OF THE NILE AND GANGES. 



645 



being marine, in all amounted to twelve or thirteen. In 

 designating the formation as Pliocene, which I have done 

 during many years, I have been guided by the indications of 

 the Mammalian fauna, as intermediate between the Miocene 

 of the Irrawaddi, Perim Island, and the Sewalik hills, and 

 that of the existing period. 



4. General Inferences. — I shall now briefly indicate the 

 inferences to which the observations on the section of the 

 Jumna lead. 



1. That the Doab alluvium, intersected bv the Granges and 

 Jumna, consists of fluviatile sedimentary deposits, the in- 

 ferior portion of high antiquity. 



2. That there are no indications of its being anywhere 

 overlain by deposits resulting from marine submergence. 



3. That during the progress of alluvial deposition the area 

 now constituting the plains of Hindostan was probably 

 subject to movements of upheaval and depression, analogous 

 to or corresponding with those which have been demon- 

 strated to have occurred in the delta of the Ganges. 1 



1 MS. Note written by Author in 

 1844. ' The conditions under which 

 Oceanic deltas are formed, iipon the 

 verge of the sea, preclude the occurrence 

 of sections, so as to show how the de- 

 tails of the daily progressing strata are 

 arranged. Our knowledge in such eases 

 is ordinarily limited to the superficial 

 banks of the rivers and creeks, through 

 which the tidal currents scour. Hap- 

 pily, the desired information in regard 

 to the delta of the Ganges has in some 

 measure been supplied by boring opera- 

 tions, which have of late years been car- 

 ried nearly 500 feet below the level of 

 Calcutta, the results having been care- 

 fully recorded in the Indian journals. 

 These borings were begun as far back as 

 1804, and have been repeated at dif- 

 ferent periods, the last and deepest ex- 

 cavation having been carried on between 

 the years 1836 and 1840, under the 

 superintendence of a committee of engi- 

 neers. 



' Calcutta is situated in the midst of 

 the delta of the Ganges, upon the banks 

 of the Hooghly, within the range of the 

 tidal current. The surface soil consists 

 of ten feet of fine mud or inundation 

 sediment, which is succeeded in the de- 

 scending order by a bed of blue adhe- 

 sive clay, 40 feet deep. The lower por- 

 tion of this clay abounds in decayed 

 vegetable matter, part of which is in the 

 condition of peat mixed with fragments 

 of rcd-colourid wood, hardly altered, 



which Dr. Wallich was enabled to iden- 

 tify with the Soondree of the creek 

 forests. Next follows a bed of ten feet 

 thick of the concretionary argillaceous 

 limestone, which, under the name of 

 " kankar," occurs abundantly in many 

 parts of India, in the form of irregular 

 nodular masses. Then succeeds a bed of 

 green siliceous clay, 15 feet thick, the 

 lower portion of which also furnishes 

 kankar-nodules. At 75 feet below the 

 surface, variegated sandy clay begins, and 

 continues to a depth of 45 feet. This is 

 succeeded by thin beds of clay marl, 

 loose friable sandstone, and a sandy clay 

 abounding in weathered fragments of 

 mica-slate, and waterworn nodules of 

 hydrated oxide of iron. At 175 feet a 

 soft conglomerate, 10 feet thick, is met 

 with, consisting of gravel cemented by 

 a. clayey matrix, together with sharp an- 

 gular fragments of quartz and felspar, 

 larger than peas, and resembling in 

 every respect the debris of granitic rocks 

 which have suffered little attrition by 

 transport from a distance. The gravel 

 passes gradually into an indurated fer- 

 ruginous sandy clay abounding in scales 

 of mica, which continues with little va- 

 riation through a depth of 18 feet. A 

 thin stratum of soft sandstone occurs 

 next, succeeded by beds of sand and 

 sandy clay extending with great uni- 

 formity of character through a depth of 

 172 feet. The lower half of the hume- 

 rus of a ruminant, apparently a species 



