Imagens das páginas

e and canali Jhora

area, and the narrow neck of land which separates the Kali Jhora and the Sivok Jhora is gradually giving way.

Just under the bridge over the Kali Jhora the rock is a much fissured gray sandstone, dipping very high, almost vertically, in a north-western direction. There is evidence here of great disturbance.

Proceeding from the bridge northward for about five furlongs, there is found a great development of sandstones with thin seams of coal and occasional bands of carbonaceous shales, striking N.E.-S.W. The seams are scarcely over a foot and a half in thickness, but some of the coal is of fair quality and cakes.

The following section just north of the junction of the Kali Jhora with the Tistá gives an idea of the mode of occurrence of the coal:

2.--Brownish sandstones with very thin seams of coal.
2'.-Good coal.
12'.-Sandstones with strings of coal.
I'.-Good coal.
4.-Rather soft brownish sandstones with very thin seams of good coal.
The strata are rather contorted. Usual dip N.N.W. about 70°.

Further northward, along the river, rock is not so uninterruptedly visible. Here and there quartzitic sandstones, and at one place rather soft sandstones, are met with.

Close to the junction of the Sitikhola with the Tistá, the Dalings come in, their dip as well as that of the Damudas being northern.

North of the rest-bungalow on the Kali Jhora, and west of the cart-road, there is a flat some 200 feet above the road, and about 300 above the river bed. The greater portion of its thickness above the road is formed of recent deposits-alternations of sand and shingle ; the latter at places compacted into hard rock.

The following section of the Damudas in the Kali Jhora, commencing from the bridge in ascending order, partly natural and partly exposed by digging, may be given here.


17'.- Rather soft sandstones with thin seams of coal ; dip very high. . 43'.—Rather soft sandstones with thin seams of coal; dip very high, with occasional

bands of carbonaceous shale. Dip N. N. E., 60°. The sandstones are fine grained and partly ferruginous. They are intersected by joint planes, the faces of which are very smooth and are encrusted with thin films of carbonaceous matter. The strike of these planes here is E.N.E.-W.S.W., and the inclination is nearly vertical and

southern. 28'.- Rather massive sandstones with abundance of carbonaceous matter and

very thin seams of coal. 3'.-Finely laminated sandstone. The strike here becomes E.N.E.-W.S.W. 6'.- Good coal. 6".-Carbonaceous shale. 1'.-Good coal. The thickness of these thin seams of coal is very variable. 29'.-Massive sandstones.

7.-Good coal. 51:-Sandstones with thin bands of carbonaceous shales crumpled up

together. 1'.--Good coal. 2' 9".-Sandy carbonaceous shales and very thin coal. 60'.-Massive, gray, much fractured sandstones, with a little occasional carbona

ceous matter. The strike, here is very nearly E.-W. 5'.—Thin sandstones and coal crumpled up together. 7'.- Rather soft, whitish sandstones. Bedding planes strike nearly E-W.

These are cut obliquely by joint planes striking N. E.-S. W. Car

bonaceous matter occurs in thin foliæ along these planes. 2'.—Thinly laminated carbonaceous shale and coal crumpled up together. Here

the strike changes to E.S.E.-W.N.W. 5'.-Thin sandstones and carbonaceous shales crumpled up together. 1'.-Good coal. 42'.—Rather massive, soft sandstone. 4.-Carbonaceous shales and coal crumpled up together. II'.-Sandstones. 2'.-Carbonaceous shale and coal. 2.- Coal. 2'.-Sandstones. 2'.—Carbonaceous shale and thin coal. 15'.-Sandstones. 3.-Carbonaceous shales with thin coal. 3.-Sandstones. 3' 6'.-Carbonaceous shales and coal. 8' 6".-Sandstones. 3.-Carbonaceous shales. 3'.-Coal with thin lenticular bands of quartzite. 6'.-Coal with bands of thinly laminated quartzitic sandstone. At one place

one coal seam was found to be a liule over 2 feet in thickness, but traced along the strike the thickness was found to be reduced

to a few inches. Dip W. N. W. 23'.—Sandstones. The dip here changes to N. N. W. 1' 6".-Good coal, with very thin lenticular bands of quartzite. 9'.-Sandstones with abundant carbonaceous matter. 1' 9'.—Good coal.


