§ Research in Ohine Vol. I p. 23ö.

87

THE PHYSIOGRAPHICAL HISTORY

OF THE YELLOW RIVER BETWEEN SHANSI AND SHENSI

BY C. C. WANG. (M)(National Geo'ogical Survey of China, Peking)

INTRODUCTION

The Yellow River flows across seveu provinces of China and has a

considerable length roughly estimated at nine thOusand li. This paper will

deal with the physiographical development of tbe middle course of the river,

i.e., the river between Shansi and Shonsi provinces. An earlier study basbeen matte by Bailey Willis in 1901. His route was from Taj Yüan (*J),capital of Shansi, south-westward across the Yellow River to T'ung Kuan

(* a district city of Shensi, just on the right side of the river. He con

sidered the Yellow River as a youthful stream without any earlier history.

Hesaid:"Near the. border of Shansi and Shensi let it he assumed that the

Huang.t'u formation was spread upon a relatively mature surface of erosion,

and that its accumulation formed an extensive plain f aggradation, in which

the old topography was to a considerable extent buried. Let it be assumed,

furthermore, that this surface was tilted, so that the northeastern portion lay

highe and the southeastern portion lower; that is, that i.t was depressedtoward the down-throw of the great normal fault-blocks of Shansi and Shensi.

Prior to the tilting there may have existed a large river, the initial Huang-ho,

which meandered in the graded valley on the Ruang-t'u, or as a result oftilting, a large stream may have developed by rapid head-water erosion and

repeated capture, taking a consequent course on the tilted surface. The

latter, in view of the present course of the river, ftom the highlands of Mon-

golia towards the lowest point of the down-throw of the great fault system of

the Taj- Hua-Shan, seems to be the more probable origin of the -Huang-ho.'

From my recent study of the geology in Shansi, it seems evident

that the effect of the Tai-Hua-Shan (j Lii) fault can only depress the

region south of the confluence of the Yellow River with the Fen Ho

88 Bulletin of the Geological Society of China

while that north of the confluence of the rivers may, on the other hand, be

*tplifted by the main fault along the Feu-Ho valley as an upthrow-side. More-

over the upper portion of the Yellow River in the Sui-Yuan area is mostprobably situated on the downthrow nido of the Yiñ-Shan (di) fault.

All the facts seem to indicate that the tilting of the wholo region,

except the south of the confluence of the Yellow River and the Fon Ho,towards the downthrow of the Tai-Hua-Shan fault is impossible.

On the basis of our recent observations it is evident that the middle

Yellow River possesses a complex history of development which may bedistinguished into successive stages. Before entering into discussion of its

history, the general featureS of the valley will be firstly stated.

DEicÛRIPTTON OF PEA TURES OBSERVED

At the village Ho ¡C'en (so) in the Tokto district; theYellow River leaving the Kuei-Sui plain and changing its w-x directionturns southward into the hilly land between Shansi and Shensi in a N-Sdircton. Its channel in the latter direction is in average more than 200 m.

wide, though it sometimes widens to 300 in. or more and occassionally islimited only to 40 m. in width. The geological formations crossed by the

river between Ho K'ou. and Pao Te () city mostly are the Cambre-Ordovician limestone and Fermo-Carboniferous coal series; in the south of Fao

To city till the vicinity of Chi lisien the Mesozoic red shale and sand-

stone; and further south, the Palaeozoic limestone and Archean gneiss.Especially regarding the topography of the river valley the author has under-

taken two sections as below -

In 1920 the author made a journey from the water-shed between the

Yellow River and the Feu Ho westward to the valley of the former. By this

trip it has been observed that from the divide in question, which is in average

more than 2,000 meters high above the sea and about 120 Ii distant from the

valley of the Yellow River, the surface of the hilly land gradually descends

westward. The siope suddenly increases when the channel of the rivercomes in view, At Lin Chê Yii Fao Tê lisien, the altitude of the

cliffs on the bank of the river is reduced only to 1000 m. above the sea, while

Wang:Physiographi Hisorj of the Yellow River 89

that of the river level is about 900 ni. From here to Pao TO city the river

flows through deep canyons. In the vicinity of the city on the ridges of more

than 1000 m. above the sea near the river bank are often exposed the remains

of a conglomerate with predominant limestone pebbles, which seems to be the

deposit of an old stream. Here the topography of the river valley may be

illustrated by the followingßgure.

Represents the inclined surface of the hilly land above thecanyon.

