318 



Notes illustrative of the Geology of Southern India, [April 



ancp, the atmo5>plieric action had probably reaehed a farther depth of 

 8 or 10 feet, making in a]l from 30 to 35 feet of solid rock penetrated 

 by this destroying power. 



It may be mentioned as an interesting fact, that the contents of the 

 excavations in this vicinity were frequently auriferous, and small 

 quantities of gold were obtained by washing. This is by no means 

 an unfreqiient occurrence in the Mysore country. In blasting sienite 

 at Clnnapatnm, a village about 40 miles from Bangalore on the road 

 to Seringapatam, I occasionally observed considerable quantities of 

 gold disseminated in small particles over the fractured surfaces ; and, 

 at one time, in the vicinily of Wynaad, this metal was obtained 

 from a rich yellow earth, in quantity sufficient to employ a number of 

 labourers, and to yield some return. 



Travelling eastward frorn Bangalore towards Oossoor, the country pre- 

 sents but little either of natural beauty or scientific interest. The 

 beds of the nullahs occasionally exhibit a variety of laterite, whose 

 formation seems to have been materially due to the transporting 

 agency of water. The prevailing rock being the sienitic granite, its 

 decomposition has supplied a large quantity of quartzy pebbles, which 

 are strewed over the fields in every direction. A rush of water after 

 heavy rains transports these to the adjoining nullahs, whose clayey 

 bottoms form a matrix in which they become imbedded, and during 

 the dry season the whole hardens into a compact mass, exhibiting the 

 characteristics of one of the varieties of the laterite. Detached and 

 water-worn fragments of the other varieties were occasionally met with, 

 but no extensive deposits were observed in situ. 



The hills in the vicinity of Oossoor were found to be composed of the 

 universal sienite, exhibiting occasionally with the addition of mica the 

 striated appearance of gneiss. Large veins of pure white quartz and dykes 

 of greenstone traversed the main rock in different directions, without 

 however having caused any alteration at the planes of junction. In many 

 places the sienite had completely decomposed the hornblende into a 

 dark red impalpable earth, and the felspar into a similar white one ; the 

 quartz was in ferruginous pieces, undecomposed, with highly vitreous 

 lustre and splintery fracture. 



Passing from Mysore into the Barramahal district, the primary rocks 

 still prevail. The features of the adjoining country are now, however*, 

 altered, and the comparatively flat and uninteresting plain is exchanged 

 for mountain scenery at once bold and beautiful. Lofty and precipitous 

 hills rising abruptly from the plain, sometimes clothed with rich ver- 

 dure and covered with trees and shrubs to their summits, at other times 

 presenting scarcely one solitary green spot to relieve their desolate and 