[The section is more or less covered up for two furlongs.] 13'.-Sandstones, false-bedded, buff, fine-grained, fespathic, with nests of

carbonaceous matter. 3.- Rather soft sandstones with thin coal, the two crumpled up together. 5.-Rather soft gray sandstones. 5':-Carbonaceous shales, thin seams of coal, and thin lenticular bands of

quartzitic sandstones.

1'.-Fine-grained ochreous sandstone, 20'.-Fine carbonaceous shales with thin seams of coal and occasional bands

of ferruginous sandstone, the whole crumpled up together. 21'.-Sandstones with occasional nests and strings of carbonaceous matter. 5:--Thinly laminated carbonaceous shales with thin seams of coal, not more

than 2 or 3 inches in thickness. 3'6".-Highly felspathic sandstones. 9".-Carbonaceous shale. 13'.-Felspathic sandstones. [The dip so far is N.N.W. about 60°.] 2' 6"-Carbonaceous shales and sandstones. The dip here becomes W.

N. W. 1' 6".-Rather good coal. 7.-Whitish felspathic sandstones. 1'9".-Carbonaceous shale with very thin coal, 14.-Sandstones. 5.- Rather soft, thinly laminated, brownish sandstones with abundant carbona

ceous matter. 2.-Carbonaceous shale with thin coal, 8'.-Sandstones. 1'2".-Coal. 15.-Sandstones with thin seams of coal. 21.—Thinly laminated sandstones and carbonaceous shales with thin coal. 5'.-Carbonaceous shales with thin coal. 5'.-Grayish sandstones with coal, of which one seam is about 9 inches in

thickness. The dip here changes to N.W. 24'.—Massive gray sandstones with abundance of carbonaceous matter. 30'.- Partly covered up, partly thinly bedded sandstones and carbonaceous

shales. 9":— Rather good coal. 7.- Alternations of hard, dark shale and thin sandstones. 6".-Coaly shale. 10".-Coal. 1.-Carbonaceous shale. 1'.-Coal. 3.-Shale. 1'.-Coal. 172'.-Sandstones, carbonaceous shales, and thin seams of much altered coal,

the whole much crushed and crumpled up. The sandstones prevail. They are mostly quartzitic; and those in contact with the coal have their contact surfaces smoothed and polished, and indented into

hollows and furrows in a peculiar manner. 450'.—Mostly covered up. . Some coaly shale, sandstones, &c., are exposed in

a streamlet about half way. 3'.-Coal. 48'.- Alternations of rather soft, fine grained sandstones, carbonaceous shales

and thin coal. The dip is very high all the way. Strike N.N.E. . S. S. W.

mali chin e

ta bere liberis sergantie handeling en




Further up the Kali Jhora there are met with, first quartzites and quartzitic sandstones, and then a succession of crumbly, intensely fractured, greenish gray gritty mudstones, quartzites and carbonaceous shales with thin seams of coal which continue to the head of the Jhora.

(6)– West of the Tista Valley.

Proceeding westward the band of the Damudas is found to be considerably attenuated along the Látpanjor spur. They widen out again by the Mana Jhora, a tributary of the Mahanadi. There are several seams of coal in the reserved forest east of Mana Jhora, but they are much disturbed and greatly altered by igneous intrusions. Several outcrops of coal are visible in the Mahanadi; one just below the godown of the Simring. Tea Estate, measured 11 feet. The dip is rather high, about 65°, and usually points N. N. W.

The high scraggy ridges, formed of massive Tertiary sandstones and conglo. merates sloping with the dip slope which form such a characteristic feature in the landscape between the Chel and the Mahanadi, lose their definition south-east of Tindáriá, and are almost entirely lost by the railway at Sepoydhurá (Rungtong). Hence westward, as far as Phankhabári, the Tertiaries are not distinguishable from a distance. This loss of definition is due to attenuation, as well as to the absence of the massive conglomeratic bands.

