the Eastern Portion of the Basaltic District of India. 543 



able, and its inferior beds are not unfrequently schistose, so as to be with difficulty distinguished 

 from the subjacent rock, with which it has in one or two places been observed to alternate. Where 

 the sandstone approaches the great granitic tracts to the south and west, it passes into a compact 

 quartzose rock, as is seen on both sides of the Tripatty Valley. This passage is also observed in 

 other places, as near the Cuddapah diamond mines, where the plentiful occurrence of basaltic peb- 

 bles shows the neighbourhood of the trap. Besides the diamond conglomerate, consisting of a 

 great variety of minerals, seams of rock crystal occur, and a fine white quartz containing argenti- 

 ferous galena, which in former times furnished the country with lead. Specular and micaceous 

 magnetic iron ores, but'containing much peroxide, and common iron pyrites, occur with the galena. 

 As far as I have observed, the sandstone always rests conformably on the schists, although from 

 its jointed structure it occasionally, when elevated, appears to meet the subjacent rock at a more 

 or less obtuse angle. 



The schists on which the sandstone rests, vary very remarkably in colour, being in different 

 places blue, red, green, or pure white, in which they seem to bear some relation to the incumbent 

 sandstone. They are also occasionally flinty or jaspideous. Sometimes they are wanting, the 

 sandstone resting directly on the limestone, of which the schists are evidently merely the upper 

 beds, and into which they pass insensibly, although it seldom happens that considerable efferves- 

 cence does not occur on examination by tests. It is in many places impossible to say to which 

 portion of the series any particular specimen belongs. 



Voysey has classed the schists with the sandstone under the name of "(the clay slate formation ;)" 

 I have, however, preferred to designate the deposit " argillaceous limestone," a term used by him 

 in one of his sections as applicable to the limestone, and which well expresses not only the general 

 character of the rock, but that also of the upper schistose beds. 



The limestone is a compact rock, but the strata are usually thin, and are often intersected by 

 vertical partings, a circumstance which frequently limits its use in ornamental architecture. Its 

 most common colour is a light blue, passing into black ; but it occasionally occurs of a nearly pure 

 white, and affords an admirable material for basso-relievos. On this stone the finest sculptures of the 

 ruined city of Amrawuty are executed, and for delicacy of workmanship they have perhaps never 

 been surpassed. Were it not for the occurrence of small crystals of quartz, the same quarries 

 would furnish an excellent lithographic stone. Near Cuddapah the dark variety is the common 

 building stone, and many fine columns, caryatides, and cisterns are composed of it. The stone is 

 applied to the same objects in the southern Mahratta country, and along the course of the Go- 

 davery towards Nagpoor. 



To the south and east of Cuddapah,, a narrow valley^ nearly J 50 miles in 

 lengthy extends through the limestone, the strata of which are in some places 

 nearly vertical^ but form rounded hills. In others they are capped by sand- 

 stone, which exhibits mural precipices of much grandeur, and almost or en- 

 tirely inaccessible. The strata, for the most part, dip to the N.W., resting 

 on the granite of the Carnatic. This rock is penetrated by many dikes of 

 greenstone, which have evidently been instrumental in elevating the stratified 

 rocks to their present singular positions. Little has yet been ascertained re- 

 garding the thickness of these strata, which differ much even in the same 

 range of hills. The only minerals they have been ascertained to yield, are 

 varieties of quartz and iron pyrites, the latter of which is so abundant in a few 



