NERBUDDA DISTRICT. 197 



the east they rest on those rocks ; so that their thickness being incon- 

 siderable, and their present boundary being determined by denudation, 

 they are found at the base of, and following all the contours of the trap 

 hills. They thus appear on the map as a narrow strip between the trap 

 and the Damuda rocks. 



Liihologicalty considered they may be described as follows, the sub- 



l. . , , . , , . x . divisions being; taken in ascending; order as far as 

 Lithological description a a 



oftheLametas. possible, but being at the same time strictly litho- 



logical, and not stratigraphical. 



(a) Greenish sandstone, mostly loosely aggregated but sometimes 

 hard and even cherty. 



(b) The characteristic bed of the series is an impure earthy limestone, 

 or indurated marl of a pale drab, or blueish grey color, often 

 traversed by many vein like cavities which give a tufaceous 

 aspect to the rock, these are often filled with bands or segrega- 

 tions of chalcedonic quartz, or of carbonate of lime. Most fre- 

 quently the cavities are incompletely filled in a way suggestive of 

 infiltration. 



(c) Pale purple and pale green muds, sometimes with sufficiently dis- 

 tinct lamination to deserve the name of shale. These are some- 

 times arenaceous and form earthy sandstone; sometimes calcareous, 

 being then marl. 



(d) Sandstone with the tufaceous aspect of sub-division b, it contains 

 bands and segregations of flint, and sometimes even of carbonate 

 of lime : it is sometimes formed of grains of glassy quartz cement- 

 ed by a white powdery matrix, friable generally, though in places 

 intensely hard. 



No single section presents all these varieties, but wherever the base of 



Remarks on these sub- tbe series is seen > sub-division a is found to under- 

 lie all others. It is sometimes brown jred in color, 

 instead of green, as near Jubbulpur, where some difficulty is found in 



