204 



Geological Society : 



fJuLT 



apparently the base of the country, and the trap penetrates all the 

 formations, including the granite and the freshwater beds. In addiiion 

 to these regular deposits are considerable accumulations of traveiiine 

 and kunkur, which are scatlereci over the whole surface of the coiiniry. 



Grafiite. —Thh rock is frequently displayed in all the rivers- of 

 southern India, and is occasionally visible as the substratum <;f the 

 other formations. In the table-laud of the Mysore it anains an eleva- 

 tion of 3000 feet above the sea. In tiie Deccan, between the Kistjiah 

 and the Godavery, it is traversed by greenstone liykes, soniefiuies por- 

 phyritic, and ranging, for the greater part, from 8. by E. to N. by W., 

 a direction not very different from that of several of the basaliic moun- 

 tains in the northern part of the region ; but on approaching the Goda- 

 very, from the south, the granite is penetrated by dykes, w liicli strike 

 N. and S. Beyond Nagpoor the granite has burst ihrousVi tite red 

 sandstone, which is converted into quartz rock ; and, still further north, 

 granite veins intersect the argillaceous limestone, which has lost its 

 stratified structure. Granite veins also penetrate the neighbouring 

 hills of gneiss and mica slate. 



Gneiss, Mica and Hornblende Slates. —The^e formations appear to be 

 of limited extent. Hornblende slate was noticed by the author only in 

 the neighbourhood of Deemdoortee, twenty miles E. of Neerniul,v\ here 

 it contains the magnetic iron ore used in the manufacture of D.imask 

 steel. Gneiss and mica slate are mentioned only at the locality aUiuled 

 to above, a few miles N. of Nagpoor. 



Trap. — Mr. Malcolmson distinguishes the trap of the dykes from 

 that which constitutes the great basaltic ranges, by the absence of 

 olivine in the former, though it is common in the latter. The great 

 masses of basalt are also distinguished by being amygdaloidal and 

 more crystalline. 



When en masse the trap overlies the granite, as well as the stratified 

 deposits. In the form of veins it traverses the granite, limestone, and 

 sandstone, and the freshwater strata are often imbedded or entangled 

 in it. 



In sinking a well near Hutnoor (lat. IQo 38' N., long. JSo 30' E.), 

 seams of pure white, pulverulent limestone were found beneath layers 

 of basalt, and calcareous depositions appear to accompany the forma- 

 tion almost universally. With respect to the minerals contained in the 

 amygdaloid^, Mr. Malcolmson is of opinion, that they have not been 



