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Cretaceous age of the Red Beds between Yunnan Fu and the Yangtze. In private communications (1936) he has informed me that although these formations are almost indistinguishable from the Cretaceous Red Beds of Szechuan, he has now come to the conclusion that those in the neighbourhood of the Yunnan Lake are probably Permo-Triassic or Triassic, because they directly overlie igneous horizons correlated with the Omeishan Basalt. As for the remainder farther to the north, he believes they are probably Devonian to Carboniferous for they occur below the Permian (?) limestones, and, further, because the late V. K. Ting discovered fossils of Devonian to Carboniferous ages in the Red Beds of Northern Yunnan and their extensions in Southern Szechuan. This find was announced in a private letter by Dr. Ting to Prof. Arnold Heim. My remarks on this problem are given in a later paragraph.
In a later paper Dr. Krejci-Graf altered the classification originally adopted by Prof. Heim and himself and divided the Red Beds
of both Yunnan and Szechuan into an Upper K. Krejci-Graf's Second Classification. and Lower Group.2 The Upper Group is (1931).
stated to be found in precisely the same development from Yunnan Fu to Fulin in Yunnan and thence to Chungking on the Yangtze in Szechuan. It often forms the innermost parts of the troughs and consists of a brick red sandstone complex as a middle subdivision, above and below which are red marls, clays and sandstones. The uppermost division does not everywhere. The lowermost of the three is stated to contain basaltic flows and probably tuffs, in addition to thin coal seams and the various occurrences of salt and gypsum which are exploited locally. It is thought that these Upper Red Beds are of Tertiary age but no definite proof is said to exist. The main portion of the Red Beds of the localities named above, consists of the Lower Mari Group of the Upper Red Beds and Krejci-Graf appears to think that the salt deposits are probably of Tertiary age.
The Lower Red Beds are red and yellow marls, shales, sands and conglomerates with white and reddish, impure limestones in the northern region (Szechuan). Of local and irregular development, they are found between Yunnan Fu and Sitsang (Ningyuan Fu), in the area between Yatshou Fu and Tshingkouho and again to the east of this line, but the occurrences are erratic, SO
1 Ibid, p. 23, footnote, (1932). a Centralblatt für Min. Geol. d Pal., Abt. B, No. 8, pp. 414-415, (1931).
that although present on one flank of a syncline, they may be absent on the other, or, failing entirely in one trough, they may be seen again in the next. No angular discordance was observed between the Upper and Lower Red Beds and the age of the latter is indicated as Cretaceous, on the strength of the Naiadidw which have been found in it. Dr. Arnold Heim is quoted as the authority for this opinion, but, as pointed out above, he no longer holds this view as far as the Red Beds of Yunnan are concerned.
The text of a still later paper by Krejci-Graf on the country between Yunnan Fu and the Yangtze, deals almost exclusively with morphological problems. It contains, however, a stratigraphical table in which the Red Beds are classified as follows :
The Upper Clay Series was only observed in a neighbouring region, presumably Szechuan. · The broken lines in the table indicate discordances. Below the Red Beds lie 500 metres (1,610 feet) of PermoTriassic melaphyre, followed discordantly by 1,100 metres (3,600 feet) of Permo-Carboniferous limestones. Elsewhere, 500 metres of RhæticLiassic coal measures intervene between the Red Beds and the igneous rocks.
On the geological section accompanying this paper the Red Beds are shown in two groups, one of which includes the Brick Red Sandstones, and the other all the strata below them. The latter group
occupies 96 per cent. of the total distance between Ma Ti and the Yangtze (some 48 miles), while the former only occurs in three small, synclinal outliers of limited extent. Further, at the Yangtze itself and again near Ma Ti, the section displays Permo-Carboniferous limestones overthrusted on to Red Beds. This is another point with which Dr. Arnold Heim informs me he does not agreel.
Another account of the expedition during which these observations were made has been published in English but is unobtainable in London. In a private letter, however, Dr. Krejci-Graf states that it adds little to the information given in the papers summarised above?.
W. Credner, who crossed both the Central and Western (Yunlung) Basins, also divided the Red Beds of the former into an Upper and
a Lower Group, separated by a very proW. Credner's Obser. nounced unconformity. He gives a figure of
the critical section near Lufeng Hsien showing a strongly folded, red sandstone-shale formation overlaid discordantly by red sandstones, in which the angle of dip gradually flattens out until horizontality is attained in the uppei most part.
