46 POOTE : SOUTH MAHIiATTA COtJWTEY, 



Remarkably porphyritic varieties of syenite gneiss were observed 

 at Bandora on the left bank of the Krishna river, ten miles south-west 

 of Sorapur, and at Hosur, a little south of Jalihal. In the former case 

 the mass of the rock was red, in the latter dark-greenish grey. 



Many of the hills formed of granitoid gneiss are characterised by 



showing generally on their summits, but some- 

 Color of weathered 

 rocks influenced by times also on their flanks, areas in which the 



licli6iis 



assemblage of weathered blocks and tors is of much 

 darker blackish-brown to almost black color than the general surface. 

 Very frequently, if not generally, these dark, highly "blocky" areas 

 show much more rugged surfaces tha^ do the adjoining parts, though 

 made up of blocks of the same size and character. In many cases this 

 darker colored assemblage of blocks appears to form a capping to the 

 hills formed as it were of a younger intrusive rock trappean in character, 

 that had been poured out over the granitoid gneiss, and certainly present 

 that appearance when seen from a distance. 



There are, however, no lines of demarcation between the two rocks 

 when closely examined, and the darker color seems to be external only, 

 for when chipped with the hammer they are found to consist of the same, 

 or an almost identical variety of very compact grey quartzo-fels- 

 pathic granite gneiss, as in the adjoining lighter-colored blocks. Mr. 

 King, who examined the hills south of Raichur, where this curious 

 structure is largely developed, especially in the hills crowned by the ruins 

 of the old Malliabad Drug, was inclined to think the dark-colored assem- 

 blages of blocks might be the fragmentary remnants of overlying beds, 

 differing but little from the underlying ones, excepting in that they 

 weathered of a dark instead of a light color. Various hills in the 

 northern part of Bellary districts and in the Raichur Doab, which exhibit 

 precisely the same structure, were very carefully examined by myself with 

 no satisfactory result at the time, but I have since then come to a 

 different conclusion. I could detect no connection between the different 

 external colors and the bedding of the rocks ; the dark or light color 



( 46 ) 