Along the railway line the Tertiary boundary which, as usual, cannot be drawn without difficulty, is just a few yards below the railway station at Rungtong. Hence proceeding northward (nearly across strike), alternations of shales, sandstones, and thin seams of coal are met with. The thickest of the coal seams is not more than 3 feet in thickness. The shales, which are rather soft and slightly ferruginous, predominate about Chunbatti, and just at the loop here a thin seam of indifferent coal is exposed. Beyond this there is an immense thickness of slaty shales and flags on which the Government Engineer's bungalow stands. We then come upon alternations of sandstones, carbonaceous shales and coal which extend up to the Railway Station at Tindaria. The Dalings come in just a little beyond. As the section about Tindaria have been given in detail by Mr. Mallet, and as my diggings did not disclose any seam of importance, it is needless to give details of the latter.

The several branches of the Chirangkholá expose a number of coal seams, but none of more than 6 feet in thickness, and none that would cake.

The Rattundong tea garden (included in the Selim tea estate) west of the Rohini river, stands on a gently sloping bay-shaped flat, about 6 furlongs wide. It is strewn over with huge masses of gneiss, which must have come all the way from Kurseong; and its thickness is made up of recent detrital deposits, in which large partially rounded blocks of gneiss and quartzite prevail. Rock is seen in situ only in the bed of the Rohini, and there, too, it is less often seen than not.

The Rakti exposes a much better section, which has been described by Mr. Mallet. The Bámanpokhri flat just west of the Rakti is similar to the Rattundong flat just mentioned. In some ravines at the head of this flat several rather promising outcrops of coal were encountered, but digging through them they were found to be of small thickness.

(c)- Quality of Coal. The following table contains the analyses of a few samples made in the Survey laboratory :

[ocr errors][merged small][merged small][merged small][merged small][ocr errors][ocr errors][merged small][ocr errors]


Cakes, but not Does not cake, Cakes, but not Cakes, but not
buts sinters strongly.

strongly. Ash, light gray. | slightly. | Ash, light red. Ash, light gray.

Ash, light red.

Notes on the Geology and Mineral Resources of Sikkim, by P. N. Bose,

B.Sc., F.G.S., Deputy Superintendent, Geological Survey of India, (With one map; [will appear in next part of the Records].)

1.- PHYSICAL GEOGRAPHY. To the east Sikkim is bounded by a ridge which forms the watershed between it on one side and Bhután and the Chumbi portion of Thibet on the other, the streams on the Sikkim side being tributaries of the Tistá and those on the Bhután and Chumbi side feeders respectively of the Jaldhaka and the Torsá. The ridge, which is sometimes called the Cholá range from one of the passes in it, rises in elevation northward, the principal peaks proceeding in that direction being Lingtu (12,617 feet), Gipmochi (14,523 feet), Chukurchi (15,283 feet), Dopendikáng (17,325 feet), Black rock (17,570 feet), and Powhunri (23,190 feet). The chief passes on the eastern frontier are Pembiringo, Jalep (14,390 feet), Cholá (14,550 feet), and Thankalá (16,000 feet).

The northern boundary is drawn on the Survey map (Sheet No.7 N.-W.) along a lofty snow-capped ridge of which Kanchanjháu (22,550 feet) and Chomiumo (22,2 90 feet) are the best known peaks. The natural line of watershed lies a little further north along a less elevated ridge passing through Bhomtso north of the Cholamo lake; and the boundary in a more recent map' is drawn along this line. The streams to the south of it are feeders of the Tistá, and those to the north are tributaries of the Arun. The best known passes on the northern frontier are Donkiá (18,100 feet), Kongrálamu (16,000 ?), and Naku (17,000 feet).

i l'ublished in the Survey of India Report on the explorations in Sikkim, Bhutan, and Thibet (1889).

« AnteriorContinuar »