasonal change of salt accumulation of soil surface has a particular characterin this region. In general, the condition of the water-salt in the soil not only deter-mines the period and extent of the accumulation but also determines the effectivenessof salt washing It may control the seasonal process of the accumulation.According to the correlation analysis, it reveals that there is a good correlationbetween the degree of mineralization of ground water and salt content inthe substratum.
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    FACIES AND SEDIMENTARY MODEL OF THE LUAN RIVERDELTA
    Gao Shanming
    1981, 36 (3):  303-314.  doi: 10.11821/xb198103006
    Abstract ( 599 )   PDF (801KB) ( 864 )   Save
    Since the Holocene, five secondary deltaic units, belonging to five differentstages have been built. They belong to the Early Holocene (8,000 years B. P.), theMiddle Holocene (8,000 to 3,000 yrs. B. P.), the Early Historical (3,000 to 900 yrs. B.P.), the Late Historical (900 to 100 yrs. B. P.) and recent periods (since 1915) re-spectively.Although the magnitude of the five secondary deltaic units and the respectivepcation of the river mouth varied in different stages, the formation of the delta fol-lowed always the same process.Luan River is a heavily sediment-laden river on the north shore of BohaiBay. In flood season, this river is characterized by abrupt rising and falling ofwater, hence the capacity of sediment transport. That is why the river channels arehighly braided and frequently change their courses, and the delta advance quicklytoward the sea.As the tides are low along this part of coast, Luan River Delta develops underthe joint action of the river and the sea waves. The mid-fine sands carried by theriver into the sea are deposited mainly at the river mouth. They are soon workedupon by the waves and constructed into sand bars which are roughly paralled to thedelta front. To the south of the present Luan River mouth, there are four groups ofsand bars and islands arranged in echelon, that is each group is a little off set to thewest than the group just to the north of it. We may conclude that the more pro-truding the sand bars are, the more recently formed they are.The scouring or silting change of the delta front depends on the quantity of sedi-ment coming from Luan River. The Recent Delta, owing to the abundance of incom-ing sediment is fast prograding. The Late Historical Stage Delta, as it is still withinreach of the sediment from the present river, still retains its fringing sand barsintact, while at the mouth of Daqing River and to the west of it, some of the sand barsbelonging to the deltas of earlier stages are disintegrating into islands and the deltaplain has been turned into tidal flats as sediment supply from the river is no longeravailable and wave action predominates.
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