The Conglomerate remains on the slope.

The cliff of the canyon ; and D, the gully on the bed of the canyon,

which is only visible in winter when the water is much reduced.

From Pao TO to Wo Ch'fi (tn) city one may take a trail onthe river bank. On reaching Hsün Chien Sau («3), a village of the HoCh'ü district, the river is out of canyons and begins to flow in a wider valley,

but at Hou Yao P'o (Ij) N.W. of the Ho Ch'fi city it enters the Ordoni-cian limestone area and cuts again in a gorge. Further up the stream to Shih

ChOng Ts'un (ff), Ho Ch'ü.Hsien, on the ridges of about 1400 m. abovethe sea, the trace of limestone conglomerate has been also discovered and hero

the adjacent river level is about 12.50 m. In approaching 10 Ii eastwardfrom Shih ChOng Ts'un to Pien Kuan city, the elevation of the hills has been

increased to 1600 m. above the Sea,

In 1923 another section has been observed on the route from Stil TO

() eastward to Wa Pu (j) city on the right side of the Yellow Riverin Shensi province. On reaching the village of Shih Tui Shan (*tIi)which is about 20 ii distant from Wu Pu city, the elevation of the hillscrossed begins to decrease rapidly eastward and at a distant view it is clear

that the river flows in a belt of depression. At Sung Chia Ch'uan (*))Wa Pu I-Isien, on the right side of the river opposite to Chün Tu () inShansi on the left side, the river level is more than 600 ni. above the sea.

90 Bulletin of the Geological Societj of China

Two li down the river below Sung Chia Ch'uan the walled cliffs of red sand-

stone have an average altitude of about loo m. above the river level. Seven

li from Obün Tu southeastward to Li Chia Yüan (j) the elevation oftue hills increased to 1,000 in. above the sea.

PHYSTOGRAPHICA L STA GES

From the observatiorLs stated three stages of physiographical develop-

ment can be distinguished in the Yellow River valley between Shansi' and

Shensi:

An old valley of advanced maturity. It bas been shown that

the present channel of the Yellow River is developed in a wide, opon and

probably preexisting valley. The feature of this wider valley seems to denoto

an old stage of advanced maturity. Whether such valley is the ancient

initial Yellow River or not can hardly been decided, but it should have been

developed by a stream probably still larger than the present Fon fo. The

conglomerate remains in the vicinity of the Fao TO city and Shth Chêngvillage are most probably the the deposits of this old stream.

The canyon of youth. As the present Yellow River sub-sequently flowed through the old valley of the above stage and the land 'was

then uplifted, the river recato its present canyon in the old valley. The

movement of the uplift is considered to be effected by the normal faults which

have produced the famous falls at Ha Kou ( U) and Lung Men (9) inthe southern part of the Shansi-Shensi border.

The gully due to very recent warping. The gully is developed

on the agraded bed of the canyon as already shown in the preceding figure.

It is usually filled with water even in the winter; but without doubt it is due

to the latest active erosion resulting 'from the very recent local up-ward.

In the neighbourhood of La Yü kou (*U), s. w. of HsingHsien (J) the river bends abrüptly to the west and in flowing over more

than 30 li it again turns to south, in its original N. s. direction. The cause

of such bending of the river is thought to be due to the elevation of thesouthern hills round Tze Chin Shan (ili) which is an igneous bodyintruacd in the mesozoic sedimento.

Wang:Physiographic Hi3ton/ of the Yellow River 91

CORRELATION OF THE PIIYSIOG.RAPHIOAL STAGES GLASSIFIED

WITH TB OSE NAMED BY WILLIS AND WITH THE GEOLOGICAL TIME SCALE

As the feature of the old valley formed previously to the present

Yellow River is of advanced maturity, it is probably equivalent to the Tang-

Usien stage of Willis. The young canyon of my second stage may correspond

to Willis' Feng Ho stage. The gully on the river bed is not described by Willis

but it is distinctively a different stage younger than that of Fon Ho, because

it only shows a recent local warping and begins to be active after the canyon

of the Feu Ho stage has been established. As it is first observed in thechannel of the Yellow River, I propose to call it the Huang Ho stage.

Concerning the geological time scale, as the Hipparion clay which

covers the Tang Hsien stage has been proved to be lower Pliocene or upper

Miocene age, the old valley of the first stage in question had been con-sequently formed during Miocene. The development of the canyon of the

second stage may be assigned to Pleistocene, whiis the gully bas been cut in

the recent period.