NEKBUDDA DISTRICT. 167 



the manner of their occurrence. Most remarks bearing on this subject will, 

 however, be reserved for the part of this paper of which the Trap rocks 

 will form the subject. Meanwhile it may be noticed that one of the most 

 remarkable features connected with these dykes is the slightness of the 

 mechanical effect produced by them on the beds of the sedimentary 

 rocks. 



Fig. 6. Sketch Section illustrating relations of Trap and associated beds. 

 a, a, Are flags and sandstones and shales, b, Trap. 



The beds, on which the trap rests, are not seen at the surface, but 

 those restinc on it are well exposed, and these, at the junction of the 

 two rocks, are baked to a porcelain and hardened to a distance of 3 

 inches from the surface of the igneous rock, which itself is earthy and 

 compact at and near the junction, and highly crystalline away from it 

 Were it not disproved by this evidence from the lithological condition of 

 both the sedimentary and igneous rocks, it would be difficult to resist 

 the conviction that the beds which rest on the trap had been deposited 

 subsequently to its consolidation; so slightly does itsi ntrusion seem to 

 have affected the mechanical condition of the beds. 



As in the valley of the Tawa, we here find the rocks of the Talcheer 



and Lower Damuda groups presenting a flat or 

 In the upper Deinwa 

 Valley. gently undulating surface, from which the massive 



vertical scarps of the Mahadeva sandstone rise. 



The sketch given on the next page fig. 7, illustrates this. The low 

 ground here being occupied by the beds of the sub-divisions d, and e 

 of which the above measured section gives an example. 



With regard to the thickness of these beds, as seen here, what has been 

 already said will suffice to point out how difficult it has been found to 



