Page:Journal of the Asiatic Society of Bengal Vol 29.djvu/386

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356
On the rocks of the Damúda group.
[No. 4.

stance that most of the best seams occur in a group of rocks unrepresented in other fields. It is not known to which group the beds of Palámo Rámghar or[1] Central India belong.

Above the Damúda beds, and slightly unconformable upon them, occurs a series of coarse false bedded sandstones, with intercalations of red and grey clays, passing into shale in places. These beds are mainly developed in the Southern portion of the Rániganj field, where they form the mass of the fine hill of Panchit (Pachete), whence the name of Panchit series is suggested for them. The upper part of Panchit Behárináth and Garanji hills are composed of a coarse conglomerate, differing in mineral character from the lower portion of the formation.

This lower portion is of considerable interest, for, besides plants, the first distinct animal remains yet discovered in Bengal have been procured from them. These consist of various biconcave vertebrae and other bones, jaws and teeth, apparently reptilian, and of a small crustacean allied to Æstheria. The plants include, besides numerous peculiar forms, the Schizonema? so characteristic of the Rániganj series.

The Æstherias appear identical with those found by Mr. Hislop in the Mangáli shales of Nagpúr. From these shales was also procured a reptile, Brachiops laticeps of Owen, belonging to the same group as the Labyrinthodon. It seems probable that the Mangáli shales are the representatives of the Panchits of Bengal. The Upper Damúdas of Jabbalpúr may also be of the same age.

In the Rájmahál hills the Lower Damúdas are unconformably overlaid by a series of grits, conglomerates, and white clays. Above these, also unconformably, occur enormous flows of basaltic trap, with interstratifications of white and black shales, abounding in plants of the genera Zamites, Pterophyllum, Pecopteris, Tœniopteris, &c.,

  1. Beds containing plants of Damúda age occur also at the base of the Himalayas of Sikkim, a circumstance first noted by Dr. Hooker, in his “Himalayan Journals,” Vol. I. p. 403, and confirmed by myself in 1856. Nothing however could be made out of the extent of the beds, which are distinct from those containing coal on the Tista river. The only evidence of the existence of Damúdas were specimens of glossoptcris and vertebraria found in loose blocks in a stream below Pankábári.