1012 
MANGANESE DEPOSITS OF INDIA : DESCRIPTIVE. [ PaRT IV : 
and remains of original structures of phyllitic rocks these lithomarges 
show, this does not seom very probable. Hence it seems necessary to 
suppose that the aluminous and siliceous material of the replaced rocks 
was usually completely carried away in solution. 
At Ramandrug Main Bed, as will be seen from Fig. 76, the manganese- 
ore extends 50 feet, or a little more, inward 
poStTSUd. from the original outcrop along the bedding 
planes of the replaced rock. The depth at 
Ramandrug No. 4 is about the same ; whilst the indications at Sannasil 
Haruvu are that the bottom of the manganese-ore will be reached at a 
similar depth. It is perhaps hardly fair to judge from these three 
deposits situated in one part of the State as to the depth to which the 
deposits in other parts will be found to continue. In the Kamataru 
area, where no work has been done on the ore except to break up a few 
surface boulders, the ores seen in the outcrops display all the mineralo- 
gical and structural peculiarities of the Ramandrug ores. Hence we 
can fairly suppose that, like those of Ramandrug, the Kamataru ores have 
been formed by superficial replacement, although one would never have 
Supposed it had the Ramandrug deposits not been opened up. At 
Kamataru, however, it is probable that the ores sometimes continue to 
a greater depth than at Ramandrug. In the first place, the tendency 
with deposits formed by superficial replacement is for the ores to be 
best in quality at the surface, and to become poorer, owing to the 
presence of a larger residue of the original rock material, the greater is 
the depth from the surface. In discussing the minerals of the Sandur 
deposits I have mentioned that the ores at Kamataru are generally of 
higher grade than those at Ramandrug. The meaning of this may be 
that the Ramandrug deposits have been eroded to a greater dehth from 
the surface than those of Kamataru, or that the replacement at 
Kamataru has been more complete. In either case we should expect 
the Kamataru deposits to extend to a greater depth from the surface 
than those of Ramandrug. That this is probably the case in at least 
one or two cases is indicated by the outcrops. Thus at Durgamma 
Kolla there is a very fine cliff- like outcrop a Uttle below the edge of the 
plateau (see Plate 46). It is 48 feet high at its highest point, and one 
may conclude from this that the manganese-ore may continue in depth 
for a greater distance than 50 feet from the top of the outcrop along 
