1860.] On the rocJcs of the Damúda group. 357 



all quite distinct from Damúda forms. These beds were first accu- 

 rately described by Professor Oldham in a paper published in tbe 

 Society's Journal for the year 1853. They have since been named 

 by him the Hájmahál series. It was, however, at first thought that a 

 slight passage existed between the Damúda and Rájmahál groups, a 

 view which Professor Oldham has since announced to be erroneous ; 

 the passage, if any exists, occurring in the conglomerates and grits 

 interposed between the two series. Memoirs of Geological Survey 

 of India, Vol. II. pp. 313, 325. 



The conglomerates and grits of Panchit hill, provisionalby termed 

 the Upper Panchits, agree perfectly in mineral characters with those 

 underlying the traps in the Rájmahál hills. As there is every proba- 

 bility that they occupy the samo position in the general series, it is not 

 unreasonable to suppose that they are an extensión of the same beds. 



A still higher group occurs in Orissa and in Central India, to 

 which the ñame of Máhádeva has been given. No representatives of 

 it are known in Bengal, and it is possibly considerably higher in the 

 series than any of the groups abo ve mentioned.* It is not by any 



* Professor Oldham has suggested as probable that it is of Nummulitic (Mid- 

 dle Eocene) age. (Mem. of the Geological Survey of India, Yol. I. p. 171 and 

 Vol. II. p. 210 note), and there are doubtless arguments in favor of his sugges- 

 tion. But the Máhádevas are in Central India overlaid uuconforrnably by an 

 intertrappean series abounding in a shell, Physa Prinsepii, said to be very closely 

 allied to Physa Numrnulitica of D'Archiac from the Nummulitic rocks of the 

 Panjáb, if not identical with it. (See Hislop on the Tertiary beds and fossils of 

 Nagpúr, Quarterly Journal, Geological Society, Vol. XVI. pp. 163, 164). By 

 D'Orbigny (Prodrome de Paléontologie, II. 299) Physa Prinsepii was considered 

 identical with P. Gigantea, Du Boissy, from beds near Eheims which are of the 

 lowest Eocene age, even below the plástic clay, while Nummulitic rocks are con- 

 sidered by the best authors on the subject, as, at lowest, middle Eocene. There 

 is much general similarity of facies between the fresh water (? land) shells of the 

 Eheims beds (Mem. de la Societé Geologique de France 2e. serie, Tome II. píate 6) 

 and those of the intertrappeans of Central India. The identiíications of the 

 Physas are dubious, especially that of D'Orbigny, but the resemblauce of the 

 facies is important. So far as this eviclence goes, it tends to point out the inter- 

 trappean beds as at least as low in the series as the Nummulitics and possibly 

 lower. In this event, from the great break between the intertrappeans and the 

 Máhádevas the latter must, a fortiori, be of pre-Nummulitic date. But all the 

 evidence either way is of an extremely slight description. 



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