100 GEOLOGY OF THE SON VALLEY, ETC. 



amorphous variety of the coarse, porphyritic pseudo-granite ; great 

 bare masses presenting acres of convex surface without a crack. 

 Closely packed between these domes and encircling their bases 

 is a pseudo-crystalline rock — a rock which in a hand-specimen 

 I would have set down as a granitoid trap, or trappoid granite ; 

 compact felspar being largely present. I got one observation 

 showing more fully the relation of this rock to the thorough- 

 looking granite. On the path leading from the village of Kala- 

 pahar on the North, through the hills to Kota on the South, the 

 first low dome on the right hand presents an exceptional feature : 

 over a large portion of the boss, and reaching quite to the top, there 

 is the remains of an outer shell, of a most regular thickness, some 

 six or seven feet. This upper crust is of the trappoid variety, and it 

 is in sharp contact with the coarsely crystalline central mass, just 

 like two strata ; on the East side the edge of the outer mass is 

 straight, giving the appearance as if half the dome were entirely com- 

 posed of it ; but on the West side the edge is not continuous with 

 that on the East, and is, moreover, broken and indented, leaving 

 no doubt that the coarse rock underlies throughout." 



After describing some more similar occurrences, Mr. Medlicott 

 comes to the following conclusion : " These sections leave little 

 doubt as to the origin of these peculiar Sone strata, though much 

 remains to be observed and considered as to the conditions of their 

 formation. I can hardly seriously entertain the view of their being 

 trappean or volcanic/' 



The same opinion is given in the Memoirs (Vol. VII, page 36). 

 u It rests directly on granitoid gneiss, and its examination strongly 

 leads one to believe in its being a sedimentary rock made up of the 

 debris of the latter/' The results of subsequent examination have 

 now caused these conclusions to be modified to a certain extent. 



Both the gneiss (specimen -f \) and the overlying "trappoid" 



(specimens y^-g and T ^ ¥ ) are represented in the collection. The 



gneiss \\ is described in the register as u granitic gneiss on which 



.„ . , the trappoid rock rests with perfectly sharp 



Gneiss of Kalapahar. . , . . 



junction,' In the h#nd-specimen it appears as 

 ( 100 ) 



