1845.] across the Peninsula of Southern India. 507 



nearly tubular masses, which give an appearance of a wall of Cyclopean 

 masonry, running in a line with the crest as far as the eye can reach. 

 The lower beds will be generally found schistose, and of smoother out- 

 line. 



Range to the South of the Bungalow. The eastern extremity of the 

 range to the south of the road has a remarkably rugged appearance, and 

 large masses of rock lie precipitated on its base and sides. On ascend- 

 ing to ascertain the cause of disturbance, I found the hill to have been 

 penetrated by the ramification of a large basaltic dyke. The rock com- 

 posing the dyke passes from a porphyritic to a compact structure. Pale 

 green felspar crystals are imbedded in a crystalline paste of hornblende. 

 Circular and oval cavities, filled with a faint reddish mineral resembling 

 cornelian, and a white mineral resembling prehnite, are found in the 

 greenstone. In the compact varieties augite replaces the hornblende. 

 Near the summit of the hill the basalt appears in four and five sided 

 prisms, about a foot in length, the lower part of the joints convex, fitting 

 into the concave surface of the supporting prisms. A thin incrustation 

 of carbonate of lime occurs between the prisms. The sandstone is 

 highly quartzose, and ferruginous, and acquires a cellular slaggy struc- 

 ture resembling some varieties of laterite. 



In wandering among the chain of hills to the S. of the Bungalow, I 

 picked up some slabs of laminar sandstone, from the surface of which 

 project oval and circular concentric concretions, from the size of a shilling 

 to that of a half-crown in circumference. The outer circle is nearly 

 white, the second darker, enclosing a hard solid nucleus. These con- 

 cretions are harder than the imbedding sandstone, from which they 

 are with difficulty separated, and by weathering less rapidly, project 

 in relief on the surfaces of air-exposed slabs : they penetrated from 

 half an inch to an inch into the substance of the rock. When broken, 

 they do not differ in appearance from the sandstone, except in being a 

 little whiter, and of a finer sand. Some of the more finely laminated 

 slates present on their planes vivid dendroidal delineations. 



Range to the North of the Bungalow. The sandstone hills to the North 

 of the Bungalow support the table-land of Ganjicotta. Ramifications of 

 a greenstone dyke are seen to run along their base, attended by a profu- 

 sion of kunker deposit. 



