Chap. YIL] more recent beds. 139 



the present one, seems to point to a geographical configuration of the 

 land very similar to that now existing. 



II. Laterite. 



Concerning this rock but little need be said. It covers a considerable 

 space to the East of the Raniganj field, and patches of it occur within 

 the area resting upon the Damudas. It is uniformly gritty, and contains 

 fragments of sandstone, evidently derived from the neighboring rocks. 

 It attains no great thickness, being seldom seen to exceed 5 or 6 feet. 



Large areas to the East are covered with a gravel-like form of 



laterite, occasionally consolidated so as to resem- 



Laterite gravel. 



ble the massive variety. Whether this be pre- 

 cisely the same deposit, or whether it is merely the denuded and frag- 

 mentary detritus of the typical and massive forms of the rock, seems 

 doubtful. There is much in favor of the former view. The gradual 

 thinning which is observed, from the higher ground to the West, to the 

 low plains of alluvium to the East, and the absence of any clear 

 distinction between the two, or of any marked line where the massive 

 form ceases, and the gravelly variety commences, in passing from East 

 to West, seem to point to a common origin for both forms. The rise 

 of level from East to West, already noticed as occurring in Orissa,* 

 appears to be general along the East Coast, and further North, and 

 perhaps an increase of it in the Rajmahal Hills, may explain the masses 

 of laterite which cap their Western ridges. There can now be little 

 doubt, but that the typical " detrital" form of the rock is a marine 

 deposit, and that its peculiar mineral character is due to subse- 

 quent sub-aerial action, the iron having been originally deposited in 

 the rock, and derived from the highly ferruginous metamorphic 

 formations. 



* Mem. Geol. Survey of India, Vol. I., page 274. 



