1844.] from Masulipatam to Goa. 907 



direction. The felspar of the granite and gneiss near the line of 

 contact, is deprived of its lustre and translucency : and becomes 

 opaque and white like porcelain : the mica either almost disappears, or 

 shrinks and becomes hard, compact, and of a ferruginous aspect; 

 while the rock en masse acquires a tendency to split into rhomboids. 

 Near the line of contact with the overlying trap a reddish felspathic 

 zone is observed similar to that described as occurring on the trap and 

 granite boundaries at Gurdinny in the S. Mahratta country, S. of 

 Bejapore, which passes into pegmatite soil. The soil from Hydrabad 

 and Golconda to Puttuncherroo is generally the light reddish sandy 

 detritus washed down from the granite heights in the vicinity, occa- 

 sionally mingled with nodules of a ferruginous clay resembling the debris 

 of laterite. A little to the N. and W. of Puttuncherroo, the granitic 

 soil thins out and disappears, leaving exposed the sheet of Regur that 

 underlies it, and which occurs first at intervals, but afterwards as an 

 almost continuous sheet from Moonopilly to Beder. 



Between Puttuncherroo and Moonopilly the strips of granite 

 alluvium with which it is alternated appear to have resulted from 

 the decay of salbandes and bosses of granite, which formerly outcrop- 

 ped from the bed of the Regur, but have since crumbled down by a 

 process of weathering, which I have described elsewhere ; and being 

 washed by the rains, have covered the surrounding soil with a sandy 

 detritus thus : — {See plate, Diagram No. I.) 



A. undecomposed granite. 



B. B. B. decomposed granite forming an alluvial surface soil. 



C. C. Regur. 



Near Sedashipett, a stratum of kunkur intervenes between the Regur 

 and the granite. The surface of the Regur, where it overlies the trap 

 from Moonopilly to Beder, is often intermixed with the detritus of 

 the outcropping trap and laterite rocks associated. The soil resulting 

 from the disintegration of the former is easily distinguishable from 

 the Regur by its much lighter and reddish tinge, arising from the per- 

 oxidation of the protoxide of iron it contains. The detritus of the 

 darkest portions of the trap, even before peroxidation takes place, have 

 a greyish or greenish-brown hue, totally dissimilar to the Regur. 



Boundary of the great overlying trap formation of the Deccan. — A 

 little to the W. of Moonapilly, rounded and angular fragments of the 



