18 BLANFORD: geology of NAGPfJU. 



deposition, as frequently happens where a coarse-textured bed rests upon 

 a fine one, but there is no good reason for believing that any break in the 

 sequence takes place, far less for assigning the rocks above this line to 

 the Mahadevas and those below it to the Damiidas. 



In a quarry nearly a mile farther to the west than the spot where 

 the above section was measured, the coarse grit, No. 8, appears to rest 

 directly on the Ghssopteris bed 11, 9 and 10 being wanting or repre- 

 sented by a layer of argillaceous sandstone a few inches thick. The 

 ferruginous bands in 8 are here strongly developed, and above it there 

 is thick felspathic sandstone. To the east, the outcrop runs along the 

 right bank of the Kanhan river for some distance, and one of the bands 

 of argillaceous sandstone, apparently No. 10, is well exposed. 



The above section is, on the whole, the best met with in the 

 neighbourhood of Nagpur; the rocks opposite Kamthi, though well 

 exposed, being, on the whole, more concealed by alluvial clay. The 

 details given afford a fair conception of the typical kinds of rock in the 

 Kamthi group with one exception, the semivitreous grit quarried for 

 millstones at Bokhara.* 



At SilewMa, as elsewhere, there is a remarkable absence of carbon. 



All the plant remains are mere impressions, the 

 Absence of carbon. n , , i • 



substance ot the leaves being replaced apparently 



by red ochre. It is difficult to say how far this replacement of carbon 



by iron peroxide may have taken place. The yeUow and red compact 



shales may be an altered form of the compact blue and carbonaceous 



shales elsewhere associated with the Damiida rocks, which contain the 



same plants as those of Silewada. This subject, however, will be discussed 



in the sequel. 



* The hardness and peculiar semi-vitreous character of this rock might be ascribed to 

 the neighbourhood of the overlying trap (not to hardening by heat, an effect which rarely 

 extends more than a few inches, but to infiltration of silica) ; but a similar semi-vitreous 

 rock is found elsewhere in the Kamthi beds far from the trap boundary. 



{ 312 ) 