A comparison with conditions in French Indo-China and Siam, both of which he knew, led Credner to attribute the Lower Group, which is probably thousands of metres thick, to the younger Mesozoic, while the upper, undisturbed Group “probably has to be placed into the Middle and Upper Tertiary ”. On his traverse map, the Upper Red Beds are confined to a small area in the neighbourhood of Lufeng Hsien.
The French geologist, E. Saurin, has investigated the country between Yunnan Fu and Yuanyungching, a town in the salt-bearing
region of Central Yunnan, referred to in my The Work of Edmond Saurin. 1933.
own reports as Houching, and shown as such
on Sheet 31 N. W., (1 inch=4 miles), NorthEastern Frontier Surveys, 1899-1900, lying about 25 miles to the east of Tingyuan Hsien (25° 20': 101° 34'). It is one of the more important salt-producing towns of this part of Yunnan, and, in addition, one of the few where rock salt is mined. From Yuanyungching, M. Saurin made his way south through Aluching to the track which leads from Kuangtung Hsien (25° 10': 101° 44') to Yunnan Fu, and was thus enabled to examine completely a limited portion of this region. Restricted though this area may be, the results it has yielded stand in striking contrast with those of the earlier and more hurried traverses1.
1 Geol. Rund., Bd. XXV, Heft 5, pp. 305-312, (1931). 2 Sci. Journ., Sun Yatsen l'niv., Canton, (1931).
3 Mitt. aus dem Geog. Inst. der Sun Yatsen Univ. Kanton. Band 1, Nos. 1 and 2, 1931. An English translation of No. 2 is available.
M. Saurin divides the Red Beds into three subdivisions as follows: (1) A basal conglomerate, resting on a variable substratum,
followed by rapid and versicoloured alternations of sandstones (sometimes calcareous), and of shaly or marly
with rare and thin intercalations of limestone and of
correlated with the Lower Trias. Mansuy's species was originally described from the red shales of the “Terrain Rouge” of Muong On Tai in the Haut
Laos. (3) Compact, fine-grained red sandstones, locally passing into
conglomerates, only found to the west of Anning Chou. The total thickness of the Red Beds in the salt-producing region is estimated at from 2,000 to 3,000 feet.
1 Bull. Soc. géol. France ; 3, 5me Série, pp. 441-473, (1933), Mem. Geol. Surv. Ind., Vol. LVIII, p. 157, (1931).
M. Saurin also refers to the occurrence of Rhætic coal measures at Y Pin Lan (Y’u-pi-lang of Sheet No. 31, North-Eastern Frontier Surveys), a village some two miles south of the Lufêng Hsien-Kuangtung Hsien track and about 11 miles in a straight line west of the former town. At this place, a coal seam, 6 to 9 feet thick occurs, underlain by grey and yellowish-brown clay-shales, friable red sandstones, sandy dark green shales and greenish-yellow arkoses and while the dip of the latter is high to the east, it gradually becomes subhorizontal in the felspathic sandstones. Above the coal seam follows a coarse, white, quartzose sandstone with carbonaceous debris, recalling some occurrences of the grès supérieurs of the Laos and of Cambodia. From the shales enclosing the coal seam the following plant remains were collected :
-Podozamites distans Presl., Clathropteris platyphylla Gæpp. and Tæniopteris cf. Leclèrei Zeiller. These fossils are believed to indicate the Rhætic age of the flora and its analogy with the similar one found in association with coal seams in 'other parts of Yunnan and Szechuan? It is stated that the coal measures are moulded on an anticlinal arch of Red Beds, that there is no appearance of discordance between the upper part with coal and the underlying psammitic sandstones, but that a progressive slowing down of the folding is in evidence here as it is in the Red Beds themselves elsewhere.
It is suggested by Saurin that the upper part of the Red Beds which occurs in full development a short distance further north passes laterally into the psammitic sandstones, carbonaceous shales and coarse, white sandstones of the coal measures and that the latter would thus be the stratigraphical equivalents of the compact, soft red sandstones which terminate the Red Beds about Lufeng Hsien. The coal measures are believed to represent the deposits of an ancient contemporary depression, doubtless lagunar at first and then becoming lacustrine; the products of erosion and the results of slow, orogenic movements. It follows that the Red Beds, the upper part of which passes into a Rhætic, or as some palæobotanists would probably consider, a Norian horizon, dated by its flora, must be older than this.
1 Mem. Geol. Surv. Ind., Vol. XLVII, Pt. 1, pp. 66-69, (1923).
Rec. Geol. Surv. Ind., Vol. LIV, Pt. 1, pp. 78-82, (1923),