MALLET, VINDHYAN SERIES. 39 



observed together on a very small slab of stone. Layers and bands of 

 sandstone and also limestone are very commonly intercalated with these 

 strata. Indeed the boundary between the sub-divisions of different 

 mineral characters of the lower Vindhyans is, especially in the west, 

 seldom clearly defined. The arenaceous portions mix with, and faU into, 

 the argillaceous, and each in its turn into the calcareous, the transition 

 being often by slow gradations. In other cases, however, the division is 

 trenchant enough, and the shale, the sandstone, and the limestone are all 

 typically contrasted in mineral and physical characters at their res- 

 pective ejunctions. 



No. 7 is the limestone to whose hardness, as compared with the 



shales above and below, combined with the distm^b- 

 7. Limestone, 



anees which have affected them all, are due the 



nearly parallel hill ranges which intervene between the escarpment and 

 the Sone, south-east of Bijigurh. At Jaradag it is a most peculiar rock ; a 

 confused mixture of compact fawn-colored limestone, calcareous spar, and 

 a small proportion of quartz, as chalcedony, and crystalHzed. Some lay- 

 ers contain bands of black chert, the cavities in which are lined with rock 

 crystal. Further west the rock is usually fawn-colored, or sometimes 

 light blue, and looks homogeneous in texture on a new fracture, but that 

 it is not so in reality is shown by the rough, honeycombed aspect of its 

 weathered blocks. The bedding averages 2 to 4 feet, and the total thick- 

 ness at Jaradag is about 40, which gradually increases to 150 feet or so 

 near the mouth of the Ghagm-. Beyond this point the limestone we are 

 speaking of is obscured by alluvium for a long distance. It is seen again 

 at Hurma, 10 miles east of Bm-dhee, about 40 feet being exposed, but at 

 Burdhee itself it seems to be absent from the section. There can be little 

 doubt that the band which runs along the southern face of the Keinjua 

 hiUs, south of Badanpur, is to be referred to this position in the section, 

 but between these distant points observations are wanting. 



( 39 ) 



