543 J. G. Malcolmson^ Esq., on the Fossils of 



abounds with springs, and is in some places so cavernous as to afford passage to 

 subterranean streams. Basalt protrudes in a few places near Bangnapilly. 

 On ascending the hill, the limestone becomes more schistose, and is of a paler 

 colour, gradually approaching in its structure and composition to clay slate, 

 but it is far more friable. On the schist a more or less compact sandstone rests, 

 varying very much in colour, composition, and appearance in different places. 

 Above Bangnapilly it contains the diamond breccia described by Voysey. As 

 far as the shafts which I had an opportunity of observing, enabled me to judge, 

 the breccia is not an interstratified rock, but an intermixture of the common 

 sandstone, in different parts of the same stratum, with larger fragments of 

 older rocks, generally rounded but sometimes angular. It is not, however, 

 the object of this paper to describe the mines and the interesting district in 

 which they occur further than is necessary to exhibit the type of the forma- 

 tion, by the study of which I was enabled to understand more clearly, the less 

 distinct appearances exhibited by the same rocks, where they have been inva- 

 ded or buried by the great basaltic eruptions of Central India. On the oppo- 

 site or west side of the valley, the hill is composed of the same argillo-calca- 

 reous formation; but, according to Colonel Cullen, " instead of a sandstone cap, 

 it is crested in its whole length with a sharp black ridge of trap rock, formed 

 of loose blocks piled upon each other, the apparent base of which observed a 

 pretty uniform level, nor is the ridge of much depth. Its extreme narrow- 

 ness, deep black colour, and the total absence of all traces of vegetation, 

 formed a singular contrast to the rest of the hills, which were covered with 

 long dry grass and scattered bushes*." At a small pass some miles further to 

 the west, the road in ascending, passes over first the dark limestone and a nar- 

 row belt of schist, then trap, which is again succeeded by limestone, and the 

 latter by schist, nearly to the summit, " which is capped with a rock of a beau- 

 tiful flesh colour, with specks and shades of a beautiful green, as if connected 

 with its vicinity to the trap, and of so close and fine a texture as to appear 

 homogeneous even with a lens." " The descent of the pass on the opposite side 

 consists of a clay slate nearly to the foot, where the limestone reappears, and 

 these two rocks continued to alternate with each other to the foot of the second 

 Ghat, which, like all the former, was composed of clay slate capped with 

 quartzose sandstone f." 



The sandstone exhibits many varieties of grain, colour, and hardness : in some places it is white 

 or red, and can be cut into pillars and slabs of great size and beauty ; in others it is soft and fri- 



* ColonelCullen, in Transactions ofthe Literary Society of Madras, January 1837, p. 50. t Ibid. 



